[PATCH 00/25] mm: Preemptibility -v7

[PATCH 00/25] mm: Preemptibility -v7

[Peter Zijlstra]

This patch-set makes part of the mm a lot more preemptible. It converts
i_mmap_lock and anon_vma->lock to mutexes and makes mmu_gather fully
preemptible.

The main motivation was making mm_take_all_locks() preemptible, since it
appears people are nesting hundreds of spinlocks there.

The side-effects are that can finally make mmu_gather preemptible,
something which lots of people have wanted to do for a long time.

It also gets us anon_vma refcounting, which seems to result in a nice
cleanup of the anon_vma lifetime rules wrt KSM and compaction.

This patch-set is build and boot-tested on x86_64 (a previous version was
also tested on Dave's Niagra2 machines, and I suppose s390 was too when
Martin provided the conversion patch for his arch).

There are no known architectures left unconverted.

Yanmin ran the -v3 posting through the comprehensive Intel test farm
and didn't find any regressions.

( Not included in this posting are the 4 Sparc64 patches that implement
  gup_fast, those can be applied separately after this series gets
  anywhere. )

The full series (including the Sparc64 gup_fast bits) also available in -git
form from (against something post .38-rc2):

  git://git.kernel.org/pub/scm/linux/kernel/git/peterz/linux-2.6-mmu_preempt.git


Changes since -v6:

Suggested by Hugh:
 - reordered the patches
 - changed to GFP_NOWAIT | __GFP_NOWARN to allocate mmu_gather pages
 - s/lock/mutex/ for the spinlock to mutex conversion
 - removed all DEFINE_PER_CPU(struct mmu_gather, mmu_gather) remnants
 - split the i_mmap_lock and anon_vma->lock conversion
 - removed some KSM wrappers
 - avoid tlb_flush_mmu() while holding pte_lock

Other:
 - remove the i_mmap_lock lockbreak in truncate (XXX)
 - arch/tile __pte_free_tlb() change

TODO:
 - decide if we want to actually remove the i_mmap_lock lockbreak
 - figure out if LOCK vs MB works or add a smp_mb() to patch #23
 - figure out what to do with sparc's tlb_batch lack of ->fullmm


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[PATCH 01/25] tile: Fix __pte_free_tlb

[Peter Zijlstra]

[-- Attachment #1: tile-fix-pte_free_tlb.patch --]
[-- Type: text/plain, Size: 1552 bytes --]

Tile's __pte_free_tlb() implementation makes assumptions about the
generic mmu_gather implementation, cure this ;-)

[ Chris, from a quick look L2_USER_PGTABLE_PAGES is something like:
  1 << (24 - 16 + 3), which looks awefully large for an on-stack
  array. ]

Cc: Chris Metcalf <cmetcalf@tilera.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/tile/mm/pgtable.c |   15 ++-------------
 1 file changed, 2 insertions(+), 13 deletions(-)

Index: linux-2.6/arch/tile/mm/pgtable.c
===================================================================
--- linux-2.6.orig/arch/tile/mm/pgtable.c
+++ linux-2.6/arch/tile/mm/pgtable.c
@@ -252,19 +252,8 @@ void __pte_free_tlb(struct mmu_gather *t
 	int i;
 
 	pgtable_page_dtor(pte);
-	tlb->need_flush = 1;
-	if (tlb_fast_mode(tlb)) {
-		struct page *pte_pages[L2_USER_PGTABLE_PAGES];
-		for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
-			pte_pages[i] = pte + i;
-		free_pages_and_swap_cache(pte_pages, L2_USER_PGTABLE_PAGES);
-		return;
-	}
-	for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i) {
-		tlb->pages[tlb->nr++] = pte + i;
-		if (tlb->nr >= FREE_PTE_NR)
-			tlb_flush_mmu(tlb, 0, 0);
-	}
+	for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
+		tlb_remove_page(tlb, pte + i);
 }
 
 #ifndef __tilegx__


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Re: [PATCH 01/25] tile: Fix __pte_free_tlb

[Chris Metcalf]

On 1/25/2011 12:31 PM, Peter Zijlstra wrote:
> Tile's __pte_free_tlb() implementation makes assumptions about the
> generic mmu_gather implementation, cure this ;-)

I assume you will take this patch into your tree?  If so:

Acked-by: Chris Metcalf <cmetcalf@tilera.com>

> [ Chris, from a quick look L2_USER_PGTABLE_PAGES is something like:
>   1 << (24 - 16 + 3), which looks awefully large for an on-stack
>   array. ]

Yes, the pte_pages[] array in this routine is 2KB currently.  Currently we
ship with 64KB pagesize, so the kernel stack has plenty of room.  I do like
that your patch removes this buffer, however, since we're currently looking
into (re-)supporting 4KB pages, which would totally blow the kernel stack
in this routine.

> Cc: Chris Metcalf <cmetcalf@tilera.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> ---
>  arch/tile/mm/pgtable.c |   15 ++-------------
>  1 file changed, 2 insertions(+), 13 deletions(-)
>
> Index: linux-2.6/arch/tile/mm/pgtable.c
> ===================================================================
> --- linux-2.6.orig/arch/tile/mm/pgtable.c
> +++ linux-2.6/arch/tile/mm/pgtable.c
> @@ -252,19 +252,8 @@ void __pte_free_tlb(struct mmu_gather *t
>  	int i;
>  
>  	pgtable_page_dtor(pte);
> -	tlb->need_flush = 1;
> -	if (tlb_fast_mode(tlb)) {
> -		struct page *pte_pages[L2_USER_PGTABLE_PAGES];
> -		for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
> -			pte_pages[i] = pte + i;
> -		free_pages_and_swap_cache(pte_pages, L2_USER_PGTABLE_PAGES);
> -		return;
> -	}
> -	for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i) {
> -		tlb->pages[tlb->nr++] = pte + i;
> -		if (tlb->nr >= FREE_PTE_NR)
> -			tlb_flush_mmu(tlb, 0, 0);
> -	}
> +	for (i = 0; i < L2_USER_PGTABLE_PAGES; ++i)
> +		tlb_remove_page(tlb, pte + i);
>  }
>  
>  #ifndef __tilegx__
>
>

-- 
Chris Metcalf, Tilera Corp.
http://www.tilera.com

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Re: [PATCH 01/25] tile: Fix __pte_free_tlb

[Peter Zijlstra]

On Fri, 2011-02-04 at 15:39 -0500, Chris Metcalf wrote:
> On 1/25/2011 12:31 PM, Peter Zijlstra wrote:
> > Tile's __pte_free_tlb() implementation makes assumptions about the
> > generic mmu_gather implementation, cure this ;-)
> 
> I assume you will take this patch into your tree?  If so:
> 
> Acked-by: Chris Metcalf <cmetcalf@tilera.com>

Feel free to take it yourself, this series might take a while to land..

> > [ Chris, from a quick look L2_USER_PGTABLE_PAGES is something like:
> >   1 << (24 - 16 + 3), which looks awefully large for an on-stack
> >   array. ]
> 
> Yes, the pte_pages[] array in this routine is 2KB currently.  Currently we
> ship with 64KB pagesize, so the kernel stack has plenty of room.  I do like
> that your patch removes this buffer, however, since we're currently looking
> into (re-)supporting 4KB pages, which would totally blow the kernel stack
> in this routine.

Ah, ok.

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Re: [PATCH 01/25] tile: Fix __pte_free_tlb

[Chris Metcalf]

On 2/7/2011 8:55 AM, Peter Zijlstra wrote:
> On Fri, 2011-02-04 at 15:39 -0500, Chris Metcalf wrote:
>> On 1/25/2011 12:31 PM, Peter Zijlstra wrote:
>>> Tile's __pte_free_tlb() implementation makes assumptions about the
>>> generic mmu_gather implementation, cure this ;-)
>> I assume you will take this patch into your tree?  If so:
>>
>> Acked-by: Chris Metcalf <cmetcalf@tilera.com>
> Feel free to take it yourself, this series might take a while to land..

Thanks, I took it into my tree (without the comment about the on-stack array).

-- 
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http://www.tilera.com

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[PATCH 02/25] mm: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 10478 bytes --]

Make mmu_gather preemptible by using a small on stack list and use
an option allocation to speed things up.

Preemptible mmu_gather is desired in general and usable once
i_mmap_lock becomes a mutex. Doing it before the mutex conversion
saves us from having to rework the code by moving the mmu_gather
bits inside the pte_lock.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Cc: David Miller <davem@davemloft.net>
Cc: Martin Schwidefsky <schwidefsky@de.ibm.com>
Cc: Russell King <rmk@arm.linux.org.uk>
Cc: Paul Mundt <lethal@linux-sh.org>
Cc: Jeff Dike <jdike@addtoit.com>
Cc: Tony Luck <tony.luck@intel.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 fs/exec.c                 |   10 ++++-----
 include/asm-generic/tlb.h |   51 +++++++++++++++++++++++++++++-----------------
 include/linux/mm.h        |    2 -
 mm/memory.c               |   27 +++++-------------------
 mm/mmap.c                 |   18 ++++++++--------
 5 files changed, 54 insertions(+), 54 deletions(-)

Index: linux-2.6/fs/exec.c
===================================================================
--- linux-2.6.orig/fs/exec.c
+++ linux-2.6/fs/exec.c
@@ -550,7 +550,7 @@ static int shift_arg_pages(struct vm_are
 	unsigned long length = old_end - old_start;
 	unsigned long new_start = old_start - shift;
 	unsigned long new_end = old_end - shift;
-	struct mmu_gather *tlb;
+	struct mmu_gather tlb;
 
 	BUG_ON(new_start > new_end);
 
@@ -576,12 +576,12 @@ static int shift_arg_pages(struct vm_are
 		return -ENOMEM;
 
 	lru_add_drain();
-	tlb = tlb_gather_mmu(mm, 0);
+	tlb_gather_mmu(&tlb, mm, 0);
 	if (new_end > old_start) {
 		/*
 		 * when the old and new regions overlap clear from new_end.
 		 */
-		free_pgd_range(tlb, new_end, old_end, new_end,
+		free_pgd_range(&tlb, new_end, old_end, new_end,
 			vma->vm_next ? vma->vm_next->vm_start : 0);
 	} else {
 		/*
@@ -590,10 +590,10 @@ static int shift_arg_pages(struct vm_are
 		 * have constraints on va-space that make this illegal (IA64) -
 		 * for the others its just a little faster.
 		 */
-		free_pgd_range(tlb, old_start, old_end, new_end,
+		free_pgd_range(&tlb, old_start, old_end, new_end,
 			vma->vm_next ? vma->vm_next->vm_start : 0);
 	}
-	tlb_finish_mmu(tlb, new_end, old_end);
+	tlb_finish_mmu(&tlb, new_end, old_end);
 
 	/*
 	 * Shrink the vma to just the new range.  Always succeeds.
Index: linux-2.6/include/asm-generic/tlb.h
===================================================================
--- linux-2.6.orig/include/asm-generic/tlb.h
+++ linux-2.6/include/asm-generic/tlb.h
@@ -22,14 +22,8 @@
  * and page free order so much..
  */
 #ifdef CONFIG_SMP
-  #ifdef ARCH_FREE_PTR_NR
-    #define FREE_PTR_NR   ARCH_FREE_PTR_NR
-  #else
-    #define FREE_PTE_NR	506
-  #endif
   #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
 #else
-  #define FREE_PTE_NR	1
   #define tlb_fast_mode(tlb) 1
 #endif
 
@@ -39,30 +33,48 @@
 struct mmu_gather {
 	struct mm_struct	*mm;
 	unsigned int		nr;	/* set to ~0U means fast mode */
+	unsigned int		max;	/* nr < max */
 	unsigned int		need_flush;/* Really unmapped some ptes? */
 	unsigned int		fullmm; /* non-zero means full mm flush */
-	struct page *		pages[FREE_PTE_NR];
+#ifdef HAVE_ARCH_MMU_GATHER
+	struct arch_mmu_gather	arch;
+#endif
+	struct page		**pages;
+	struct page		*local[8];
 };
 
-/* Users of the generic TLB shootdown code must declare this storage space. */
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
+static inline void __tlb_alloc_page(struct mmu_gather *tlb)
+{
+	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+
+	if (addr) {
+		tlb->pages = (void *)addr;
+		tlb->max = PAGE_SIZE / sizeof(struct page *);
+	}
+}
 
 /* tlb_gather_mmu
  *	Return a pointer to an initialized struct mmu_gather.
  */
-static inline struct mmu_gather *
-tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
-
 	tlb->mm = mm;
 
-	/* Use fast mode if only one CPU is online */
-	tlb->nr = num_online_cpus() > 1 ? 0U : ~0U;
+	tlb->max = ARRAY_SIZE(tlb->local);
+	tlb->pages = tlb->local;
+
+	if (num_online_cpus() > 1) {
+		tlb->nr = 0;
+		__tlb_alloc_page(tlb);
+	} else /* Use fast mode if only one CPU is online */
+		tlb->nr = ~0U;
 
 	tlb->fullmm = full_mm_flush;
 
-	return tlb;
+#ifdef HAVE_ARCH_MMU_GATHER
+	tlb->arch = ARCH_MMU_GATHER_INIT;
+#endif
 }
 
 static inline void
@@ -75,6 +87,8 @@ tlb_flush_mmu(struct mmu_gather *tlb, un
 	if (!tlb_fast_mode(tlb)) {
 		free_pages_and_swap_cache(tlb->pages, tlb->nr);
 		tlb->nr = 0;
+		if (tlb->pages == tlb->local)
+			__tlb_alloc_page(tlb);
 	}
 }
 
@@ -90,7 +104,8 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	put_cpu_var(mmu_gathers);
+	if (tlb->pages != tlb->local)
+		free_pages((unsigned long)tlb->pages, 0);
 }
 
 /* tlb_remove_page
@@ -106,7 +121,7 @@ static inline void tlb_remove_page(struc
 		return;
 	}
 	tlb->pages[tlb->nr++] = page;
-	if (tlb->nr >= FREE_PTE_NR)
+	if (tlb->nr >= tlb->max)
 		tlb_flush_mmu(tlb, 0, 0);
 }
 
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -887,7 +887,7 @@ int zap_vma_ptes(struct vm_area_struct *
 		unsigned long size);
 unsigned long zap_page_range(struct vm_area_struct *vma, unsigned long address,
 		unsigned long size, struct zap_details *);
-unsigned long unmap_vmas(struct mmu_gather **tlb,
+unsigned long unmap_vmas(struct mmu_gather *tlb,
 		struct vm_area_struct *start_vma, unsigned long start_addr,
 		unsigned long end_addr, unsigned long *nr_accounted,
 		struct zap_details *);
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1121,17 +1121,14 @@ static unsigned long unmap_page_range(st
  * ensure that any thus-far unmapped pages are flushed before unmap_vmas()
  * drops the lock and schedules.
  */
-unsigned long unmap_vmas(struct mmu_gather **tlbp,
+unsigned long unmap_vmas(struct mmu_gather *tlb,
 		struct vm_area_struct *vma, unsigned long start_addr,
 		unsigned long end_addr, unsigned long *nr_accounted,
 		struct zap_details *details)
 {
 	long zap_work = ZAP_BLOCK_SIZE;
-	unsigned long tlb_start = 0;	/* For tlb_finish_mmu */
-	int tlb_start_valid = 0;
 	unsigned long start = start_addr;
 	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
-	int fullmm = (*tlbp)->fullmm;
 	struct mm_struct *mm = vma->vm_mm;
 
 	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
@@ -1152,11 +1149,6 @@ unsigned long unmap_vmas(struct mmu_gath
 			untrack_pfn_vma(vma, 0, 0);
 
 		while (start != end) {
-			if (!tlb_start_valid) {
-				tlb_start = start;
-				tlb_start_valid = 1;
-			}
-
 			if (unlikely(is_vm_hugetlb_page(vma))) {
 				/*
 				 * It is undesirable to test vma->vm_file as it
@@ -1177,7 +1169,7 @@ unsigned long unmap_vmas(struct mmu_gath
 
 				start = end;
 			} else
-				start = unmap_page_range(*tlbp, vma,
+				start = unmap_page_range(tlb, vma,
 						start, end, &zap_work, details);
 
 			if (zap_work > 0) {
@@ -1185,19 +1177,13 @@ unsigned long unmap_vmas(struct mmu_gath
 				break;
 			}
 
-			tlb_finish_mmu(*tlbp, tlb_start, start);
-
 			if (need_resched() ||
 				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
-				if (i_mmap_lock) {
-					*tlbp = NULL;
+				if (i_mmap_lock)
 					goto out;
-				}
 				cond_resched();
 			}
 
-			*tlbp = tlb_gather_mmu(vma->vm_mm, fullmm);
-			tlb_start_valid = 0;
 			zap_work = ZAP_BLOCK_SIZE;
 		}
 	}
@@ -1217,16 +1203,15 @@ unsigned long zap_page_range(struct vm_a
 		unsigned long size, struct zap_details *details)
 {
 	struct mm_struct *mm = vma->vm_mm;
-	struct mmu_gather *tlb;
+	struct mmu_gather tlb;
 	unsigned long end = address + size;
 	unsigned long nr_accounted = 0;
 
 	lru_add_drain();
-	tlb = tlb_gather_mmu(mm, 0);
+	tlb_gather_mmu(&tlb, mm, 0);
 	update_hiwater_rss(mm);
 	end = unmap_vmas(&tlb, vma, address, end, &nr_accounted, details);
-	if (tlb)
-		tlb_finish_mmu(tlb, address, end);
+	tlb_finish_mmu(&tlb, address, end);
 	return end;
 }
 
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c
+++ linux-2.6/mm/mmap.c
@@ -1913,17 +1913,17 @@ static void unmap_region(struct mm_struc
 		unsigned long start, unsigned long end)
 {
 	struct vm_area_struct *next = prev? prev->vm_next: mm->mmap;
-	struct mmu_gather *tlb;
+	struct mmu_gather tlb;
 	unsigned long nr_accounted = 0;
 
 	lru_add_drain();
-	tlb = tlb_gather_mmu(mm, 0);
+	tlb_gather_mmu(&tlb, mm, 0);
 	update_hiwater_rss(mm);
 	unmap_vmas(&tlb, vma, start, end, &nr_accounted, NULL);
 	vm_unacct_memory(nr_accounted);
-	free_pgtables(tlb, vma, prev? prev->vm_end: FIRST_USER_ADDRESS,
-				 next? next->vm_start: 0);
-	tlb_finish_mmu(tlb, start, end);
+	free_pgtables(&tlb, vma, prev ? prev->vm_end : FIRST_USER_ADDRESS,
+				 next ? next->vm_start : 0);
+	tlb_finish_mmu(&tlb, start, end);
 }
 
 /*
@@ -2265,7 +2265,7 @@ EXPORT_SYMBOL(do_brk);
 /* Release all mmaps. */
 void exit_mmap(struct mm_struct *mm)
 {
-	struct mmu_gather *tlb;
+	struct mmu_gather tlb;
 	struct vm_area_struct *vma;
 	unsigned long nr_accounted = 0;
 	unsigned long end;
@@ -2290,14 +2290,14 @@ void exit_mmap(struct mm_struct *mm)
 
 	lru_add_drain();
 	flush_cache_mm(mm);
-	tlb = tlb_gather_mmu(mm, 1);
+	tlb_gather_mmu(&tlb, mm, 1);
 	/* update_hiwater_rss(mm) here? but nobody should be looking */
 	/* Use -1 here to ensure all VMAs in the mm are unmapped */
 	end = unmap_vmas(&tlb, vma, 0, -1, &nr_accounted, NULL);
 	vm_unacct_memory(nr_accounted);
 
-	free_pgtables(tlb, vma, FIRST_USER_ADDRESS, 0);
-	tlb_finish_mmu(tlb, 0, end);
+	free_pgtables(&tlb, vma, FIRST_USER_ADDRESS, 0);
+	tlb_finish_mmu(&tlb, 0, end);
 
 	/*
 	 * Walk the list again, actually closing and freeing it,


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[PATCH 03/25] powerpc: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-powerpc-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 9091 bytes --]

Fix up powerpc to the new mmu_gather stuffs.

PPC has an extra batching queue to RCU free the actual pagetable
allocations, use the ARCH extentions for that for now.

For the ppc64_tlb_batch, which tracks the vaddrs to unhash from the
hardware hash-table, keep using per-cpu arrays but flush on context
switch and use a TLF bit to track the laxy_mmu state.

Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/powerpc/include/asm/pgalloc.h     |    4 ++--
 arch/powerpc/include/asm/thread_info.h |    2 ++
 arch/powerpc/include/asm/tlb.h         |   10 ++++++++++
 arch/powerpc/kernel/process.c          |   23 ++++++++++++++++++++++-
 arch/powerpc/mm/pgtable.c              |   14 ++++----------
 arch/powerpc/mm/tlb_hash32.c           |    2 +-
 arch/powerpc/mm/tlb_hash64.c           |   12 +++++++-----
 arch/powerpc/mm/tlb_nohash.c           |    2 +-
 8 files changed, 49 insertions(+), 20 deletions(-)

Index: linux-2.6/arch/powerpc/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/tlb.h
+++ linux-2.6/arch/powerpc/include/asm/tlb.h
@@ -28,6 +28,16 @@
 #define tlb_start_vma(tlb, vma)	do { } while (0)
 #define tlb_end_vma(tlb, vma)	do { } while (0)
 
+#define HAVE_ARCH_MMU_GATHER 1
+
+struct pte_freelist_batch;
+
+struct arch_mmu_gather {
+	struct pte_freelist_batch *batch;
+};
+
+#define ARCH_MMU_GATHER_INIT (struct arch_mmu_gather){ .batch = NULL, }
+
 extern void tlb_flush(struct mmu_gather *tlb);
 
 /* Get the generic bits... */
Index: linux-2.6/arch/powerpc/kernel/process.c
===================================================================
--- linux-2.6.orig/arch/powerpc/kernel/process.c
+++ linux-2.6/arch/powerpc/kernel/process.c
@@ -393,6 +393,9 @@ struct task_struct *__switch_to(struct t
 	struct thread_struct *new_thread, *old_thread;
 	unsigned long flags;
 	struct task_struct *last;
+#ifdef CONFIG_PPC_BOOK3S_64
+	struct ppc64_tlb_batch *batch;
+#endif
 
 #ifdef CONFIG_SMP
 	/* avoid complexity of lazy save/restore of fpu
@@ -511,7 +514,17 @@ struct task_struct *__switch_to(struct t
 		old_thread->accum_tb += (current_tb - start_tb);
 		new_thread->start_tb = current_tb;
 	}
-#endif
+#endif /* CONFIG_PPC64 */
+
+#ifdef CONFIG_PPC_BOOK3S_64
+	batch = &__get_cpu_var(ppc64_tlb_batch);
+	if (batch->active) {
+		current_thread_info()->local_flags |= _TLF_LAZY_MMU;
+		if (batch->index)
+			__flush_tlb_pending(batch);
+		batch->active = 0;
+	}
+#endif /* CONFIG_PPC_BOOK3S_64 */
 
 	local_irq_save(flags);
 
@@ -526,6 +539,14 @@ struct task_struct *__switch_to(struct t
 	hard_irq_disable();
 	last = _switch(old_thread, new_thread);
 
+#ifdef CONFIG_PPC_BOOK3S_64
+	if (current_thread_info()->local_flags & _TLF_LAZY_MMU) {
+		current_thread_info()->local_flags &= ~_TLF_LAZY_MMU;
+		batch = &__get_cpu_var(ppc64_tlb_batch);
+		batch->active = 1;
+	}
+#endif /* CONFIG_PPC_BOOK3S_64 */
+
 	local_irq_restore(flags);
 
 	return last;
Index: linux-2.6/arch/powerpc/mm/pgtable.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/pgtable.c
+++ linux-2.6/arch/powerpc/mm/pgtable.c
@@ -33,8 +33,6 @@
 
 #include "mmu_decl.h"
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 #ifdef CONFIG_SMP
 
 /*
@@ -43,7 +41,6 @@ DEFINE_PER_CPU(struct mmu_gather, mmu_ga
  * freeing a page table page that is being walked without locks
  */
 
-static DEFINE_PER_CPU(struct pte_freelist_batch *, pte_freelist_cur);
 static unsigned long pte_freelist_forced_free;
 
 struct pte_freelist_batch
@@ -97,12 +94,10 @@ static void pte_free_submit(struct pte_f
 
 void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift)
 {
-	/* This is safe since tlb_gather_mmu has disabled preemption */
-	struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
+	struct pte_freelist_batch **batchp = &tlb->arch.batch;
 	unsigned long pgf;
 
-	if (atomic_read(&tlb->mm->mm_users) < 2 ||
-	    cpumask_equal(mm_cpumask(tlb->mm), cpumask_of(smp_processor_id()))){
+	if (atomic_read(&tlb->mm->mm_users) < 2) {
 		pgtable_free(table, shift);
 		return;
 	}
@@ -124,10 +119,9 @@ void pgtable_free_tlb(struct mmu_gather 
 	}
 }
 
-void pte_free_finish(void)
+void pte_free_finish(struct mmu_gather *tlb)
 {
-	/* This is safe since tlb_gather_mmu has disabled preemption */
-	struct pte_freelist_batch **batchp = &__get_cpu_var(pte_freelist_cur);
+	struct pte_freelist_batch **batchp = &tlb->arch.batch;
 
 	if (*batchp == NULL)
 		return;
Index: linux-2.6/arch/powerpc/mm/tlb_hash64.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_hash64.c
+++ linux-2.6/arch/powerpc/mm/tlb_hash64.c
@@ -38,13 +38,11 @@ DEFINE_PER_CPU(struct ppc64_tlb_batch, p
  * neesd to be flushed. This function will either perform the flush
  * immediately or will batch it up if the current CPU has an active
  * batch on it.
- *
- * Must be called from within some kind of spinlock/non-preempt region...
  */
 void hpte_need_flush(struct mm_struct *mm, unsigned long addr,
 		     pte_t *ptep, unsigned long pte, int huge)
 {
-	struct ppc64_tlb_batch *batch = &__get_cpu_var(ppc64_tlb_batch);
+	struct ppc64_tlb_batch *batch = &get_cpu_var(ppc64_tlb_batch);
 	unsigned long vsid, vaddr;
 	unsigned int psize;
 	int ssize;
@@ -99,6 +97,7 @@ void hpte_need_flush(struct mm_struct *m
 	 */
 	if (!batch->active) {
 		flush_hash_page(vaddr, rpte, psize, ssize, 0);
+		put_cpu_var(ppc64_tlb_batch);
 		return;
 	}
 
@@ -127,6 +126,7 @@ void hpte_need_flush(struct mm_struct *m
 	batch->index = ++i;
 	if (i >= PPC64_TLB_BATCH_NR)
 		__flush_tlb_pending(batch);
+	put_cpu_var(ppc64_tlb_batch);
 }
 
 /*
@@ -155,7 +155,7 @@ void __flush_tlb_pending(struct ppc64_tl
 
 void tlb_flush(struct mmu_gather *tlb)
 {
-	struct ppc64_tlb_batch *tlbbatch = &__get_cpu_var(ppc64_tlb_batch);
+	struct ppc64_tlb_batch *tlbbatch = &get_cpu_var(ppc64_tlb_batch);
 
 	/* If there's a TLB batch pending, then we must flush it because the
 	 * pages are going to be freed and we really don't want to have a CPU
@@ -164,8 +164,10 @@ void tlb_flush(struct mmu_gather *tlb)
 	if (tlbbatch->index)
 		__flush_tlb_pending(tlbbatch);
 
+	put_cpu_var(ppc64_tlb_batch);
+
 	/* Push out batch of freed page tables */
-	pte_free_finish();
+	pte_free_finish(tlb);
 }
 
 /**
Index: linux-2.6/arch/powerpc/include/asm/thread_info.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/thread_info.h
+++ linux-2.6/arch/powerpc/include/asm/thread_info.h
@@ -139,10 +139,12 @@ static inline struct thread_info *curren
 #define TLF_NAPPING		0	/* idle thread enabled NAP mode */
 #define TLF_SLEEPING		1	/* suspend code enabled SLEEP mode */
 #define TLF_RESTORE_SIGMASK	2	/* Restore signal mask in do_signal */
+#define TLF_LAZY_MMU		3	/* tlb_batch is active */
 
 #define _TLF_NAPPING		(1 << TLF_NAPPING)
 #define _TLF_SLEEPING		(1 << TLF_SLEEPING)
 #define _TLF_RESTORE_SIGMASK	(1 << TLF_RESTORE_SIGMASK)
+#define _TLF_LAZY_MMU		(1 << TLF_LAZY_MMU)
 
 #ifndef __ASSEMBLY__
 #define HAVE_SET_RESTORE_SIGMASK	1
Index: linux-2.6/arch/powerpc/include/asm/pgalloc.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/pgalloc.h
+++ linux-2.6/arch/powerpc/include/asm/pgalloc.h
@@ -32,13 +32,13 @@ static inline void pte_free(struct mm_st
 
 #ifdef CONFIG_SMP
 extern void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift);
-extern void pte_free_finish(void);
+extern void pte_free_finish(struct mmu_gather *tlb);
 #else /* CONFIG_SMP */
 static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift)
 {
 	pgtable_free(table, shift);
 }
-static inline void pte_free_finish(void) { }
+static inline void pte_free_finish(struct mmu_gather *tlb) { }
 #endif /* !CONFIG_SMP */
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *ptepage,
Index: linux-2.6/arch/powerpc/mm/tlb_hash32.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_hash32.c
+++ linux-2.6/arch/powerpc/mm/tlb_hash32.c
@@ -73,7 +73,7 @@ void tlb_flush(struct mmu_gather *tlb)
 	}
 
 	/* Push out batch of freed page tables */
-	pte_free_finish();
+	pte_free_finish(tlb);
 }
 
 /*
Index: linux-2.6/arch/powerpc/mm/tlb_nohash.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_nohash.c
+++ linux-2.6/arch/powerpc/mm/tlb_nohash.c
@@ -301,7 +301,7 @@ void tlb_flush(struct mmu_gather *tlb)
 	flush_tlb_mm(tlb->mm);
 
 	/* Push out batch of freed page tables */
-	pte_free_finish();
+	pte_free_finish(tlb);
 }
 
 /*


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[PATCH 04/25] sparc: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-sparc-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 9142 bytes --]

Rework the sparc mmu_gather usage to conform to the new world order :-)

Sparc mmu_gather does two things:
 - tracks vaddrs to unhash
 - tracks pages to free

Split these two things like powerpc has done and keep the vaddrs
in per-cpu data structures and flush them on context switch.

The remaining bits can then use the generic mmu_gather.

Cc: David Miller <davem@davemloft.net>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/sparc/include/asm/pgalloc_64.h  |    3 +
 arch/sparc/include/asm/tlb_64.h      |   91 ++---------------------------------
 arch/sparc/include/asm/tlbflush_64.h |   12 +++-
 arch/sparc/mm/tlb.c                  |   42 +++++++++-------
 arch/sparc/mm/tsb.c                  |   15 +++--
 5 files changed, 51 insertions(+), 112 deletions(-)

Index: linux-2.6/arch/sparc/include/asm/pgalloc_64.h
===================================================================
--- linux-2.6.orig/arch/sparc/include/asm/pgalloc_64.h
+++ linux-2.6/arch/sparc/include/asm/pgalloc_64.h
@@ -78,4 +78,7 @@ static inline void check_pgt_cache(void)
 	quicklist_trim(0, NULL, 25, 16);
 }
 
+#define __pte_free_tlb(tlb, pte, addr)	pte_free((tlb)->mm, pte)
+#define __pmd_free_tlb(tlb, pmd, addr)	pmd_free((tlb)->mm, pmd)
+
 #endif /* _SPARC64_PGALLOC_H */
Index: linux-2.6/arch/sparc/include/asm/tlb_64.h
===================================================================
--- linux-2.6.orig/arch/sparc/include/asm/tlb_64.h
+++ linux-2.6/arch/sparc/include/asm/tlb_64.h
@@ -7,66 +7,11 @@
 #include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
 
-#define TLB_BATCH_NR	192
-
-/*
- * For UP we don't need to worry about TLB flush
- * and page free order so much..
- */
-#ifdef CONFIG_SMP
-  #define FREE_PTE_NR	506
-  #define tlb_fast_mode(bp) ((bp)->pages_nr == ~0U)
-#else
-  #define FREE_PTE_NR	1
-  #define tlb_fast_mode(bp) 1
-#endif
-
-struct mmu_gather {
-	struct mm_struct *mm;
-	unsigned int pages_nr;
-	unsigned int need_flush;
-	unsigned int fullmm;
-	unsigned int tlb_nr;
-	unsigned long vaddrs[TLB_BATCH_NR];
-	struct page *pages[FREE_PTE_NR];
-};
-
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 #ifdef CONFIG_SMP
 extern void smp_flush_tlb_pending(struct mm_struct *,
 				  unsigned long, unsigned long *);
 #endif
 
-extern void __flush_tlb_pending(unsigned long, unsigned long, unsigned long *);
-extern void flush_tlb_pending(void);
-
-static inline struct mmu_gather *tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
-{
-	struct mmu_gather *mp = &get_cpu_var(mmu_gathers);
-
-	BUG_ON(mp->tlb_nr);
-
-	mp->mm = mm;
-	mp->pages_nr = num_online_cpus() > 1 ? 0U : ~0U;
-	mp->fullmm = full_mm_flush;
-
-	return mp;
-}
-
-
-static inline void tlb_flush_mmu(struct mmu_gather *mp)
-{
-	if (!mp->fullmm)
-		flush_tlb_pending();
-	if (mp->need_flush) {
-		free_pages_and_swap_cache(mp->pages, mp->pages_nr);
-		mp->pages_nr = 0;
-		mp->need_flush = 0;
-	}
-
-}
-
 #ifdef CONFIG_SMP
 extern void smp_flush_tlb_mm(struct mm_struct *mm);
 #define do_flush_tlb_mm(mm) smp_flush_tlb_mm(mm)
@@ -74,38 +19,14 @@ extern void smp_flush_tlb_mm(struct mm_s
 #define do_flush_tlb_mm(mm) __flush_tlb_mm(CTX_HWBITS(mm->context), SECONDARY_CONTEXT)
 #endif
 
-static inline void tlb_finish_mmu(struct mmu_gather *mp, unsigned long start, unsigned long end)
-{
-	tlb_flush_mmu(mp);
-
-	if (mp->fullmm)
-		mp->fullmm = 0;
-
-	/* keep the page table cache within bounds */
-	check_pgt_cache();
-
-	put_cpu_var(mmu_gathers);
-}
-
-static inline void tlb_remove_page(struct mmu_gather *mp, struct page *page)
-{
-	if (tlb_fast_mode(mp)) {
-		free_page_and_swap_cache(page);
-		return;
-	}
-	mp->need_flush = 1;
-	mp->pages[mp->pages_nr++] = page;
-	if (mp->pages_nr >= FREE_PTE_NR)
-		tlb_flush_mmu(mp);
-}
-
-#define tlb_remove_tlb_entry(mp,ptep,addr) do { } while (0)
-#define pte_free_tlb(mp, ptepage, addr) pte_free((mp)->mm, ptepage)
-#define pmd_free_tlb(mp, pmdp, addr) pmd_free((mp)->mm, pmdp)
-#define pud_free_tlb(tlb,pudp, addr) __pud_free_tlb(tlb,pudp,addr)
+extern void __flush_tlb_pending(unsigned long, unsigned long, unsigned long *);
+extern void flush_tlb_pending(void);
 
-#define tlb_migrate_finish(mm)	do { } while (0)
 #define tlb_start_vma(tlb, vma) do { } while (0)
 #define tlb_end_vma(tlb, vma)	do { } while (0)
+#define __tlb_remove_tlb_entry(tlb, ptep, address) do { } while (0)
+#define tlb_flush(tlb)	flush_tlb_pending()
+
+#include <asm-generic/tlb.h>
 
 #endif /* _SPARC64_TLB_H */
Index: linux-2.6/arch/sparc/include/asm/tlbflush_64.h
===================================================================
--- linux-2.6.orig/arch/sparc/include/asm/tlbflush_64.h
+++ linux-2.6/arch/sparc/include/asm/tlbflush_64.h
@@ -5,9 +5,17 @@
 #include <asm/mmu_context.h>
 
 /* TSB flush operations. */
-struct mmu_gather;
+
+#define TLB_BATCH_NR	192
+
+struct tlb_batch {
+	struct mm_struct *mm;
+	unsigned long tlb_nr;
+	unsigned long vaddrs[TLB_BATCH_NR];
+};
+
 extern void flush_tsb_kernel_range(unsigned long start, unsigned long end);
-extern void flush_tsb_user(struct mmu_gather *mp);
+extern void flush_tsb_user(struct tlb_batch *tb);
 
 /* TLB flush operations. */
 
Index: linux-2.6/arch/sparc/mm/tlb.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/tlb.c
+++ linux-2.6/arch/sparc/mm/tlb.c
@@ -19,33 +19,33 @@
 
 /* Heavily inspired by the ppc64 code.  */
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
+static DEFINE_PER_CPU(struct tlb_batch, tlb_batch);
 
 void flush_tlb_pending(void)
 {
-	struct mmu_gather *mp = &get_cpu_var(mmu_gathers);
+	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
 
-	if (mp->tlb_nr) {
-		flush_tsb_user(mp);
+	if (tb->tlb_nr) {
+		flush_tsb_user(tb);
 
-		if (CTX_VALID(mp->mm->context)) {
+		if (CTX_VALID(tb->mm->context)) {
 #ifdef CONFIG_SMP
-			smp_flush_tlb_pending(mp->mm, mp->tlb_nr,
-					      &mp->vaddrs[0]);
+			smp_flush_tlb_pending(tb->mm, tb->tlb_nr,
+					      &tb->vaddrs[0]);
 #else
-			__flush_tlb_pending(CTX_HWBITS(mp->mm->context),
-					    mp->tlb_nr, &mp->vaddrs[0]);
+			__flush_tlb_pending(CTX_HWBITS(tb->mm->context),
+					    tb->tlb_nr, &tb->vaddrs[0]);
 #endif
 		}
-		mp->tlb_nr = 0;
+		tb->tlb_nr = 0;
 	}
 
-	put_cpu_var(mmu_gathers);
+	put_cpu_var(tlb_batch);
 }
 
 void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr, pte_t *ptep, pte_t orig)
 {
-	struct mmu_gather *mp = &__get_cpu_var(mmu_gathers);
+	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
 	unsigned long nr;
 
 	vaddr &= PAGE_MASK;
@@ -77,21 +77,27 @@ void tlb_batch_add(struct mm_struct *mm,
 
 no_cache_flush:
 
-	if (mp->fullmm)
+	/*
+	if (tb->fullmm) {
+		put_cpu_var(tlb_batch);
 		return;
+	}
+	*/
 
-	nr = mp->tlb_nr;
+	nr = tb->tlb_nr;
 
-	if (unlikely(nr != 0 && mm != mp->mm)) {
+	if (unlikely(nr != 0 && mm != tb->mm)) {
 		flush_tlb_pending();
 		nr = 0;
 	}
 
 	if (nr == 0)
-		mp->mm = mm;
+		tb->mm = mm;
 
-	mp->vaddrs[nr] = vaddr;
-	mp->tlb_nr = ++nr;
+	tb->vaddrs[nr] = vaddr;
+	tb->tlb_nr = ++nr;
 	if (nr >= TLB_BATCH_NR)
 		flush_tlb_pending();
+
+	put_cpu_var(tlb_batch);
 }
Index: linux-2.6/arch/sparc/mm/tsb.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/tsb.c
+++ linux-2.6/arch/sparc/mm/tsb.c
@@ -47,12 +47,13 @@ void flush_tsb_kernel_range(unsigned lon
 	}
 }
 
-static void __flush_tsb_one(struct mmu_gather *mp, unsigned long hash_shift, unsigned long tsb, unsigned long nentries)
+static void __flush_tsb_one(struct tlb_batch *tb, unsigned long hash_shift,
+			    unsigned long tsb, unsigned long nentries)
 {
 	unsigned long i;
 
-	for (i = 0; i < mp->tlb_nr; i++) {
-		unsigned long v = mp->vaddrs[i];
+	for (i = 0; i < tb->tlb_nr; i++) {
+		unsigned long v = tb->vaddrs[i];
 		unsigned long tag, ent, hash;
 
 		v &= ~0x1UL;
@@ -65,9 +66,9 @@ static void __flush_tsb_one(struct mmu_g
 	}
 }
 
-void flush_tsb_user(struct mmu_gather *mp)
+void flush_tsb_user(struct tlb_batch *tb)
 {
-	struct mm_struct *mm = mp->mm;
+	struct mm_struct *mm = tb->mm;
 	unsigned long nentries, base, flags;
 
 	spin_lock_irqsave(&mm->context.lock, flags);
@@ -76,7 +77,7 @@ void flush_tsb_user(struct mmu_gather *m
 	nentries = mm->context.tsb_block[MM_TSB_BASE].tsb_nentries;
 	if (tlb_type == cheetah_plus || tlb_type == hypervisor)
 		base = __pa(base);
-	__flush_tsb_one(mp, PAGE_SHIFT, base, nentries);
+	__flush_tsb_one(tb, PAGE_SHIFT, base, nentries);
 
 #ifdef CONFIG_HUGETLB_PAGE
 	if (mm->context.tsb_block[MM_TSB_HUGE].tsb) {
@@ -84,7 +85,7 @@ void flush_tsb_user(struct mmu_gather *m
 		nentries = mm->context.tsb_block[MM_TSB_HUGE].tsb_nentries;
 		if (tlb_type == cheetah_plus || tlb_type == hypervisor)
 			base = __pa(base);
-		__flush_tsb_one(mp, HPAGE_SHIFT, base, nentries);
+		__flush_tsb_one(tb, HPAGE_SHIFT, base, nentries);
 	}
 #endif
 	spin_unlock_irqrestore(&mm->context.lock, flags);


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Re: [PATCH 04/25] sparc: Preemptible mmu_gather

[David Miller]

From: Peter Zijlstra <a.p.zijlstra@chello.nl>
Date: Tue, 25 Jan 2011 18:31:15 +0100

> Rework the sparc mmu_gather usage to conform to the new world order :-)
> 
> Sparc mmu_gather does two things:
>  - tracks vaddrs to unhash
>  - tracks pages to free
> 
> Split these two things like powerpc has done and keep the vaddrs
> in per-cpu data structures and flush them on context switch.
> 
> The remaining bits can then use the generic mmu_gather.
> 
> Cc: David Miller <davem@davemloft.net>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Acked-by: David S. Miller <davem@davemloft.net>

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[PATCH 05/25] s390: preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: martin_schwidefsky-s390-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 2932 bytes --]

From: Martin Schwidefsky <schwidefsky@de.ibm.com>

Adapt the stand-alone s390 mmu_gather implementation to the new
preemptible mmu_gather interface.

Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
LKML-Reference: <20101126145410.881573395@chello.nl>
---
 arch/s390/include/asm/tlb.h |   43 +++++++++++++++++++++++++------------------
 1 file changed, 25 insertions(+), 18 deletions(-)

Index: linux-2.6/arch/s390/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/s390/include/asm/tlb.h
+++ linux-2.6/arch/s390/include/asm/tlb.h
@@ -28,44 +28,50 @@
 #include <asm/smp.h>
 #include <asm/tlbflush.h>
 
-#ifndef CONFIG_SMP
-#define TLB_NR_PTRS	1
-#else
-#define TLB_NR_PTRS	508
-#endif
-
 struct mmu_gather {
 	struct mm_struct *mm;
 	unsigned int fullmm;
 	unsigned int nr_ptes;
 	unsigned int nr_pxds;
-	void *array[TLB_NR_PTRS];
+	unsigned int max;
+	void **array;
+	void *local[8];
 };
 
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
-static inline struct mmu_gather *tlb_gather_mmu(struct mm_struct *mm,
-						unsigned int full_mm_flush)
+static inline void __tlb_alloc_page(struct mmu_gather *tlb)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
+	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+
+	if (addr) {
+		tlb->array = (void *) addr;
+		tlb->max = PAGE_SIZE / sizeof(void *);
+	}
+}
 
+static inline void tlb_gather_mmu(struct mmu_gather *tlb,
+				  struct mm_struct *mm,
+				  unsigned int full_mm_flush)
+{
 	tlb->mm = mm;
+	tlb->max = ARRAY_SIZE(tlb->local);
+	tlb->array = tlb->local;
 	tlb->fullmm = full_mm_flush;
-	tlb->nr_ptes = 0;
-	tlb->nr_pxds = TLB_NR_PTRS;
 	if (tlb->fullmm)
 		__tlb_flush_mm(mm);
-	return tlb;
+	else
+		__tlb_alloc_page(tlb);
+	tlb->nr_ptes = 0;
+	tlb->nr_pxds = tlb->max;
 }
 
 static inline void tlb_flush_mmu(struct mmu_gather *tlb,
 				 unsigned long start, unsigned long end)
 {
-	if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < TLB_NR_PTRS))
+	if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < tlb->max))
 		__tlb_flush_mm(tlb->mm);
 	while (tlb->nr_ptes > 0)
 		page_table_free_rcu(tlb->mm, tlb->array[--tlb->nr_ptes]);
-	while (tlb->nr_pxds < TLB_NR_PTRS)
+	while (tlb->nr_pxds < tlb->max)
 		crst_table_free_rcu(tlb->mm, tlb->array[tlb->nr_pxds++]);
 }
 
@@ -79,7 +85,8 @@ static inline void tlb_finish_mmu(struct
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	put_cpu_var(mmu_gathers);
+	if (tlb->array != tlb->local)
+		free_pages((unsigned long) tlb->array, 0);
 }
 
 /*


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[PATCH 06/25] arm: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-arm-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 1407 bytes --]

Fix up the arm mmu_gahter code to conform to the new API.

Cc: Russell King <rmk@arm.linux.org.uk>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/arm/include/asm/tlb.h |   12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

Index: linux-2.6/arch/arm/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/arm/include/asm/tlb.h
+++ linux-2.6/arch/arm/include/asm/tlb.h
@@ -40,17 +40,11 @@ struct mmu_gather {
 	unsigned long		range_end;
 };
 
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
-static inline struct mmu_gather *
-tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
-
 	tlb->mm = mm;
 	tlb->fullmm = full_mm_flush;
-
-	return tlb;
 }
 
 static inline void
@@ -61,8 +55,6 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
-
-	put_cpu_var(mmu_gathers);
 }
 
 /*


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[PATCH 07/25] sh: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-sh-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 1599 bytes --]

Fix up the sh mmu_gahter code to conform to the new API.

Cc: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/sh/include/asm/tlb.h |   12 ++----------
 1 file changed, 2 insertions(+), 10 deletions(-)

Index: linux-2.6/arch/sh/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/sh/include/asm/tlb.h
+++ linux-2.6/arch/sh/include/asm/tlb.h
@@ -23,8 +23,6 @@ struct mmu_gather {
 	unsigned long		start, end;
 };
 
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 static inline void init_tlb_gather(struct mmu_gather *tlb)
 {
 	tlb->start = TASK_SIZE;
@@ -36,17 +34,13 @@ static inline void init_tlb_gather(struc
 	}
 }
 
-static inline struct mmu_gather *
-tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
-
 	tlb->mm = mm;
 	tlb->fullmm = full_mm_flush;
 
 	init_tlb_gather(tlb);
-
-	return tlb;
 }
 
 static inline void
@@ -57,8 +51,6 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
-
-	put_cpu_var(mmu_gathers);
 }
 
 static inline void


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[PATCH 08/25] um: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-um-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 1872 bytes --]

Fix up the um mmu_gather code to conform to the new API.

Cc: Jeff Dike <jdike@addtoit.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/um/include/asm/tlb.h |   16 ++--------------
 1 file changed, 2 insertions(+), 14 deletions(-)

Index: linux-2.6/arch/um/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/um/include/asm/tlb.h
+++ linux-2.6/arch/um/include/asm/tlb.h
@@ -22,9 +22,6 @@ struct mmu_gather {
 	unsigned int		fullmm; /* non-zero means full mm flush */
 };
 
-/* Users of the generic TLB shootdown code must declare this storage space. */
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 static inline void __tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep,
 					  unsigned long address)
 {
@@ -47,20 +44,13 @@ static inline void init_tlb_gather(struc
 	}
 }
 
-/* tlb_gather_mmu
- *	Return a pointer to an initialized struct mmu_gather.
- */
-static inline struct mmu_gather *
-tlb_gather_mmu(struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
-
 	tlb->mm = mm;
 	tlb->fullmm = full_mm_flush;
 
 	init_tlb_gather(tlb);
-
-	return tlb;
 }
 
 extern void flush_tlb_mm_range(struct mm_struct *mm, unsigned long start,
@@ -87,8 +77,6 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
-
-	put_cpu_var(mmu_gathers);
 }
 
 /* tlb_remove_page


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[PATCH 09/25] ia64: Preemptible mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-ia64-preemptible_mmu_gather.patch --]
[-- Type: text/plain, Size: 3744 bytes --]

Fix up the ia64 mmu_gather code to conform to the new API.

Cc: Tony Luck <tony.luck@intel.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/ia64/include/asm/tlb.h |   41 +++++++++++++++++++++++++----------------
 1 file changed, 25 insertions(+), 16 deletions(-)

Index: linux-2.6/arch/ia64/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/ia64/include/asm/tlb.h
+++ linux-2.6/arch/ia64/include/asm/tlb.h
@@ -47,21 +47,21 @@
 #include <asm/machvec.h>
 
 #ifdef CONFIG_SMP
-# define FREE_PTE_NR		2048
 # define tlb_fast_mode(tlb)	((tlb)->nr == ~0U)
 #else
-# define FREE_PTE_NR		0
 # define tlb_fast_mode(tlb)	(1)
 #endif
 
 struct mmu_gather {
 	struct mm_struct	*mm;
 	unsigned int		nr;		/* == ~0U => fast mode */
+	unsigned int		max;
 	unsigned char		fullmm;		/* non-zero means full mm flush */
 	unsigned char		need_flush;	/* really unmapped some PTEs? */
 	unsigned long		start_addr;
 	unsigned long		end_addr;
-	struct page 		*pages[FREE_PTE_NR];
+	struct page		**pages;
+	struct page		*local[8];
 };
 
 struct ia64_tr_entry {
@@ -90,9 +90,6 @@ extern struct ia64_tr_entry *ia64_idtrs[
 #define RR_RID_MASK	0x00000000ffffff00L
 #define RR_TO_RID(val) 	((val >> 8) & 0xffffff)
 
-/* Users of the generic TLB shootdown code must declare this storage space. */
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * Flush the TLB for address range START to END and, if not in fast mode, release the
  * freed pages that where gathered up to this point.
@@ -147,15 +144,23 @@ ia64_tlb_flush_mmu (struct mmu_gather *t
 	}
 }
 
-/*
- * Return a pointer to an initialized struct mmu_gather.
- */
-static inline struct mmu_gather *
-tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void __tlb_alloc_page(struct mmu_gather *tlb)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
+	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+
+	if (addr) {
+		tlb->pages = (void *)addr;
+		tlb->max = PAGE_SIZE / sizeof(void *);
+	}
+}
 
+
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
+{
 	tlb->mm = mm;
+	tlb->max = ARRAY_SIZE(tlb->local);
+	tlb->pages = tlb->local;
 	/*
 	 * Use fast mode if only 1 CPU is online.
 	 *
@@ -172,7 +177,6 @@ tlb_gather_mmu (struct mm_struct *mm, un
 	tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
 	tlb->fullmm = full_mm_flush;
 	tlb->start_addr = ~0UL;
-	return tlb;
 }
 
 /*
@@ -180,7 +184,7 @@ tlb_gather_mmu (struct mm_struct *mm, un
  * collected.
  */
 static inline void
-tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
+tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
 	/*
 	 * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
@@ -191,7 +195,8 @@ tlb_finish_mmu (struct mmu_gather *tlb, 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	put_cpu_var(mmu_gathers);
+	if (tlb->pages != tlb->local)
+		free_pages((unsigned long)tlb->pages, 0);
 }
 
 /*
@@ -208,8 +213,12 @@ tlb_remove_page (struct mmu_gather *tlb,
 		free_page_and_swap_cache(page);
 		return;
 	}
+
+	if (!tlb->nr && tlb->pages == tlb->local)
+		__tlb_alloc_page(tlb);
+
 	tlb->pages[tlb->nr++] = page;
-	if (tlb->nr >= FREE_PTE_NR)
+	if (tlb->nr >= tlb->max)
 		ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
 }
 


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Re: [PATCH 09/25] ia64: Preemptible mmu_gather

[Tony Luck]

On Tue, Jan 25, 2011 at 9:31 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>  struct mmu_gather {
>        struct mm_struct        *mm;
>        unsigned int            nr;             /* == ~0U => fast mode */
> +       unsigned int            max;
>        unsigned char           fullmm;         /* non-zero means full mm flush */
>        unsigned char           need_flush;     /* really unmapped some PTEs? */
>        unsigned long           start_addr;
>        unsigned long           end_addr;
> -       struct page             *pages[FREE_PTE_NR];
> +       struct page             **pages;
> +       struct page             *local[8];
>  };

Overall it looks OK - builds, boots & runs too. One question about
the above bit ... why "8" elements in the local[] array?  This ought to be
a #define, maybe with a comment explaining the significance. It doesn't
seem to fill out struct mmu_gather to some "nice" size.  I can't think
of why batching 8 at a time (in the fallback cannot allocate **pages case)
is a good number. So is there some science to the choice, or did you
pluck 8 out of the air?

Thanks

-Tony

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Re: [PATCH 09/25] ia64: Preemptible mmu_gather

[Peter Zijlstra]

On Tue, 2011-01-25 at 12:12 -0800, Tony Luck wrote:
> On Tue, Jan 25, 2011 at 9:31 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> >  struct mmu_gather {
> >        struct mm_struct        *mm;
> >        unsigned int            nr;             /* == ~0U => fast mode */
> > +       unsigned int            max;
> >        unsigned char           fullmm;         /* non-zero means full mm flush */
> >        unsigned char           need_flush;     /* really unmapped some PTEs? */
> >        unsigned long           start_addr;
> >        unsigned long           end_addr;
> > -       struct page             *pages[FREE_PTE_NR];
> > +       struct page             **pages;
> > +       struct page             *local[8];
> >  };
> 
> Overall it looks OK - builds, boots & runs too. One question about
> the above bit ... why "8" elements in the local[] array?  This ought to be
> a #define, maybe with a comment explaining the significance. It doesn't
> seem to fill out struct mmu_gather to some "nice" size.  I can't think
> of why batching 8 at a time (in the fallback cannot allocate **pages case)
> is a good number. So is there some science to the choice, or did you
> pluck 8 out of the air? 

Yeah, pretty much a random number small enough to make struct mmu_gather
fit on stack, the reason its not 1 is that a few more entries increase
performance a little and freeing more pages increases the chance the
page allocation works next time around.


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Re: [PATCH 09/25] ia64: Preemptible mmu_gather

[Tony Luck]

> Yeah, pretty much a random number small enough to make struct mmu_gather
> fit on stack, the reason its not 1 is that a few more entries increase
> performance a little and freeing more pages increases the chance the
> page allocation works next time around.

Okay ... then could you swap out your part 09/25 for this version that
has a #define and a comment.  You can add

Acked-by: Tony Luck <tony.luck@intel.com>

-Tony

---

diff --git a/arch/ia64/include/asm/tlb.h b/arch/ia64/include/asm/tlb.h
index 23cce99..ec4ca06 100644
--- a/arch/ia64/include/asm/tlb.h
+++ b/arch/ia64/include/asm/tlb.h
@@ -47,21 +47,27 @@
 #include <asm/machvec.h>
 
 #ifdef CONFIG_SMP
-# define FREE_PTE_NR		2048
 # define tlb_fast_mode(tlb)	((tlb)->nr == ~0U)
 #else
-# define FREE_PTE_NR		0
 # define tlb_fast_mode(tlb)	(1)
 #endif
 
+/*
+ * If we can't allocate a page to make a big batch of page pointers
+ * to work on, then just handle a few from the on-stack structure.
+ */
+#define	IA64_GATHER_BUNDLE	8
+
 struct mmu_gather {
 	struct mm_struct	*mm;
 	unsigned int		nr;		/* == ~0U => fast mode */
+	unsigned int		max;
 	unsigned char		fullmm;		/* non-zero means full mm flush */
 	unsigned char		need_flush;	/* really unmapped some PTEs? */
 	unsigned long		start_addr;
 	unsigned long		end_addr;
-	struct page 		*pages[FREE_PTE_NR];
+	struct page		**pages;
+	struct page		*local[IA64_GATHER_BUNDLE];
 };
 
 struct ia64_tr_entry {
@@ -90,9 +96,6 @@ extern struct ia64_tr_entry *ia64_idtrs[NR_CPUS];
 #define RR_RID_MASK	0x00000000ffffff00L
 #define RR_TO_RID(val) 	((val >> 8) & 0xffffff)
 
-/* Users of the generic TLB shootdown code must declare this storage space. */
-DECLARE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * Flush the TLB for address range START to END and, if not in fast mode, release the
  * freed pages that where gathered up to this point.
@@ -147,15 +150,23 @@ ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long e
 	}
 }
 
-/*
- * Return a pointer to an initialized struct mmu_gather.
- */
-static inline struct mmu_gather *
-tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
+static inline void __tlb_alloc_page(struct mmu_gather *tlb)
 {
-	struct mmu_gather *tlb = &get_cpu_var(mmu_gathers);
+	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+
+	if (addr) {
+		tlb->pages = (void *)addr;
+		tlb->max = PAGE_SIZE / sizeof(void *);
+	}
+}
 
+
+static inline void
+tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
+{
 	tlb->mm = mm;
+	tlb->max = ARRAY_SIZE(tlb->local);
+	tlb->pages = tlb->local;
 	/*
 	 * Use fast mode if only 1 CPU is online.
 	 *
@@ -172,7 +183,6 @@ tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
 	tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
 	tlb->fullmm = full_mm_flush;
 	tlb->start_addr = ~0UL;
-	return tlb;
 }
 
 /*
@@ -180,7 +190,7 @@ tlb_gather_mmu (struct mm_struct *mm, unsigned int full_mm_flush)
  * collected.
  */
 static inline void
-tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
+tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
 	/*
 	 * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
@@ -191,7 +201,8 @@ tlb_finish_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	put_cpu_var(mmu_gathers);
+	if (tlb->pages != tlb->local)
+		free_pages((unsigned long)tlb->pages, 0);
 }
 
 /*
@@ -208,8 +219,12 @@ tlb_remove_page (struct mmu_gather *tlb, struct page *page)
 		free_page_and_swap_cache(page);
 		return;
 	}
+
+	if (!tlb->nr && tlb->pages == tlb->local)
+		__tlb_alloc_page(tlb);
+
 	tlb->pages[tlb->nr++] = page;
-	if (tlb->nr >= FREE_PTE_NR)
+	if (tlb->nr >= tlb->max)
 		ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
 }
 

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Re: [PATCH 09/25] ia64: Preemptible mmu_gather

[Peter Zijlstra]

On Tue, 2011-01-25 at 13:23 -0800, tony.luck@intel.com wrote:
> Okay ... then could you swap out your part 09/25 for this version that
> has a #define and a comment.  You can add
> 
> Acked-by: Tony Luck <tony.luck@intel.com>
> 
Thanks Tony!

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[PATCH 10/25] mm: Now that all old mmu_gather code is gone, remove the storage

[Peter Zijlstra]

[-- Attachment #1: arch-remove-mmu_gather.patch --]
[-- Type: text/plain, Size: 9151 bytes --]

XXX fold all the mmu_gather preempt patches into one for submission

Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/alpha/mm/init.c      |    2 --
 arch/arm/mm/mmu.c         |    2 --
 arch/avr32/mm/init.c      |    2 --
 arch/cris/mm/init.c       |    2 --
 arch/frv/mm/init.c        |    2 --
 arch/ia64/mm/init.c       |    2 --
 arch/m32r/mm/init.c       |    2 --
 arch/m68k/mm/init.c       |    2 --
 arch/microblaze/mm/init.c |    2 --
 arch/mips/mm/init.c       |    2 --
 arch/mn10300/mm/init.c    |    2 --
 arch/parisc/mm/init.c     |    2 --
 arch/s390/mm/pgtable.c    |    1 -
 arch/score/mm/init.c      |    2 --
 arch/sh/mm/init.c         |    1 -
 arch/sparc/mm/init_32.c   |    2 --
 arch/tile/mm/init.c       |    2 --
 arch/um/kernel/smp.c      |    3 ---
 arch/x86/mm/init.c        |    2 --
 arch/xtensa/mm/mmu.c      |    2 --
 20 files changed, 39 deletions(-)

Index: linux-2.6/arch/alpha/mm/init.c
===================================================================
--- linux-2.6.orig/arch/alpha/mm/init.c
+++ linux-2.6/arch/alpha/mm/init.c
@@ -32,8 +32,6 @@
 #include <asm/console.h>
 #include <asm/tlb.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 extern void die_if_kernel(char *,struct pt_regs *,long);
 
 static struct pcb_struct original_pcb;
Index: linux-2.6/arch/arm/mm/mmu.c
===================================================================
--- linux-2.6.orig/arch/arm/mm/mmu.c
+++ linux-2.6/arch/arm/mm/mmu.c
@@ -31,8 +31,6 @@
 
 #include "mm.h"
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * empty_zero_page is a special page that is used for
  * zero-initialized data and COW.
Index: linux-2.6/arch/avr32/mm/init.c
===================================================================
--- linux-2.6.orig/arch/avr32/mm/init.c
+++ linux-2.6/arch/avr32/mm/init.c
@@ -25,8 +25,6 @@
 #include <asm/setup.h>
 #include <asm/sections.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 pgd_t swapper_pg_dir[PTRS_PER_PGD] __page_aligned_data;
 
 struct page *empty_zero_page;
Index: linux-2.6/arch/cris/mm/init.c
===================================================================
--- linux-2.6.orig/arch/cris/mm/init.c
+++ linux-2.6/arch/cris/mm/init.c
@@ -13,8 +13,6 @@
 #include <linux/bootmem.h>
 #include <asm/tlb.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 unsigned long empty_zero_page;
 
 extern char _stext, _edata, _etext; /* From linkerscript */
Index: linux-2.6/arch/frv/mm/init.c
===================================================================
--- linux-2.6.orig/arch/frv/mm/init.c
+++ linux-2.6/arch/frv/mm/init.c
@@ -41,8 +41,6 @@
 
 #undef DEBUG
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * BAD_PAGE is the page that is used for page faults when linux
  * is out-of-memory. Older versions of linux just did a
Index: linux-2.6/arch/ia64/mm/init.c
===================================================================
--- linux-2.6.orig/arch/ia64/mm/init.c
+++ linux-2.6/arch/ia64/mm/init.c
@@ -36,8 +36,6 @@
 #include <asm/mca.h>
 #include <asm/paravirt.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 extern void ia64_tlb_init (void);
 
 unsigned long MAX_DMA_ADDRESS = PAGE_OFFSET + 0x100000000UL;
Index: linux-2.6/arch/m32r/mm/init.c
===================================================================
--- linux-2.6.orig/arch/m32r/mm/init.c
+++ linux-2.6/arch/m32r/mm/init.c
@@ -35,8 +35,6 @@ extern char __init_begin, __init_end;
 
 pgd_t swapper_pg_dir[1024];
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * Cache of MMU context last used.
  */
Index: linux-2.6/arch/m68k/mm/init.c
===================================================================
--- linux-2.6.orig/arch/m68k/mm/init.c
+++ linux-2.6/arch/m68k/mm/init.c
@@ -32,8 +32,6 @@
 #include <asm/sections.h>
 #include <asm/tlb.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 pg_data_t pg_data_map[MAX_NUMNODES];
 EXPORT_SYMBOL(pg_data_map);
 
Index: linux-2.6/arch/microblaze/mm/init.c
===================================================================
--- linux-2.6.orig/arch/microblaze/mm/init.c
+++ linux-2.6/arch/microblaze/mm/init.c
@@ -32,8 +32,6 @@ unsigned int __page_offset;
 EXPORT_SYMBOL(__page_offset);
 
 #else
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 static int init_bootmem_done;
 #endif /* CONFIG_MMU */
 
Index: linux-2.6/arch/mips/mm/init.c
===================================================================
--- linux-2.6.orig/arch/mips/mm/init.c
+++ linux-2.6/arch/mips/mm/init.c
@@ -64,8 +64,6 @@
 
 #endif /* CONFIG_MIPS_MT_SMTC */
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /*
  * We have up to 8 empty zeroed pages so we can map one of the right colour
  * when needed.  This is necessary only on R4000 / R4400 SC and MC versions
Index: linux-2.6/arch/mn10300/mm/init.c
===================================================================
--- linux-2.6.orig/arch/mn10300/mm/init.c
+++ linux-2.6/arch/mn10300/mm/init.c
@@ -37,8 +37,6 @@
 #include <asm/tlb.h>
 #include <asm/sections.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 unsigned long highstart_pfn, highend_pfn;
 
 #ifdef CONFIG_MN10300_HAS_ATOMIC_OPS_UNIT
Index: linux-2.6/arch/parisc/mm/init.c
===================================================================
--- linux-2.6.orig/arch/parisc/mm/init.c
+++ linux-2.6/arch/parisc/mm/init.c
@@ -31,8 +31,6 @@
 #include <asm/mmzone.h>
 #include <asm/sections.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 extern int  data_start;
 
 #ifdef CONFIG_DISCONTIGMEM
Index: linux-2.6/arch/s390/mm/pgtable.c
===================================================================
--- linux-2.6.orig/arch/s390/mm/pgtable.c
+++ linux-2.6/arch/s390/mm/pgtable.c
@@ -36,7 +36,6 @@ struct rcu_table_freelist {
 	((PAGE_SIZE - sizeof(struct rcu_table_freelist)) \
 	  / sizeof(unsigned long))
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 static DEFINE_PER_CPU(struct rcu_table_freelist *, rcu_table_freelist);
 
 static void __page_table_free(struct mm_struct *mm, unsigned long *table);
Index: linux-2.6/arch/score/mm/init.c
===================================================================
--- linux-2.6.orig/arch/score/mm/init.c
+++ linux-2.6/arch/score/mm/init.c
@@ -38,8 +38,6 @@
 #include <asm/sections.h>
 #include <asm/tlb.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 unsigned long empty_zero_page;
 EXPORT_SYMBOL_GPL(empty_zero_page);
 
Index: linux-2.6/arch/sh/mm/init.c
===================================================================
--- linux-2.6.orig/arch/sh/mm/init.c
+++ linux-2.6/arch/sh/mm/init.c
@@ -28,7 +28,6 @@
 #include <asm/cache.h>
 #include <asm/sizes.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
 pgd_t swapper_pg_dir[PTRS_PER_PGD];
 
 void __init generic_mem_init(void)
Index: linux-2.6/arch/sparc/mm/init_32.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/init_32.c
+++ linux-2.6/arch/sparc/mm/init_32.c
@@ -37,8 +37,6 @@
 #include <asm/prom.h>
 #include <asm/leon.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 unsigned long *sparc_valid_addr_bitmap;
 EXPORT_SYMBOL(sparc_valid_addr_bitmap);
 
Index: linux-2.6/arch/tile/mm/init.c
===================================================================
--- linux-2.6.orig/arch/tile/mm/init.c
+++ linux-2.6/arch/tile/mm/init.c
@@ -71,8 +71,6 @@
 unsigned long VMALLOC_RESERVE = CONFIG_VMALLOC_RESERVE;
 #endif
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 /* Create an L2 page table */
 static pte_t * __init alloc_pte(void)
 {
Index: linux-2.6/arch/um/kernel/smp.c
===================================================================
--- linux-2.6.orig/arch/um/kernel/smp.c
+++ linux-2.6/arch/um/kernel/smp.c
@@ -7,9 +7,6 @@
 #include "asm/pgalloc.h"
 #include "asm/tlb.h"
 
-/* For some reason, mmu_gathers are referenced when CONFIG_SMP is off. */
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 #ifdef CONFIG_SMP
 
 #include "linux/sched.h"
Index: linux-2.6/arch/x86/mm/init.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/init.c
+++ linux-2.6/arch/x86/mm/init.c
@@ -16,8 +16,6 @@
 #include <asm/tlb.h>
 #include <asm/proto.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 unsigned long __initdata e820_table_start;
 unsigned long __meminitdata e820_table_end;
 unsigned long __meminitdata e820_table_top;
Index: linux-2.6/arch/xtensa/mm/mmu.c
===================================================================
--- linux-2.6.orig/arch/xtensa/mm/mmu.c
+++ linux-2.6/arch/xtensa/mm/mmu.c
@@ -14,8 +14,6 @@
 #include <asm/mmu_context.h>
 #include <asm/page.h>
 
-DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
-
 void __init paging_init(void)
 {
 	memset(swapper_pg_dir, 0, PAGE_SIZE);


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[PATCH 11/25] mm, powerpc: Move the RCU page-table freeing into generic code

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm_powerpc-move_the_rcu_page-table_freeing_into.patch --]
[-- Type: text/plain, Size: 12846 bytes --]

In case other architectures require RCU freed page-tables to implement
gup_fast() and software filled hashes and similar things, provide the
means to do so by moving the logic into generic code.

Requested-by: David Miller <davem@davemloft.net>
Cc: Benjamin Herrenschmidt <benh@kernel.crashing.org>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/Kconfig                       |    3 +
 arch/powerpc/Kconfig               |    1 
 arch/powerpc/include/asm/pgalloc.h |   21 ++++++-
 arch/powerpc/include/asm/tlb.h     |   10 ---
 arch/powerpc/mm/pgtable.c          |   98 -------------------------------------
 arch/powerpc/mm/tlb_hash32.c       |    3 -
 arch/powerpc/mm/tlb_hash64.c       |    3 -
 arch/powerpc/mm/tlb_nohash.c       |    3 -
 include/asm-generic/tlb.h          |   57 +++++++++++++++++++--
 mm/memory.c                        |   77 +++++++++++++++++++++++++++++
 10 files changed, 151 insertions(+), 125 deletions(-)

Index: linux-2.6/arch/powerpc/include/asm/pgalloc.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/pgalloc.h
+++ linux-2.6/arch/powerpc/include/asm/pgalloc.h
@@ -31,14 +31,29 @@ static inline void pte_free(struct mm_st
 #endif
 
 #ifdef CONFIG_SMP
-extern void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift);
-extern void pte_free_finish(struct mmu_gather *tlb);
+struct mmu_gather;
+extern void tlb_remove_table(struct mmu_gather *, void *);
+
+static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, int shift)
+{
+	unsigned long pgf = (unsigned long)table;
+	BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
+	pgf |= shift;
+	tlb_remove_table(tlb, (void *)pgf);
+}
+
+static inline void __tlb_remove_table(void *_table)
+{
+	void *table = (void *)((unsigned long)_table & ~MAX_PGTABLE_INDEX_SIZE);
+	unsigned shift = (unsigned long)_table & MAX_PGTABLE_INDEX_SIZE;
+
+	pgtable_free(table, shift);
+}
 #else /* CONFIG_SMP */
 static inline void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift)
 {
 	pgtable_free(table, shift);
 }
-static inline void pte_free_finish(struct mmu_gather *tlb) { }
 #endif /* !CONFIG_SMP */
 
 static inline void __pte_free_tlb(struct mmu_gather *tlb, struct page *ptepage,
Index: linux-2.6/arch/powerpc/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/powerpc/include/asm/tlb.h
+++ linux-2.6/arch/powerpc/include/asm/tlb.h
@@ -28,16 +28,6 @@
 #define tlb_start_vma(tlb, vma)	do { } while (0)
 #define tlb_end_vma(tlb, vma)	do { } while (0)
 
-#define HAVE_ARCH_MMU_GATHER 1
-
-struct pte_freelist_batch;
-
-struct arch_mmu_gather {
-	struct pte_freelist_batch *batch;
-};
-
-#define ARCH_MMU_GATHER_INIT (struct arch_mmu_gather){ .batch = NULL, }
-
 extern void tlb_flush(struct mmu_gather *tlb);
 
 /* Get the generic bits... */
Index: linux-2.6/arch/powerpc/mm/pgtable.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/pgtable.c
+++ linux-2.6/arch/powerpc/mm/pgtable.c
@@ -33,104 +33,6 @@
 
 #include "mmu_decl.h"
 
-#ifdef CONFIG_SMP
-
-/*
- * Handle batching of page table freeing on SMP. Page tables are
- * queued up and send to be freed later by RCU in order to avoid
- * freeing a page table page that is being walked without locks
- */
-
-static unsigned long pte_freelist_forced_free;
-
-struct pte_freelist_batch
-{
-	struct rcu_head	rcu;
-	unsigned int	index;
-	unsigned long	tables[0];
-};
-
-#define PTE_FREELIST_SIZE \
-	((PAGE_SIZE - sizeof(struct pte_freelist_batch)) \
-	  / sizeof(unsigned long))
-
-static void pte_free_smp_sync(void *arg)
-{
-	/* Do nothing, just ensure we sync with all CPUs */
-}
-
-/* This is only called when we are critically out of memory
- * (and fail to get a page in pte_free_tlb).
- */
-static void pgtable_free_now(void *table, unsigned shift)
-{
-	pte_freelist_forced_free++;
-
-	smp_call_function(pte_free_smp_sync, NULL, 1);
-
-	pgtable_free(table, shift);
-}
-
-static void pte_free_rcu_callback(struct rcu_head *head)
-{
-	struct pte_freelist_batch *batch =
-		container_of(head, struct pte_freelist_batch, rcu);
-	unsigned int i;
-
-	for (i = 0; i < batch->index; i++) {
-		void *table = (void *)(batch->tables[i] & ~MAX_PGTABLE_INDEX_SIZE);
-		unsigned shift = batch->tables[i] & MAX_PGTABLE_INDEX_SIZE;
-
-		pgtable_free(table, shift);
-	}
-
-	free_page((unsigned long)batch);
-}
-
-static void pte_free_submit(struct pte_freelist_batch *batch)
-{
-	call_rcu_sched(&batch->rcu, pte_free_rcu_callback);
-}
-
-void pgtable_free_tlb(struct mmu_gather *tlb, void *table, unsigned shift)
-{
-	struct pte_freelist_batch **batchp = &tlb->arch.batch;
-	unsigned long pgf;
-
-	if (atomic_read(&tlb->mm->mm_users) < 2) {
-		pgtable_free(table, shift);
-		return;
-	}
-
-	if (*batchp == NULL) {
-		*batchp = (struct pte_freelist_batch *)__get_free_page(GFP_ATOMIC);
-		if (*batchp == NULL) {
-			pgtable_free_now(table, shift);
-			return;
-		}
-		(*batchp)->index = 0;
-	}
-	BUG_ON(shift > MAX_PGTABLE_INDEX_SIZE);
-	pgf = (unsigned long)table | shift;
-	(*batchp)->tables[(*batchp)->index++] = pgf;
-	if ((*batchp)->index == PTE_FREELIST_SIZE) {
-		pte_free_submit(*batchp);
-		*batchp = NULL;
-	}
-}
-
-void pte_free_finish(struct mmu_gather *tlb)
-{
-	struct pte_freelist_batch **batchp = &tlb->arch.batch;
-
-	if (*batchp == NULL)
-		return;
-	pte_free_submit(*batchp);
-	*batchp = NULL;
-}
-
-#endif /* CONFIG_SMP */
-
 static inline int is_exec_fault(void)
 {
 	return current->thread.regs && TRAP(current->thread.regs) == 0x400;
Index: linux-2.6/arch/powerpc/mm/tlb_hash32.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_hash32.c
+++ linux-2.6/arch/powerpc/mm/tlb_hash32.c
@@ -71,9 +71,6 @@ void tlb_flush(struct mmu_gather *tlb)
 		 */
 		_tlbia();
 	}
-
-	/* Push out batch of freed page tables */
-	pte_free_finish(tlb);
 }
 
 /*
Index: linux-2.6/arch/powerpc/mm/tlb_hash64.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_hash64.c
+++ linux-2.6/arch/powerpc/mm/tlb_hash64.c
@@ -165,9 +165,6 @@ void tlb_flush(struct mmu_gather *tlb)
 		__flush_tlb_pending(tlbbatch);
 
 	put_cpu_var(ppc64_tlb_batch);
-
-	/* Push out batch of freed page tables */
-	pte_free_finish(tlb);
 }
 
 /**
Index: linux-2.6/arch/powerpc/mm/tlb_nohash.c
===================================================================
--- linux-2.6.orig/arch/powerpc/mm/tlb_nohash.c
+++ linux-2.6/arch/powerpc/mm/tlb_nohash.c
@@ -299,9 +299,6 @@ EXPORT_SYMBOL(flush_tlb_range);
 void tlb_flush(struct mmu_gather *tlb)
 {
 	flush_tlb_mm(tlb->mm);
-
-	/* Push out batch of freed page tables */
-	pte_free_finish(tlb);
 }
 
 /*
Index: linux-2.6/include/asm-generic/tlb.h
===================================================================
--- linux-2.6.orig/include/asm-generic/tlb.h
+++ linux-2.6/include/asm-generic/tlb.h
@@ -27,6 +27,49 @@
   #define tlb_fast_mode(tlb) 1
 #endif
 
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+/*
+ * Semi RCU freeing of the page directories.
+ *
+ * This is needed by some architectures to implement software pagetable walkers.
+ *
+ * gup_fast() and other software pagetable walkers do a lockless page-table
+ * walk and therefore needs some synchronization with the freeing of the page
+ * directories. The chosen means to accomplish that is by disabling IRQs over
+ * the walk.
+ *
+ * Architectures that use IPIs to flush TLBs will then automagically DTRT,
+ * since we unlink the page, flush TLBs, free the page. Since the disabling of
+ * IRQs delays the completion of the TLB flush we can never observe an already
+ * freed page.
+ *
+ * Architectures that do not have this (PPC) need to delay the freeing by some
+ * other means, this is that means.
+ *
+ * What we do is batch the freed directory pages (tables) and RCU free them.
+ * We use the sched RCU variant, as that guarantees that IRQ/preempt disabling
+ * holds off grace periods.
+ *
+ * However, in order to batch these pages we need to allocate storage, this
+ * allocation is deep inside the MM code and can thus easily fail on memory
+ * pressure. To guarantee progress we fall back to single table freeing, see
+ * the implementation of tlb_remove_table_one().
+ *
+ */
+struct mmu_table_batch {
+	struct rcu_head		rcu;
+	unsigned int		nr;
+	void			*tables[0];
+};
+
+#define MAX_TABLE_BATCH		\
+	((PAGE_SIZE - sizeof(struct mmu_table_batch)) / sizeof(void *))
+
+extern void tlb_table_flush(struct mmu_gather *tlb);
+extern void tlb_remove_table(struct mmu_gather *tlb, void *table);
+
+#endif
+
 /* struct mmu_gather is an opaque type used by the mm code for passing around
  * any data needed by arch specific code for tlb_remove_page.
  */
@@ -36,11 +79,12 @@ struct mmu_gather {
 	unsigned int		max;	/* nr < max */
 	unsigned int		need_flush;/* Really unmapped some ptes? */
 	unsigned int		fullmm; /* non-zero means full mm flush */
-#ifdef HAVE_ARCH_MMU_GATHER
-	struct arch_mmu_gather	arch;
-#endif
 	struct page		**pages;
 	struct page		*local[8];
+
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+	struct mmu_table_batch	*batch;
+#endif
 };
 
 static inline void __tlb_alloc_page(struct mmu_gather *tlb)
@@ -72,8 +116,8 @@ tlb_gather_mmu(struct mmu_gather *tlb, s
 
 	tlb->fullmm = full_mm_flush;
 
-#ifdef HAVE_ARCH_MMU_GATHER
-	tlb->arch = ARCH_MMU_GATHER_INIT;
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+	tlb->batch = NULL;
 #endif
 }
 
@@ -84,6 +128,9 @@ tlb_flush_mmu(struct mmu_gather *tlb, un
 		return;
 	tlb->need_flush = 0;
 	tlb_flush(tlb);
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+	tlb_table_flush(tlb);
+#endif
 	if (!tlb_fast_mode(tlb)) {
 		free_pages_and_swap_cache(tlb->pages, tlb->nr);
 		tlb->nr = 0;
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -193,6 +193,83 @@ static void check_sync_rss_stat(struct t
 
 #endif
 
+#ifdef CONFIG_HAVE_RCU_TABLE_FREE
+
+/*
+ * See the comment near struct mmu_table_batch.
+ */
+
+static void tlb_remove_table_smp_sync(void *arg)
+{
+	/* Simply deliver the interrupt */
+}
+
+static void tlb_remove_table_one(void *table)
+{
+	/*
+	 * This isn't an RCU grace period and hence the page-tables cannot be
+	 * assumed to be actually RCU-freed.
+	 *
+	 * It is however sufficient for software page-table walkers that rely on
+	 * IRQ disabling. See the comment near struct mmu_table_batch.
+	 */
+	smp_call_function(tlb_remove_table_smp_sync, NULL, 1);
+	__tlb_remove_table(table);
+}
+
+static void tlb_remove_table_rcu(struct rcu_head *head)
+{
+	struct mmu_table_batch *batch;
+	int i;
+
+	batch = container_of(head, struct mmu_table_batch, rcu);
+
+	for (i = 0; i < batch->nr; i++)
+		__tlb_remove_table(batch->tables[i]);
+
+	free_page((unsigned long)batch);
+}
+
+void tlb_table_flush(struct mmu_gather *tlb)
+{
+	struct mmu_table_batch **batch = &tlb->batch;
+
+	if (*batch) {
+		call_rcu_sched(&(*batch)->rcu, tlb_remove_table_rcu);
+		*batch = NULL;
+	}
+}
+
+void tlb_remove_table(struct mmu_gather *tlb, void *table)
+{
+	struct mmu_table_batch **batch = &tlb->batch;
+
+	tlb->need_flush = 1;
+
+	/*
+	 * When there's less then two users of this mm there cannot be a
+	 * concurrent page-table walk.
+	 */
+	if (atomic_read(&tlb->mm->mm_users) < 2) {
+		__tlb_remove_table(table);
+		return;
+	}
+
+	if (*batch == NULL) {
+		*batch = (struct mmu_table_batch *)__get_free_page(GFP_NOWAIT | __GFP_NOWARN);
+		if (*batch == NULL) {
+			tlb_remove_table_one(table);
+			return;
+		}
+		(*batch)->nr = 0;
+	}
+	(*batch)->tables[(*batch)->nr++] = table;
+	if ((*batch)->nr == MAX_TABLE_BATCH)
+		tlb_table_flush(tlb);
+}
+
+#endif
+
 /*
  * If a p?d_bad entry is found while walking page tables, report
  * the error, before resetting entry to p?d_none.  Usually (but
Index: linux-2.6/arch/Kconfig
===================================================================
--- linux-2.6.orig/arch/Kconfig
+++ linux-2.6/arch/Kconfig
@@ -178,4 +178,7 @@ config HAVE_ARCH_JUMP_LABEL
 config HAVE_ARCH_MUTEX_CPU_RELAX
 	bool
 
+config HAVE_RCU_TABLE_FREE
+	bool
+
 source "kernel/gcov/Kconfig"
Index: linux-2.6/arch/powerpc/Kconfig
===================================================================
--- linux-2.6.orig/arch/powerpc/Kconfig
+++ linux-2.6/arch/powerpc/Kconfig
@@ -134,6 +134,7 @@ config PPC
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_SPARSE_IRQ
 	select IRQ_PER_CPU
+	select HAVE_RCU_TABLE_FREE if SMP
 
 config EARLY_PRINTK
 	bool


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[PATCH 12/25] lockdep, mutex: Provide mutex_lock_nest_lock

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-lockdep_mutex-provide_mutex_lock_nest_lock.patch --]
[-- Type: text/plain, Size: 5738 bytes --]

Provide the mutex_lock_nest_lock() annotation.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/lockdep.h |    3 +++
 include/linux/mutex.h   |    9 +++++++++
 kernel/mutex.c          |   25 +++++++++++++++++--------
 3 files changed, 29 insertions(+), 8 deletions(-)

Index: linux-2.6/include/linux/lockdep.h
===================================================================
--- linux-2.6.orig/include/linux/lockdep.h
+++ linux-2.6/include/linux/lockdep.h
@@ -495,12 +495,15 @@ static inline void print_irqtrace_events
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 # ifdef CONFIG_PROVE_LOCKING
 #  define mutex_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 2, NULL, i)
+#  define mutex_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 2, n, i)
 # else
 #  define mutex_acquire(l, s, t, i)		lock_acquire(l, s, t, 0, 1, NULL, i)
+#  define mutex_acquire_nest(l, s, t, n, i)	lock_acquire(l, s, t, 0, 1, n, i)
 # endif
 # define mutex_release(l, n, i)			lock_release(l, n, i)
 #else
 # define mutex_acquire(l, s, t, i)		do { } while (0)
+# define mutex_acquire_nest(l, s, t, n, i)	do { } while (0)
 # define mutex_release(l, n, i)			do { } while (0)
 #endif
 
Index: linux-2.6/include/linux/mutex.h
===================================================================
--- linux-2.6.orig/include/linux/mutex.h
+++ linux-2.6/include/linux/mutex.h
@@ -132,6 +132,7 @@ static inline int mutex_is_locked(struct
  */
 #ifdef CONFIG_DEBUG_LOCK_ALLOC
 extern void mutex_lock_nested(struct mutex *lock, unsigned int subclass);
+extern void _mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest_lock);
 extern int __must_check mutex_lock_interruptible_nested(struct mutex *lock,
 					unsigned int subclass);
 extern int __must_check mutex_lock_killable_nested(struct mutex *lock,
@@ -140,6 +141,13 @@ extern int __must_check mutex_lock_killa
 #define mutex_lock(lock) mutex_lock_nested(lock, 0)
 #define mutex_lock_interruptible(lock) mutex_lock_interruptible_nested(lock, 0)
 #define mutex_lock_killable(lock) mutex_lock_killable_nested(lock, 0)
+
+#define mutex_lock_nest_lock(lock, nest_lock)				\
+do {									\
+	typecheck(struct lockdep_map *, &(nest_lock)->dep_map);		\
+	_mutex_lock_nest_lock(lock, &(nest_lock)->dep_map);		\
+} while (0)
+
 #else
 extern void mutex_lock(struct mutex *lock);
 extern int __must_check mutex_lock_interruptible(struct mutex *lock);
@@ -148,6 +156,7 @@ extern int __must_check mutex_lock_killa
 # define mutex_lock_nested(lock, subclass) mutex_lock(lock)
 # define mutex_lock_interruptible_nested(lock, subclass) mutex_lock_interruptible(lock)
 # define mutex_lock_killable_nested(lock, subclass) mutex_lock_killable(lock)
+# define mutex_lock_nest_lock(lock, nest_lock) mutex_lock(lock)
 #endif
 
 /*
Index: linux-2.6/kernel/mutex.c
===================================================================
--- linux-2.6.orig/kernel/mutex.c
+++ linux-2.6/kernel/mutex.c
@@ -131,14 +131,14 @@ EXPORT_SYMBOL(mutex_unlock);
  */
 static inline int __sched
 __mutex_lock_common(struct mutex *lock, long state, unsigned int subclass,
-	       	unsigned long ip)
+		    struct lockdep_map *nest_lock, unsigned long ip)
 {
 	struct task_struct *task = current;
 	struct mutex_waiter waiter;
 	unsigned long flags;
 
 	preempt_disable();
-	mutex_acquire(&lock->dep_map, subclass, 0, ip);
+	mutex_acquire_nest(&lock->dep_map, subclass, 0, nest_lock, ip);
 
 #ifdef CONFIG_MUTEX_SPIN_ON_OWNER
 	/*
@@ -276,16 +276,25 @@ void __sched
 mutex_lock_nested(struct mutex *lock, unsigned int subclass)
 {
 	might_sleep();
-	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, _RET_IP_);
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, subclass, NULL, _RET_IP_);
 }
 
 EXPORT_SYMBOL_GPL(mutex_lock_nested);
 
+void __sched
+_mutex_lock_nest_lock(struct mutex *lock, struct lockdep_map *nest)
+{
+	might_sleep();
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, nest, _RET_IP_);
+}
+
+EXPORT_SYMBOL_GPL(_mutex_lock_nest_lock);
+
 int __sched
 mutex_lock_killable_nested(struct mutex *lock, unsigned int subclass)
 {
 	might_sleep();
-	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, _RET_IP_);
+	return __mutex_lock_common(lock, TASK_KILLABLE, subclass, NULL, _RET_IP_);
 }
 EXPORT_SYMBOL_GPL(mutex_lock_killable_nested);
 
@@ -294,7 +303,7 @@ mutex_lock_interruptible_nested(struct m
 {
 	might_sleep();
 	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE,
-				   subclass, _RET_IP_);
+				   subclass, NULL, _RET_IP_);
 }
 
 EXPORT_SYMBOL_GPL(mutex_lock_interruptible_nested);
@@ -400,7 +409,7 @@ __mutex_lock_slowpath(atomic_t *lock_cou
 {
 	struct mutex *lock = container_of(lock_count, struct mutex, count);
 
-	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, _RET_IP_);
+	__mutex_lock_common(lock, TASK_UNINTERRUPTIBLE, 0, NULL, _RET_IP_);
 }
 
 static noinline int __sched
@@ -408,7 +417,7 @@ __mutex_lock_killable_slowpath(atomic_t 
 {
 	struct mutex *lock = container_of(lock_count, struct mutex, count);
 
-	return __mutex_lock_common(lock, TASK_KILLABLE, 0, _RET_IP_);
+	return __mutex_lock_common(lock, TASK_KILLABLE, 0, NULL, _RET_IP_);
 }
 
 static noinline int __sched
@@ -416,7 +425,7 @@ __mutex_lock_interruptible_slowpath(atom
 {
 	struct mutex *lock = container_of(lock_count, struct mutex, count);
 
-	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, _RET_IP_);
+	return __mutex_lock_common(lock, TASK_INTERRUPTIBLE, 0, NULL, _RET_IP_);
 }
 #endif
 


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[PATCH 13/25] mutex: Provide mutex_is_contended

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mutex-provide_mutex_is_contended.patch --]
[-- Type: text/plain, Size: 1037 bytes --]

Usable for lock-breaks and such.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/mutex.h |    5 +++++
 1 file changed, 5 insertions(+)

Index: linux-2.6/include/linux/mutex.h
===================================================================
--- linux-2.6.orig/include/linux/mutex.h
+++ linux-2.6/include/linux/mutex.h
@@ -126,6 +126,11 @@ static inline int mutex_is_locked(struct
 	return atomic_read(&lock->count) != 1;
 }
 
+static inline int mutex_is_contended(struct mutex *lock)
+{
+	return atomic_read(&lock->count) < 0;
+}
+
 /*
  * See kernel/mutex.c for detailed documentation of these APIs.
  * Also see Documentation/mutex-design.txt.


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[PATCH 14/25] mm: Convert i_mmap_lock to a mutex

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-convert_i_mmap_lock_to_mutexes.patch --]
[-- Type: text/plain, Size: 26454 bytes --]

Straight fwd conversion of i_mmap_lock to a mutex

Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 Documentation/lockstat.txt   |    2 +-
 Documentation/vm/locking     |    2 +-
 arch/x86/mm/hugetlbpage.c    |    4 ++--
 fs/gfs2/main.c               |    2 +-
 fs/hugetlbfs/inode.c         |    4 ++--
 fs/inode.c                   |    2 +-
 fs/nilfs2/page.c             |    2 +-
 include/linux/fs.h           |    2 +-
 include/linux/mm.h           |    2 +-
 include/linux/mmu_notifier.h |    2 +-
 kernel/fork.c                |    4 ++--
 mm/filemap.c                 |   10 +++++-----
 mm/filemap_xip.c             |    4 ++--
 mm/fremap.c                  |    4 ++--
 mm/hugetlb.c                 |   14 +++++++-------
 mm/memory-failure.c          |    4 ++--
 mm/memory.c                  |   22 +++++++++++-----------
 mm/mmap.c                    |   22 +++++++++++-----------
 mm/mremap.c                  |    4 ++--
 mm/rmap.c                    |   28 ++++++++++++++--------------
 20 files changed, 70 insertions(+), 70 deletions(-)

Index: linux-2.6/arch/x86/mm/hugetlbpage.c
===================================================================
--- linux-2.6.orig/arch/x86/mm/hugetlbpage.c
+++ linux-2.6/arch/x86/mm/hugetlbpage.c
@@ -72,7 +72,7 @@ static void huge_pmd_share(struct mm_str
 	if (!vma_shareable(vma, addr))
 		return;
 
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
 		if (svma == vma)
 			continue;
@@ -97,7 +97,7 @@ static void huge_pmd_share(struct mm_str
 		put_page(virt_to_page(spte));
 	spin_unlock(&mm->page_table_lock);
 out:
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 }
 
 /*
Index: linux-2.6/fs/hugetlbfs/inode.c
===================================================================
--- linux-2.6.orig/fs/hugetlbfs/inode.c
+++ linux-2.6/fs/hugetlbfs/inode.c
@@ -413,10 +413,10 @@ static int hugetlb_vmtruncate(struct ino
 	pgoff = offset >> PAGE_SHIFT;
 
 	i_size_write(inode, offset);
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	if (!prio_tree_empty(&mapping->i_mmap))
 		hugetlb_vmtruncate_list(&mapping->i_mmap, pgoff);
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	truncate_hugepages(inode, offset);
 	return 0;
 }
Index: linux-2.6/fs/inode.c
===================================================================
--- linux-2.6.orig/fs/inode.c
+++ linux-2.6/fs/inode.c
@@ -310,7 +310,7 @@ void inode_init_once(struct inode *inode
 	INIT_LIST_HEAD(&inode->i_lru);
 	INIT_RADIX_TREE(&inode->i_data.page_tree, GFP_ATOMIC);
 	spin_lock_init(&inode->i_data.tree_lock);
-	spin_lock_init(&inode->i_data.i_mmap_lock);
+	mutex_init(&inode->i_data.i_mmap_mutex);
 	INIT_LIST_HEAD(&inode->i_data.private_list);
 	spin_lock_init(&inode->i_data.private_lock);
 	INIT_RAW_PRIO_TREE_ROOT(&inode->i_data.i_mmap);
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -639,7 +639,7 @@ struct address_space {
 	unsigned int		i_mmap_writable;/* count VM_SHARED mappings */
 	struct prio_tree_root	i_mmap;		/* tree of private and shared mappings */
 	struct list_head	i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
-	spinlock_t		i_mmap_lock;	/* protect tree, count, list */
+	struct mutex		i_mmap_mutex;	/* protect tree, count, list */
 	unsigned int		truncate_count;	/* Cover race condition with truncate */
 	unsigned long		nrpages;	/* number of total pages */
 	pgoff_t			writeback_index;/* writeback starts here */
Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -876,7 +876,7 @@ struct zap_details {
 	struct address_space *check_mapping;	/* Check page->mapping if set */
 	pgoff_t	first_index;			/* Lowest page->index to unmap */
 	pgoff_t last_index;			/* Highest page->index to unmap */
-	spinlock_t *i_mmap_lock;		/* For unmap_mapping_range: */
+	struct mutex *i_mmap_mutex;		/* For unmap_mapping_range: */
 	unsigned long truncate_count;		/* Compare vm_truncate_count */
 };
 
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c
+++ linux-2.6/kernel/fork.c
@@ -376,7 +376,7 @@ static int dup_mmap(struct mm_struct *mm
 			get_file(file);
 			if (tmp->vm_flags & VM_DENYWRITE)
 				atomic_dec(&inode->i_writecount);
-			spin_lock(&mapping->i_mmap_lock);
+			mutex_lock(&mapping->i_mmap_mutex);
 			if (tmp->vm_flags & VM_SHARED)
 				mapping->i_mmap_writable++;
 			tmp->vm_truncate_count = mpnt->vm_truncate_count;
@@ -384,7 +384,7 @@ static int dup_mmap(struct mm_struct *mm
 			/* insert tmp into the share list, just after mpnt */
 			vma_prio_tree_add(tmp, mpnt);
 			flush_dcache_mmap_unlock(mapping);
-			spin_unlock(&mapping->i_mmap_lock);
+			mutex_unlock(&mapping->i_mmap_mutex);
 		}
 
 		/*
Index: linux-2.6/mm/filemap_xip.c
===================================================================
--- linux-2.6.orig/mm/filemap_xip.c
+++ linux-2.6/mm/filemap_xip.c
@@ -183,7 +183,7 @@ __xip_unmap (struct address_space * mapp
 		return;
 
 retry:
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		mm = vma->vm_mm;
 		address = vma->vm_start +
@@ -201,7 +201,7 @@ __xip_unmap (struct address_space * mapp
 			page_cache_release(page);
 		}
 	}
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 
 	if (locked) {
 		mutex_unlock(&xip_sparse_mutex);
Index: linux-2.6/mm/fremap.c
===================================================================
--- linux-2.6.orig/mm/fremap.c
+++ linux-2.6/mm/fremap.c
@@ -211,13 +211,13 @@ SYSCALL_DEFINE5(remap_file_pages, unsign
 			}
 			goto out;
 		}
-		spin_lock(&mapping->i_mmap_lock);
+		mutex_lock(&mapping->i_mmap_mutex);
 		flush_dcache_mmap_lock(mapping);
 		vma->vm_flags |= VM_NONLINEAR;
 		vma_prio_tree_remove(vma, &mapping->i_mmap);
 		vma_nonlinear_insert(vma, &mapping->i_mmap_nonlinear);
 		flush_dcache_mmap_unlock(mapping);
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 	}
 
 	if (vma->vm_flags & VM_LOCKED) {
Index: linux-2.6/mm/hugetlb.c
===================================================================
--- linux-2.6.orig/mm/hugetlb.c
+++ linux-2.6/mm/hugetlb.c
@@ -2207,7 +2207,7 @@ void __unmap_hugepage_range(struct vm_ar
 	unsigned long sz = huge_page_size(h);
 
 	/*
-	 * A page gathering list, protected by per file i_mmap_lock. The
+	 * A page gathering list, protected by per file i_mmap_mutex. The
 	 * lock is used to avoid list corruption from multiple unmapping
 	 * of the same page since we are using page->lru.
 	 */
@@ -2276,9 +2276,9 @@ void __unmap_hugepage_range(struct vm_ar
 void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
 			  unsigned long end, struct page *ref_page)
 {
-	spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
+	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
 	__unmap_hugepage_range(vma, start, end, ref_page);
-	spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
+	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
 }
 
 /*
@@ -2310,7 +2310,7 @@ static int unmap_ref_private(struct mm_s
 	 * this mapping should be shared between all the VMAs,
 	 * __unmap_hugepage_range() is called as the lock is already held
 	 */
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(iter_vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		/* Do not unmap the current VMA */
 		if (iter_vma == vma)
@@ -2328,7 +2328,7 @@ static int unmap_ref_private(struct mm_s
 				address, address + huge_page_size(h),
 				page);
 	}
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 
 	return 1;
 }
@@ -2812,7 +2812,7 @@ void hugetlb_change_protection(struct vm
 	BUG_ON(address >= end);
 	flush_cache_range(vma, address, end);
 
-	spin_lock(&vma->vm_file->f_mapping->i_mmap_lock);
+	mutex_lock(&vma->vm_file->f_mapping->i_mmap_mutex);
 	spin_lock(&mm->page_table_lock);
 	for (; address < end; address += huge_page_size(h)) {
 		ptep = huge_pte_offset(mm, address);
@@ -2827,7 +2827,7 @@ void hugetlb_change_protection(struct vm
 		}
 	}
 	spin_unlock(&mm->page_table_lock);
-	spin_unlock(&vma->vm_file->f_mapping->i_mmap_lock);
+	mutex_unlock(&vma->vm_file->f_mapping->i_mmap_mutex);
 
 	flush_tlb_range(vma, start, end);
 }
Index: linux-2.6/mm/memory-failure.c
===================================================================
--- linux-2.6.orig/mm/memory-failure.c
+++ linux-2.6/mm/memory-failure.c
@@ -431,7 +431,7 @@ static void collect_procs_file(struct pa
 	 */
 
 	read_lock(&tasklist_lock);
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	for_each_process(tsk) {
 		pgoff_t pgoff = page->index << (PAGE_CACHE_SHIFT - PAGE_SHIFT);
 
@@ -451,7 +451,7 @@ static void collect_procs_file(struct pa
 				add_to_kill(tsk, page, vma, to_kill, tkc);
 		}
 	}
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	read_unlock(&tasklist_lock);
 }
 
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -1205,7 +1205,7 @@ unsigned long unmap_vmas(struct mmu_gath
 {
 	long zap_work = ZAP_BLOCK_SIZE;
 	unsigned long start = start_addr;
-	spinlock_t *i_mmap_lock = details? details->i_mmap_lock: NULL;
+	struct mutex *i_mmap_mutex = details ? details->i_mmap_mutex : NULL;
 	struct mm_struct *mm = vma->vm_mm;
 
 	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
@@ -1255,8 +1255,8 @@ unsigned long unmap_vmas(struct mmu_gath
 			}
 
 			if (need_resched() ||
-				(i_mmap_lock && spin_needbreak(i_mmap_lock))) {
-				if (i_mmap_lock)
+				(i_mmap_mutex && mutex_is_contended(i_mmap_mutex))) {
+				if (i_mmap_mutex)
 					goto out;
 				cond_resched();
 			}
@@ -2531,7 +2531,7 @@ static int do_wp_page(struct mm_struct *
 /*
  * Helper functions for unmap_mapping_range().
  *
- * __ Notes on dropping i_mmap_lock to reduce latency while unmapping __
+ * __ Notes on dropping i_mmap_mutex to reduce latency while unmapping __
  *
  * We have to restart searching the prio_tree whenever we drop the lock,
  * since the iterator is only valid while the lock is held, and anyway
@@ -2550,7 +2550,7 @@ static int do_wp_page(struct mm_struct *
  * can't efficiently keep all vmas in step with mapping->truncate_count:
  * so instead reset them all whenever it wraps back to 0 (then go to 1).
  * mapping->truncate_count and vma->vm_truncate_count are protected by
- * i_mmap_lock.
+ * i_mmap_mutex.
  *
  * In order to make forward progress despite repeatedly restarting some
  * large vma, note the restart_addr from unmap_vmas when it breaks out:
@@ -2600,7 +2600,7 @@ static int unmap_mapping_range_vma(struc
 
 	restart_addr = zap_page_range(vma, start_addr,
 					end_addr - start_addr, details);
-	need_break = need_resched() || spin_needbreak(details->i_mmap_lock);
+	need_break = need_resched() || mutex_is_contended(details->i_mmap_mutex);
 
 	if (restart_addr >= end_addr) {
 		/* We have now completed this vma: mark it so */
@@ -2614,9 +2614,9 @@ static int unmap_mapping_range_vma(struc
 			goto again;
 	}
 
-	spin_unlock(details->i_mmap_lock);
+	mutex_unlock(details->i_mmap_mutex);
 	cond_resched();
-	spin_lock(details->i_mmap_lock);
+	mutex_lock(details->i_mmap_mutex);
 	return -EINTR;
 }
 
@@ -2710,9 +2710,9 @@ void unmap_mapping_range(struct address_
 	details.last_index = hba + hlen - 1;
 	if (details.last_index < details.first_index)
 		details.last_index = ULONG_MAX;
-	details.i_mmap_lock = &mapping->i_mmap_lock;
+	details.i_mmap_mutex = &mapping->i_mmap_mutex;
 
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 
 	/* Protect against endless unmapping loops */
 	mapping->truncate_count++;
@@ -2727,7 +2727,7 @@ void unmap_mapping_range(struct address_
 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
 	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
 		unmap_mapping_range_list(&mapping->i_mmap_nonlinear, &details);
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 }
 EXPORT_SYMBOL(unmap_mapping_range);
 
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c
+++ linux-2.6/mm/mmap.c
@@ -190,7 +190,7 @@ int __vm_enough_memory(struct mm_struct 
 }
 
 /*
- * Requires inode->i_mapping->i_mmap_lock
+ * Requires inode->i_mapping->i_mmap_mutex
  */
 static void __remove_shared_vm_struct(struct vm_area_struct *vma,
 		struct file *file, struct address_space *mapping)
@@ -218,9 +218,9 @@ void unlink_file_vma(struct vm_area_stru
 
 	if (file) {
 		struct address_space *mapping = file->f_mapping;
-		spin_lock(&mapping->i_mmap_lock);
+		mutex_lock(&mapping->i_mmap_mutex);
 		__remove_shared_vm_struct(vma, file, mapping);
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 	}
 }
 
@@ -465,7 +465,7 @@ static void vma_link(struct mm_struct *m
 		mapping = vma->vm_file->f_mapping;
 
 	if (mapping) {
-		spin_lock(&mapping->i_mmap_lock);
+		mutex_lock(&mapping->i_mmap_mutex);
 		vma->vm_truncate_count = mapping->truncate_count;
 	}
 
@@ -473,7 +473,7 @@ static void vma_link(struct mm_struct *m
 	__vma_link_file(vma);
 
 	if (mapping)
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 
 	mm->map_count++;
 	validate_mm(mm);
@@ -576,7 +576,7 @@ again:			remove_next = 1 + (end > next->
 		mapping = file->f_mapping;
 		if (!(vma->vm_flags & VM_NONLINEAR))
 			root = &mapping->i_mmap;
-		spin_lock(&mapping->i_mmap_lock);
+		mutex_lock(&mapping->i_mmap_mutex);
 		if (importer &&
 		    vma->vm_truncate_count != next->vm_truncate_count) {
 			/*
@@ -652,7 +652,7 @@ again:			remove_next = 1 + (end > next->
 	if (anon_vma)
 		anon_vma_unlock(anon_vma);
 	if (mapping)
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 
 	if (remove_next) {
 		if (file) {
@@ -2311,7 +2311,7 @@ void exit_mmap(struct mm_struct *mm)
 
 /* Insert vm structure into process list sorted by address
  * and into the inode's i_mmap tree.  If vm_file is non-NULL
- * then i_mmap_lock is taken here.
+ * then i_mmap_mutex is taken here.
  */
 int insert_vm_struct(struct mm_struct * mm, struct vm_area_struct * vma)
 {
@@ -2553,7 +2553,7 @@ static void vm_lock_mapping(struct mm_st
 		 */
 		if (test_and_set_bit(AS_MM_ALL_LOCKS, &mapping->flags))
 			BUG();
-		spin_lock_nest_lock(&mapping->i_mmap_lock, &mm->mmap_sem);
+		mutex_lock_nest_lock(&mapping->i_mmap_mutex, &mm->mmap_sem);
 	}
 }
 
@@ -2580,7 +2580,7 @@ static void vm_lock_mapping(struct mm_st
  * vma in this mm is backed by the same anon_vma or address_space.
  *
  * We can take all the locks in random order because the VM code
- * taking i_mmap_lock or anon_vma->lock outside the mmap_sem never
+ * taking i_mmap_mutex or anon_vma->lock outside the mmap_sem never
  * takes more than one of them in a row. Secondly we're protected
  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
  *
@@ -2652,7 +2652,7 @@ static void vm_unlock_mapping(struct add
 		 * AS_MM_ALL_LOCKS can't change to 0 from under us
 		 * because we hold the mm_all_locks_mutex.
 		 */
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 		if (!test_and_clear_bit(AS_MM_ALL_LOCKS,
 					&mapping->flags))
 			BUG();
Index: linux-2.6/mm/mremap.c
===================================================================
--- linux-2.6.orig/mm/mremap.c
+++ linux-2.6/mm/mremap.c
@@ -93,7 +93,7 @@ static void move_ptes(struct vm_area_str
 		 * and we propagate stale pages into the dst afterward.
 		 */
 		mapping = vma->vm_file->f_mapping;
-		spin_lock(&mapping->i_mmap_lock);
+		mutex_lock(&mapping->i_mmap_mutex);
 		if (new_vma->vm_truncate_count &&
 		    new_vma->vm_truncate_count != vma->vm_truncate_count)
 			new_vma->vm_truncate_count = 0;
@@ -125,7 +125,7 @@ static void move_ptes(struct vm_area_str
 	pte_unmap(new_pte - 1);
 	pte_unmap_unlock(old_pte - 1, old_ptl);
 	if (mapping)
-		spin_unlock(&mapping->i_mmap_lock);
+		mutex_unlock(&mapping->i_mmap_mutex);
 	mmu_notifier_invalidate_range_end(vma->vm_mm, old_start, old_end);
 }
 
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -24,7 +24,7 @@
  *   inode->i_alloc_sem (vmtruncate_range)
  *   mm->mmap_sem
  *     page->flags PG_locked (lock_page)
- *       mapping->i_mmap_lock
+ *       mapping->i_mmap_mutex
  *         anon_vma->lock
  *           mm->page_table_lock or pte_lock
  *             zone->lru_lock (in mark_page_accessed, isolate_lru_page)
@@ -625,14 +625,14 @@ static int page_referenced_file(struct p
 	 * The page lock not only makes sure that page->mapping cannot
 	 * suddenly be NULLified by truncation, it makes sure that the
 	 * structure at mapping cannot be freed and reused yet,
-	 * so we can safely take mapping->i_mmap_lock.
+	 * so we can safely take mapping->i_mmap_mutex.
 	 */
 	BUG_ON(!PageLocked(page));
 
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 
 	/*
-	 * i_mmap_lock does not stabilize mapcount at all, but mapcount
+	 * i_mmap_mutex does not stabilize mapcount at all, but mapcount
 	 * is more likely to be accurate if we note it after spinning.
 	 */
 	mapcount = page_mapcount(page);
@@ -654,7 +654,7 @@ static int page_referenced_file(struct p
 			break;
 	}
 
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	return referenced;
 }
 
@@ -741,7 +741,7 @@ static int page_mkclean_file(struct addr
 
 	BUG_ON(PageAnon(page));
 
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		if (vma->vm_flags & VM_SHARED) {
 			unsigned long address = vma_address(page, vma);
@@ -750,7 +750,7 @@ static int page_mkclean_file(struct addr
 			ret += page_mkclean_one(page, vma, address);
 		}
 	}
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	return ret;
 }
 
@@ -1101,7 +1101,7 @@ int try_to_unmap_one(struct page *page, 
 	/*
 	 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
 	 * unstable result and race. Plus, We can't wait here because
-	 * we now hold anon_vma->lock or mapping->i_mmap_lock.
+	 * we now hold anon_vma->lock or mapping->i_mmap_mutex.
 	 * if trylock failed, the page remain in evictable lru and later
 	 * vmscan could retry to move the page to unevictable lru if the
 	 * page is actually mlocked.
@@ -1327,7 +1327,7 @@ static int try_to_unmap_file(struct page
 	unsigned long max_nl_size = 0;
 	unsigned int mapcount;
 
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		unsigned long address = vma_address(page, vma);
 		if (address == -EFAULT)
@@ -1373,7 +1373,7 @@ static int try_to_unmap_file(struct page
 	mapcount = page_mapcount(page);
 	if (!mapcount)
 		goto out;
-	cond_resched_lock(&mapping->i_mmap_lock);
+	cond_resched();
 
 	max_nl_size = (max_nl_size + CLUSTER_SIZE - 1) & CLUSTER_MASK;
 	if (max_nl_cursor == 0)
@@ -1395,7 +1395,7 @@ static int try_to_unmap_file(struct page
 			}
 			vma->vm_private_data = (void *) max_nl_cursor;
 		}
-		cond_resched_lock(&mapping->i_mmap_lock);
+		cond_resched();
 		max_nl_cursor += CLUSTER_SIZE;
 	} while (max_nl_cursor <= max_nl_size);
 
@@ -1407,7 +1407,7 @@ static int try_to_unmap_file(struct page
 	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
 		vma->vm_private_data = NULL;
 out:
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	return ret;
 }
 
@@ -1552,7 +1552,7 @@ static int rmap_walk_file(struct page *p
 
 	if (!mapping)
 		return ret;
-	spin_lock(&mapping->i_mmap_lock);
+	mutex_lock(&mapping->i_mmap_mutex);
 	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, pgoff, pgoff) {
 		unsigned long address = vma_address(page, vma);
 		if (address == -EFAULT)
@@ -1566,7 +1566,7 @@ static int rmap_walk_file(struct page *p
 	 * never contain migration ptes.  Decide what to do about this
 	 * limitation to linear when we need rmap_walk() on nonlinear.
 	 */
-	spin_unlock(&mapping->i_mmap_lock);
+	mutex_unlock(&mapping->i_mmap_mutex);
 	return ret;
 }
 
Index: linux-2.6/fs/gfs2/main.c
===================================================================
--- linux-2.6.orig/fs/gfs2/main.c
+++ linux-2.6/fs/gfs2/main.c
@@ -62,7 +62,7 @@ static void gfs2_init_gl_aspace_once(voi
 	memset(mapping, 0, sizeof(*mapping));
 	INIT_RADIX_TREE(&mapping->page_tree, GFP_ATOMIC);
 	spin_lock_init(&mapping->tree_lock);
-	spin_lock_init(&mapping->i_mmap_lock);
+	mutex_init(&mapping->i_mmap_mutex);
 	INIT_LIST_HEAD(&mapping->private_list);
 	spin_lock_init(&mapping->private_lock);
 	INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
Index: linux-2.6/fs/nilfs2/page.c
===================================================================
--- linux-2.6.orig/fs/nilfs2/page.c
+++ linux-2.6/fs/nilfs2/page.c
@@ -500,7 +500,7 @@ void nilfs_mapping_init_once(struct addr
 	INIT_LIST_HEAD(&mapping->private_list);
 	spin_lock_init(&mapping->private_lock);
 
-	spin_lock_init(&mapping->i_mmap_lock);
+	mutex_init(&mapping->i_mmap_mutex);
 	INIT_RAW_PRIO_TREE_ROOT(&mapping->i_mmap);
 	INIT_LIST_HEAD(&mapping->i_mmap_nonlinear);
 }
Index: linux-2.6/Documentation/lockstat.txt
===================================================================
--- linux-2.6.orig/Documentation/lockstat.txt
+++ linux-2.6/Documentation/lockstat.txt
@@ -136,7 +136,7 @@ The integer part of the time values is i
                              dcache_lock:          1037           1161           0.38          45.32         774.51           6611         243371           0.15         306.48       77387.24
                          &inode->i_mutex:           161            286 18446744073709       62882.54     1244614.55           3653          20598 18446744073709       62318.60     1693822.74
                          &zone->lru_lock:            94             94           0.53           7.33          92.10           4366          32690           0.29          59.81       16350.06
-              &inode->i_data.i_mmap_lock:            79             79           0.40           3.77          53.03          11779          87755           0.28         116.93       29898.44
+              &inode->i_data.i_mmap_mutex:            79             79           0.40           3.77          53.03          11779          87755           0.28         116.93       29898.44
                         &q->__queue_lock:            48             50           0.52          31.62          86.31            774          13131           0.17         113.08       12277.52
                         &rq->rq_lock_key:            43             47           0.74          68.50         170.63           3706          33929           0.22         107.99       17460.62
                       &rq->rq_lock_key#2:            39             46           0.75           6.68          49.03           2979          32292           0.17         125.17       17137.63
Index: linux-2.6/Documentation/vm/locking
===================================================================
--- linux-2.6.orig/Documentation/vm/locking
+++ linux-2.6/Documentation/vm/locking
@@ -66,7 +66,7 @@ in some cases it is not really needed. E
 expand_stack(), it is hard to come up with a destructive scenario without 
 having the vmlist protection in this case.
 
-The page_table_lock nests with the inode i_mmap_lock and the kmem cache
+The page_table_lock nests with the inode i_mmap_mutex and the kmem cache
 c_spinlock spinlocks.  This is okay, since the kmem code asks for pages after
 dropping c_spinlock.  The page_table_lock also nests with pagecache_lock and
 pagemap_lru_lock spinlocks, and no code asks for memory with these locks
Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- linux-2.6.orig/include/linux/mmu_notifier.h
+++ linux-2.6/include/linux/mmu_notifier.h
@@ -150,7 +150,7 @@ struct mmu_notifier_ops {
  * Therefore notifier chains can only be traversed when either
  *
  * 1. mmap_sem is held.
- * 2. One of the reverse map locks is held (i_mmap_lock or anon_vma->lock).
+ * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->lock).
  * 3. No other concurrent thread can access the list (release)
  */
 struct mmu_notifier {
Index: linux-2.6/mm/filemap.c
===================================================================
--- linux-2.6.orig/mm/filemap.c
+++ linux-2.6/mm/filemap.c
@@ -58,16 +58,16 @@
 /*
  * Lock ordering:
  *
- *  ->i_mmap_lock		(truncate_pagecache)
+ *  ->i_mmap_mutex		(truncate_pagecache)
  *    ->private_lock		(__free_pte->__set_page_dirty_buffers)
  *      ->swap_lock		(exclusive_swap_page, others)
  *        ->mapping->tree_lock
  *
  *  ->i_mutex
- *    ->i_mmap_lock		(truncate->unmap_mapping_range)
+ *    ->i_mmap_mutex		(truncate->unmap_mapping_range)
  *
  *  ->mmap_sem
- *    ->i_mmap_lock
+ *    ->i_mmap_mutex
  *      ->page_table_lock or pte_lock	(various, mainly in memory.c)
  *        ->mapping->tree_lock	(arch-dependent flush_dcache_mmap_lock)
  *
@@ -84,7 +84,7 @@
  *    ->sb_lock			(fs/fs-writeback.c)
  *    ->mapping->tree_lock	(__sync_single_inode)
  *
- *  ->i_mmap_lock
+ *  ->i_mmap_mutex
  *    ->anon_vma.lock		(vma_adjust)
  *
  *  ->anon_vma.lock
@@ -104,7 +104,7 @@
  *
  *  (code doesn't rely on that order, so you could switch it around)
  *  ->tasklist_lock             (memory_failure, collect_procs_ao)
- *    ->i_mmap_lock
+ *    ->i_mmap_mutex
  */
 
 /*


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[PATCH 15/25] mm: Extended batches for generic mmu_gather

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-extended_batches_for_generic_mmu_gather.patch --]
[-- Type: text/plain, Size: 5854 bytes --]

Instead of using a single batch (the small on-stack, or an allocated
page), try and extend the batch every time it runs out and only flush
once either the extend fails or we're done.

Requested-by: Nick Piggin <npiggin@suse.de>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/asm-generic/tlb.h |  122 ++++++++++++++++++++++++++++++----------------
 1 file changed, 82 insertions(+), 40 deletions(-)

Index: linux-2.6/include/asm-generic/tlb.h
===================================================================
--- linux-2.6.orig/include/asm-generic/tlb.h
+++ linux-2.6/include/asm-generic/tlb.h
@@ -17,16 +17,6 @@
 #include <asm/pgalloc.h>
 #include <asm/tlbflush.h>
 
-/*
- * For UP we don't need to worry about TLB flush
- * and page free order so much..
- */
-#ifdef CONFIG_SMP
-  #define tlb_fast_mode(tlb) ((tlb)->nr == ~0U)
-#else
-  #define tlb_fast_mode(tlb) 1
-#endif
-
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 /*
  * Semi RCU freeing of the page directories.
@@ -70,31 +60,66 @@ extern void tlb_remove_table(struct mmu_
 
 #endif
 
+struct mmu_gather_batch {
+	struct mmu_gather_batch	*next;
+	unsigned int		nr;
+	unsigned int		max;
+	struct page		*pages[0];
+};
+
+#define MAX_GATHER_BATCH	\
+	((PAGE_SIZE - sizeof(struct mmu_gather_batch)) / sizeof(void *))
+
 /* struct mmu_gather is an opaque type used by the mm code for passing around
  * any data needed by arch specific code for tlb_remove_page.
  */
 struct mmu_gather {
 	struct mm_struct	*mm;
-	unsigned int		nr;	/* set to ~0U means fast mode */
-	unsigned int		max;	/* nr < max */
-	unsigned int		need_flush;/* Really unmapped some ptes? */
-	unsigned int		fullmm; /* non-zero means full mm flush */
-	struct page		**pages;
-	struct page		*local[8];
+	unsigned int		need_flush : 1,	/* Did free PTEs */
+				fast_mode  : 1; /* No batching   */
+	unsigned int		fullmm;		/* Flush full mm */
+
+	struct mmu_gather_batch *active;
+	struct mmu_gather_batch	local;
+	struct page		*__pages[8];
 
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 	struct mmu_table_batch	*batch;
 #endif
 };
 
-static inline void __tlb_alloc_page(struct mmu_gather *tlb)
+/*
+ * For UP we don't need to worry about TLB flush
+ * and page free order so much..
+ */
+#ifdef CONFIG_SMP
+  #define tlb_fast_mode(tlb) (tlb->fast_mode)
+#else
+  #define tlb_fast_mode(tlb) 1
+#endif
+
+static inline int tlb_next_batch(struct mmu_gather *tlb)
 {
-	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+	struct mmu_gather_batch *batch;
 
-	if (addr) {
-		tlb->pages = (void *)addr;
-		tlb->max = PAGE_SIZE / sizeof(struct page *);
+	batch = tlb->active;
+	if (batch->next) {
+		tlb->active = batch->next;
+		return 1;
 	}
+
+	batch = (void *)__get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
+	if (!batch)
+		return 0;
+
+	batch->next = NULL;
+	batch->nr   = 0;
+	batch->max  = MAX_GATHER_BATCH;
+
+	tlb->active->next = batch;
+	tlb->active = batch;
+
+	return 1;
 }
 
 /* tlb_gather_mmu
@@ -105,17 +130,16 @@ tlb_gather_mmu(struct mmu_gather *tlb, s
 {
 	tlb->mm = mm;
 
-	tlb->max = ARRAY_SIZE(tlb->local);
-	tlb->pages = tlb->local;
-
-	if (num_online_cpus() > 1) {
-		tlb->nr = 0;
-		__tlb_alloc_page(tlb);
-	} else /* Use fast mode if only one CPU is online */
-		tlb->nr = ~0U;
-
+	tlb->need_flush = 0;
+	if (num_online_cpus() == 1)
+		tlb->fast_mode = 1;
 	tlb->fullmm = full_mm_flush;
 
+	tlb->local.next = NULL;
+	tlb->local.nr   = 0;
+	tlb->local.max  = ARRAY_SIZE(tlb->__pages);
+	tlb->active     = &tlb->local;
+
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 	tlb->batch = NULL;
 #endif
@@ -124,6 +148,8 @@ tlb_gather_mmu(struct mmu_gather *tlb, s
 static inline void
 tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
+	struct mmu_gather_batch *batch;
+
 	if (!tlb->need_flush)
 		return;
 	tlb->need_flush = 0;
@@ -131,12 +157,14 @@ tlb_flush_mmu(struct mmu_gather *tlb, un
 #ifdef CONFIG_HAVE_RCU_TABLE_FREE
 	tlb_table_flush(tlb);
 #endif
-	if (!tlb_fast_mode(tlb)) {
-		free_pages_and_swap_cache(tlb->pages, tlb->nr);
-		tlb->nr = 0;
-		if (tlb->pages == tlb->local)
-			__tlb_alloc_page(tlb);
+	if (tlb_fast_mode(tlb))
+		return;
+
+	for (batch = &tlb->local; batch; batch = batch->next) {
+		free_pages_and_swap_cache(batch->pages, batch->nr);
+		batch->nr = 0;
 	}
+	tlb->active = &tlb->local;
 }
 
 /* tlb_finish_mmu
@@ -146,13 +174,18 @@ tlb_flush_mmu(struct mmu_gather *tlb, un
 static inline void
 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
+	struct mmu_gather_batch *batch, *next;
+
 	tlb_flush_mmu(tlb, start, end);
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
 
-	if (tlb->pages != tlb->local)
-		free_pages((unsigned long)tlb->pages, 0);
+	for (batch = tlb->local.next; batch; batch = next) {
+		next = batch->next;
+		free_pages((unsigned long)batch, 0);
+	}
+	tlb->local.next = NULL;
 }
 
 /* tlb_remove_page
@@ -162,14 +195,23 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
  */
 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
+	struct mmu_gather_batch *batch;
+
 	tlb->need_flush = 1;
+
 	if (tlb_fast_mode(tlb)) {
 		free_page_and_swap_cache(page);
 		return;
 	}
-	tlb->pages[tlb->nr++] = page;
-	if (tlb->nr >= tlb->max)
-		tlb_flush_mmu(tlb, 0, 0);
+
+	batch = tlb->active;
+	if (batch->nr == batch->max) {
+		if (!tlb_next_batch(tlb))
+			tlb_flush_mmu(tlb, 0, 0);
+		batch = tlb->active;
+	}
+
+	batch->pages[batch->nr++] = page;
 }
 
 /**


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[PATCH 16/25] mm: Revert page_lock_anon_vma() lock annotation

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-revert_page_lock_anon_vma_lock_annotation.patch --]
[-- Type: text/plain, Size: 2200 bytes --]

Its beyond ugly and gets in the way.

Cc: Namhyung Kim <namhyung@gmail.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/rmap.h |   15 +--------------
 mm/rmap.c            |    4 +---
 2 files changed, 2 insertions(+), 17 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -243,20 +243,7 @@ int try_to_munlock(struct page *);
 /*
  * Called by memory-failure.c to kill processes.
  */
-struct anon_vma *__page_lock_anon_vma(struct page *page);
-
-static inline struct anon_vma *page_lock_anon_vma(struct page *page)
-{
-	struct anon_vma *anon_vma;
-
-	__cond_lock(RCU, anon_vma = __page_lock_anon_vma(page));
-
-	/* (void) is needed to make gcc happy */
-	(void) __cond_lock(&anon_vma->root->lock, anon_vma);
-
-	return anon_vma;
-}
-
+struct anon_vma *page_lock_anon_vma(struct page *page);
 void page_unlock_anon_vma(struct anon_vma *anon_vma);
 int page_mapped_in_vma(struct page *page, struct vm_area_struct *vma);
 
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -318,7 +318,7 @@ void __init anon_vma_init(void)
  * Getting a lock on a stable anon_vma from a page off the LRU is
  * tricky: page_lock_anon_vma rely on RCU to guard against the races.
  */
-struct anon_vma *__page_lock_anon_vma(struct page *page)
+struct anon_vma *page_lock_anon_vma(struct page *page)
 {
 	struct anon_vma *anon_vma, *root_anon_vma;
 	unsigned long anon_mapping;
@@ -352,8 +352,6 @@ struct anon_vma *__page_lock_anon_vma(st
 }
 
 void page_unlock_anon_vma(struct anon_vma *anon_vma)
-	__releases(&anon_vma->root->lock)
-	__releases(RCU)
 {
 	anon_vma_unlock(anon_vma);
 	rcu_read_unlock();


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[PATCH 17/25] mm: Improve page_lock_anon_vma() comment

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-improve_page_lock_anon_vma_comment.patch --]
[-- Type: text/plain, Size: 1981 bytes --]

A slightly more verbose comment to go along with the trickery in
page_lock_anon_vma().

Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Mel Gorman <mel@csn.ul.ie>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 mm/rmap.c |   18 ++++++++++++++++--
 1 file changed, 16 insertions(+), 2 deletions(-)

Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -315,8 +315,22 @@ void __init anon_vma_init(void)
 }
 
 /*
- * Getting a lock on a stable anon_vma from a page off the LRU is
- * tricky: page_lock_anon_vma rely on RCU to guard against the races.
+ * Getting a lock on a stable anon_vma from a page off the LRU is tricky!
+ *
+ * Since there is no serialization what so ever against page_remove_rmap()
+ * the best this function can do is return a locked anon_vma that might
+ * have been relevant to this page.
+ *
+ * The page might have been remapped to a different anon_vma or the anon_vma
+ * returned may already be freed (and even reused).
+ *
+ * All users of this function must be very careful when walking the anon_vma
+ * chain and verify that the page in question is indeed mapped in it
+ * [ something equivalent to page_mapped_in_vma() ].
+ *
+ * Since anon_vma's slab is DESTROY_BY_RCU and we know from page_remove_rmap()
+ * that the anon_vma pointer from page->mapping is valid if there is a
+ * mapcount, we can dereference the anon_vma after observing those.
  */
 struct anon_vma *page_lock_anon_vma(struct page *page)
 {


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[PATCH 18/25] mm: Rename drop_anon_vma to put_anon_vma

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-rename_drop_anon_vma_to_put_anon_vma.patch --]
[-- Type: text/plain, Size: 4640 bytes --]

The normal code pattern used in the kernel is: get/put.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/rmap.h |    4 ++--
 mm/ksm.c             |   23 +++++------------------
 mm/migrate.c         |    4 ++--
 mm/rmap.c            |    4 ++--
 4 files changed, 11 insertions(+), 24 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -87,7 +87,7 @@ static inline void get_anon_vma(struct a
 	atomic_inc(&anon_vma->external_refcount);
 }
 
-void drop_anon_vma(struct anon_vma *);
+void put_anon_vma(struct anon_vma *);
 #else
 static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
 {
@@ -102,7 +102,7 @@ static inline void get_anon_vma(struct a
 {
 }
 
-static inline void drop_anon_vma(struct anon_vma *anon_vma)
+static inline void put_anon_vma(struct anon_vma *anon_vma)
 {
 }
 #endif /* CONFIG_KSM */
Index: linux-2.6/mm/ksm.c
===================================================================
--- linux-2.6.orig/mm/ksm.c
+++ linux-2.6/mm/ksm.c
@@ -301,20 +301,6 @@ static inline int in_stable_tree(struct 
 	return rmap_item->address & STABLE_FLAG;
 }
 
-static void hold_anon_vma(struct rmap_item *rmap_item,
-			  struct anon_vma *anon_vma)
-{
-	rmap_item->anon_vma = anon_vma;
-	get_anon_vma(anon_vma);
-}
-
-static void ksm_drop_anon_vma(struct rmap_item *rmap_item)
-{
-	struct anon_vma *anon_vma = rmap_item->anon_vma;
-
-	drop_anon_vma(anon_vma);
-}
-
 /*
  * ksmd, and unmerge_and_remove_all_rmap_items(), must not touch an mm's
  * page tables after it has passed through ksm_exit() - which, if necessary,
@@ -397,7 +383,7 @@ static void break_cow(struct rmap_item *
 	 * It is not an accident that whenever we want to break COW
 	 * to undo, we also need to drop a reference to the anon_vma.
 	 */
-	ksm_drop_anon_vma(rmap_item);
+	put_anon_vma(rmap_item->anon_vma);
 
 	down_read(&mm->mmap_sem);
 	if (ksm_test_exit(mm))
@@ -466,7 +452,7 @@ static void remove_node_from_stable_tree
 			ksm_pages_sharing--;
 		else
 			ksm_pages_shared--;
-		ksm_drop_anon_vma(rmap_item);
+		put_anon_vma(rmap_item->anon_vma);
 		rmap_item->address &= PAGE_MASK;
 		cond_resched();
 	}
@@ -554,7 +540,7 @@ static void remove_rmap_item_from_tree(s
 		else
 			ksm_pages_shared--;
 
-		ksm_drop_anon_vma(rmap_item);
+		put_anon_vma(rmap_item->anon_vma);
 		rmap_item->address &= PAGE_MASK;
 
 	} else if (rmap_item->address & UNSTABLE_FLAG) {
@@ -949,7 +935,8 @@ static int try_to_merge_with_ksm_page(st
 		goto out;
 
 	/* Must get reference to anon_vma while still holding mmap_sem */
-	hold_anon_vma(rmap_item, vma->anon_vma);
+	rmap_item->anon_vma = vma->anon_vma;
+	get_anon_vma(vma->anon_vma);
 out:
 	up_read(&mm->mmap_sem);
 	return err;
Index: linux-2.6/mm/migrate.c
===================================================================
--- linux-2.6.orig/mm/migrate.c
+++ linux-2.6/mm/migrate.c
@@ -764,7 +764,7 @@ static int unmap_and_move(new_page_t get
 
 	/* Drop an anon_vma reference if we took one */
 	if (anon_vma)
-		drop_anon_vma(anon_vma);
+		put_anon_vma(anon_vma);
 
 uncharge:
 	if (!charge)
@@ -857,7 +857,7 @@ static int unmap_and_move_huge_page(new_
 		remove_migration_ptes(hpage, hpage);
 
 	if (anon_vma)
-		drop_anon_vma(anon_vma);
+		put_anon_vma(anon_vma);
 out:
 	unlock_page(hpage);
 
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -278,7 +278,7 @@ static void anon_vma_unlink(struct anon_
 	if (empty) {
 		/* We no longer need the root anon_vma */
 		if (anon_vma->root != anon_vma)
-			drop_anon_vma(anon_vma->root);
+			put_anon_vma(anon_vma->root);
 		anon_vma_free(anon_vma);
 	}
 }
@@ -1489,7 +1489,7 @@ int try_to_munlock(struct page *page)
  * we know we are the last user, nobody else can get a reference and we
  * can do the freeing without the lock.
  */
-void drop_anon_vma(struct anon_vma *anon_vma)
+void put_anon_vma(struct anon_vma *anon_vma)
 {
 	BUG_ON(atomic_read(&anon_vma->external_refcount) <= 0);
 	if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) {


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[PATCH 19/25] mm: Move anon_vma ref out from under CONFIG_KSM

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-move_anon_vma_ref_out_from_under_config_ksm.patch --]
[-- Type: text/plain, Size: 4857 bytes --]

We need an anon_vma refcount for preemptible anon_vma->lock.

Acked-by: Mel Gorman <mel@csn.ul.ie>
Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/rmap.h |   40 ++++------------------------------------
 mm/rmap.c            |   14 ++++++--------
 2 files changed, 10 insertions(+), 44 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -27,18 +27,15 @@
 struct anon_vma {
 	struct anon_vma *root;	/* Root of this anon_vma tree */
 	spinlock_t lock;	/* Serialize access to vma list */
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
-
 	/*
-	 * The external_refcount is taken by either KSM or page migration
-	 * to take a reference to an anon_vma when there is no
+	 * The refcount is taken on an anon_vma when there is no
 	 * guarantee that the vma of page tables will exist for
 	 * the duration of the operation. A caller that takes
 	 * the reference is responsible for clearing up the
 	 * anon_vma if they are the last user on release
 	 */
-	atomic_t external_refcount;
-#endif
+	atomic_t refcount;
+
 	/*
 	 * NOTE: the LSB of the head.next is set by
 	 * mm_take_all_locks() _after_ taking the above lock. So the
@@ -71,41 +68,12 @@ struct anon_vma_chain {
 };
 
 #ifdef CONFIG_MMU
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
-static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
-{
-	atomic_set(&anon_vma->external_refcount, 0);
-}
-
-static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
-{
-	return atomic_read(&anon_vma->external_refcount);
-}
-
 static inline void get_anon_vma(struct anon_vma *anon_vma)
 {
-	atomic_inc(&anon_vma->external_refcount);
+	atomic_inc(&anon_vma->refcount);
 }
 
 void put_anon_vma(struct anon_vma *);
-#else
-static inline void anonvma_external_refcount_init(struct anon_vma *anon_vma)
-{
-}
-
-static inline int anonvma_external_refcount(struct anon_vma *anon_vma)
-{
-	return 0;
-}
-
-static inline void get_anon_vma(struct anon_vma *anon_vma)
-{
-}
-
-static inline void put_anon_vma(struct anon_vma *anon_vma)
-{
-}
-#endif /* CONFIG_KSM */
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -272,7 +272,7 @@ static void anon_vma_unlink(struct anon_
 	list_del(&anon_vma_chain->same_anon_vma);
 
 	/* We must garbage collect the anon_vma if it's empty */
-	empty = list_empty(&anon_vma->head) && !anonvma_external_refcount(anon_vma);
+	empty = list_empty(&anon_vma->head) && !atomic_read(&anon_vma->refcount);
 	anon_vma_unlock(anon_vma);
 
 	if (empty) {
@@ -303,7 +303,7 @@ static void anon_vma_ctor(void *data)
 	struct anon_vma *anon_vma = data;
 
 	spin_lock_init(&anon_vma->lock);
-	anonvma_external_refcount_init(anon_vma);
+	atomic_set(&anon_vma->refcount, 0);
 	INIT_LIST_HEAD(&anon_vma->head);
 }
 
@@ -1482,7 +1482,6 @@ int try_to_munlock(struct page *page)
 		return try_to_unmap_file(page, TTU_MUNLOCK);
 }
 
-#if defined(CONFIG_KSM) || defined(CONFIG_MIGRATION)
 /*
  * Drop an anon_vma refcount, freeing the anon_vma and anon_vma->root
  * if necessary.  Be careful to do all the tests under the lock.  Once
@@ -1491,8 +1490,8 @@ int try_to_munlock(struct page *page)
  */
 void put_anon_vma(struct anon_vma *anon_vma)
 {
-	BUG_ON(atomic_read(&anon_vma->external_refcount) <= 0);
-	if (atomic_dec_and_lock(&anon_vma->external_refcount, &anon_vma->root->lock)) {
+	BUG_ON(atomic_read(&anon_vma->refcount) <= 0);
+	if (atomic_dec_and_lock(&anon_vma->refcount, &anon_vma->root->lock)) {
 		struct anon_vma *root = anon_vma->root;
 		int empty = list_empty(&anon_vma->head);
 		int last_root_user = 0;
@@ -1503,8 +1502,8 @@ void put_anon_vma(struct anon_vma *anon_
 		 * the refcount on the root and check if we need to free it.
 		 */
 		if (empty && anon_vma != root) {
-			BUG_ON(atomic_read(&root->external_refcount) <= 0);
-			last_root_user = atomic_dec_and_test(&root->external_refcount);
+			BUG_ON(atomic_read(&root->refcount) <= 0);
+			last_root_user = atomic_dec_and_test(&root->refcount);
 			root_empty = list_empty(&root->head);
 		}
 		anon_vma_unlock(anon_vma);
@@ -1516,7 +1515,6 @@ void put_anon_vma(struct anon_vma *anon_
 		}
 	}
 }
-#endif
 
 #ifdef CONFIG_MIGRATION
 /*


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[PATCH 20/25] mm: Simplify anon_vma refcounts

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-simplify_anon_vma_refcounts.patch --]
[-- Type: text/plain, Size: 6384 bytes --]

This patch changes the anon_vma refcount to be 0 when the object is
free. It does this by adding 1 ref to being in use in the anon_vma
structure (iow. the anon_vma->head list is not empty).

This allows a simpler release scheme without having to check both the
refcount and the list as well as avoids taking a ref for each entry
on the list.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/rmap.h |   11 +++++--
 mm/rmap.c            |   79 ++++++++++++++++++---------------------------------
 2 files changed, 37 insertions(+), 53 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -73,7 +73,13 @@ static inline void get_anon_vma(struct a
 	atomic_inc(&anon_vma->refcount);
 }
 
-void put_anon_vma(struct anon_vma *);
+void __put_anon_vma(struct anon_vma *anon_vma);
+
+static inline void put_anon_vma(struct anon_vma *anon_vma)
+{
+	if (atomic_dec_and_test(&anon_vma->refcount))
+		__put_anon_vma(anon_vma);
+}
 
 static inline struct anon_vma *page_anon_vma(struct page *page)
 {
@@ -116,7 +122,6 @@ void unlink_anon_vmas(struct vm_area_str
 int anon_vma_clone(struct vm_area_struct *, struct vm_area_struct *);
 int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
 void __anon_vma_link(struct vm_area_struct *);
-void anon_vma_free(struct anon_vma *);
 
 static inline void anon_vma_merge(struct vm_area_struct *vma,
 				  struct vm_area_struct *next)
@@ -125,6 +130,8 @@ static inline void anon_vma_merge(struct
 	unlink_anon_vmas(next);
 }
 
+struct anon_vma *page_get_anon_vma(struct page *page);
+
 /*
  * rmap interfaces called when adding or removing pte of page
  */
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -67,11 +67,24 @@ static struct kmem_cache *anon_vma_chain
 
 static inline struct anon_vma *anon_vma_alloc(void)
 {
-	return kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
+	struct anon_vma *anon_vma;
+
+	anon_vma = kmem_cache_alloc(anon_vma_cachep, GFP_KERNEL);
+	if (anon_vma) {
+		atomic_set(&anon_vma->refcount, 1);
+		/*
+		 * Initialise the anon_vma root to point to itself. If called
+		 * from fork, the root will be reset to the parents anon_vma.
+		 */
+		anon_vma->root = anon_vma;
+	}
+
+	return anon_vma;
 }
 
-void anon_vma_free(struct anon_vma *anon_vma)
+static inline void anon_vma_free(struct anon_vma *anon_vma)
 {
+	VM_BUG_ON(atomic_read(&anon_vma->refcount));
 	kmem_cache_free(anon_vma_cachep, anon_vma);
 }
 
@@ -133,11 +146,6 @@ int anon_vma_prepare(struct vm_area_stru
 			if (unlikely(!anon_vma))
 				goto out_enomem_free_avc;
 			allocated = anon_vma;
-			/*
-			 * This VMA had no anon_vma yet.  This anon_vma is
-			 * the root of any anon_vma tree that might form.
-			 */
-			anon_vma->root = anon_vma;
 		}
 
 		anon_vma_lock(anon_vma);
@@ -156,7 +164,7 @@ int anon_vma_prepare(struct vm_area_stru
 		anon_vma_unlock(anon_vma);
 
 		if (unlikely(allocated))
-			anon_vma_free(allocated);
+			put_anon_vma(allocated);
 		if (unlikely(avc))
 			anon_vma_chain_free(avc);
 	}
@@ -241,9 +249,9 @@ int anon_vma_fork(struct vm_area_struct 
 	 */
 	anon_vma->root = pvma->anon_vma->root;
 	/*
-	 * With KSM refcounts, an anon_vma can stay around longer than the
-	 * process it belongs to.  The root anon_vma needs to be pinned
-	 * until this anon_vma is freed, because the lock lives in the root.
+	 * With refcounts, an anon_vma can stay around longer than the
+	 * process it belongs to. The root anon_vma needs to be pinned until
+	 * this anon_vma is freed, because the lock lives in the root.
 	 */
 	get_anon_vma(anon_vma->root);
 	/* Mark this anon_vma as the one where our new (COWed) pages go. */
@@ -253,7 +261,7 @@ int anon_vma_fork(struct vm_area_struct 
 	return 0;
 
  out_error_free_anon_vma:
-	anon_vma_free(anon_vma);
+	put_anon_vma(anon_vma);
  out_error:
 	unlink_anon_vmas(vma);
 	return -ENOMEM;
@@ -272,15 +280,11 @@ static void anon_vma_unlink(struct anon_
 	list_del(&anon_vma_chain->same_anon_vma);
 
 	/* We must garbage collect the anon_vma if it's empty */
-	empty = list_empty(&anon_vma->head) && !atomic_read(&anon_vma->refcount);
+	empty = list_empty(&anon_vma->head);
 	anon_vma_unlock(anon_vma);
 
-	if (empty) {
-		/* We no longer need the root anon_vma */
-		if (anon_vma->root != anon_vma)
-			put_anon_vma(anon_vma->root);
-		anon_vma_free(anon_vma);
-	}
+	if (empty)
+		put_anon_vma(anon_vma);
 }
 
 void unlink_anon_vmas(struct vm_area_struct *vma)
@@ -1482,38 +1486,11 @@ int try_to_munlock(struct page *page)
 		return try_to_unmap_file(page, TTU_MUNLOCK);
 }
 
-/*
- * Drop an anon_vma refcount, freeing the anon_vma and anon_vma->root
- * if necessary.  Be careful to do all the tests under the lock.  Once
- * we know we are the last user, nobody else can get a reference and we
- * can do the freeing without the lock.
- */
-void put_anon_vma(struct anon_vma *anon_vma)
-{
-	BUG_ON(atomic_read(&anon_vma->refcount) <= 0);
-	if (atomic_dec_and_lock(&anon_vma->refcount, &anon_vma->root->lock)) {
-		struct anon_vma *root = anon_vma->root;
-		int empty = list_empty(&anon_vma->head);
-		int last_root_user = 0;
-		int root_empty = 0;
-
-		/*
-		 * The refcount on a non-root anon_vma got dropped.  Drop
-		 * the refcount on the root and check if we need to free it.
-		 */
-		if (empty && anon_vma != root) {
-			BUG_ON(atomic_read(&root->refcount) <= 0);
-			last_root_user = atomic_dec_and_test(&root->refcount);
-			root_empty = list_empty(&root->head);
-		}
-		anon_vma_unlock(anon_vma);
-
-		if (empty) {
-			anon_vma_free(anon_vma);
-			if (root_empty && last_root_user)
-				anon_vma_free(root);
-		}
-	}
+void __put_anon_vma(struct anon_vma *anon_vma)
+{
+	if (anon_vma->root != anon_vma)
+		put_anon_vma(anon_vma->root);
+	anon_vma_free(anon_vma);
 }
 
 #ifdef CONFIG_MIGRATION


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Re: [PATCH 20/25] mm: Simplify anon_vma refcounts

[Linus Torvalds]

On Wed, Jan 26, 2011 at 3:31 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> This patch changes the anon_vma refcount to be 0 when the object is
> free. It does this by adding 1 ref to being in use in the anon_vma
> structure (iow. the anon_vma->head list is not empty).

Why is this patch part of this series, rather than being an
independent patch before the whole series?

I think this part of the series is the only total no-brainer, ie we
should have done this from the beginning. The preemptability stuff I'm
more nervous about (performance issues? semantic differences?)

             Linus

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Re: [PATCH 20/25] mm: Simplify anon_vma refcounts

[Peter Zijlstra]

On Wed, 2011-01-26 at 06:16 +1000, Linus Torvalds wrote:
> On Wed, Jan 26, 2011 at 3:31 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
> >
> > This patch changes the anon_vma refcount to be 0 when the object is
> > free. It does this by adding 1 ref to being in use in the anon_vma
> > structure (iow. the anon_vma->head list is not empty).
> 
> Why is this patch part of this series, rather than being an
> independent patch before the whole series?
> 
> I think this part of the series is the only total no-brainer, ie we
> should have done this from the beginning. The preemptability stuff I'm
> more nervous about (performance issues? semantic differences?)

It relies on patch 19, which moves the anon_vma refcount out from under
CONFIG_goo.

If however you like it, I can move 19 and this patch up to the start and
have that go your way soon.

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Re: [PATCH 20/25] mm: Simplify anon_vma refcounts

[Linus Torvalds]

On Wed, Jan 26, 2011 at 6:31 AM, Peter Zijlstra <a.p.zijlstra@chello.nl> wrote:
>
> It relies on patch 19, which moves the anon_vma refcount out from under
> CONFIG_goo.
>
> If however you like it, I can move 19 and this patch up to the start and
> have that go your way soon.

So I'd prefer that, and keeping this issue separate. It seems like a
rather independent cleanup to me (there may be others, this is the
only one I reacted to when skimming through the series - reading email
using my small laptop screen and a somewhat flaky 3g hotspot
connection isn't exactly amenable to deep and careful thinking ;).

             Linus

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[PATCH 21/25] mm: Use refcounts for page_lock_anon_vma()

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-use_refcounts_for_page_lock_anon_vma.patch --]
[-- Type: text/plain, Size: 4295 bytes --]

Convert page_lock_anon_vma() over to use refcounts. This is done to
prepare for the conversion of anon_vma from spinlock to mutex.

Sadly this inceases the cost of page_lock_anon_vma() from one to two
atomics, a follow up patch addresses this, lets keep that simple for
now.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 mm/migrate.c |   17 ++++-------------
 mm/rmap.c    |   42 +++++++++++++++++++++++++++---------------
 2 files changed, 31 insertions(+), 28 deletions(-)

Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -336,9 +336,9 @@ void __init anon_vma_init(void)
  * that the anon_vma pointer from page->mapping is valid if there is a
  * mapcount, we can dereference the anon_vma after observing those.
  */
-struct anon_vma *page_lock_anon_vma(struct page *page)
+struct anon_vma *page_get_anon_vma(struct page *page)
 {
-	struct anon_vma *anon_vma, *root_anon_vma;
+	struct anon_vma *anon_vma = NULL;
 	unsigned long anon_mapping;
 
 	rcu_read_lock();
@@ -349,30 +349,42 @@ struct anon_vma *page_lock_anon_vma(stru
 		goto out;
 
 	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
-	root_anon_vma = ACCESS_ONCE(anon_vma->root);
-	spin_lock(&root_anon_vma->lock);
+	if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+		anon_vma = NULL;
+		goto out;
+	}
 
 	/*
 	 * If this page is still mapped, then its anon_vma cannot have been
-	 * freed.  But if it has been unmapped, we have no security against
-	 * the anon_vma structure being freed and reused (for another anon_vma:
-	 * SLAB_DESTROY_BY_RCU guarantees that - so the spin_lock above cannot
-	 * corrupt): with anon_vma_prepare() or anon_vma_fork() redirecting
-	 * anon_vma->root before page_unlock_anon_vma() is called to unlock.
+	 * freed.  But if it has been unmapped, we have no security against the
+	 * anon_vma structure being freed and reused (for another anon_vma:
+	 * SLAB_DESTROY_BY_RCU guarantees that - so the atomic_inc_not_zero()
+	 * above cannot corrupt).
 	 */
-	if (page_mapped(page))
-		return anon_vma;
-
-	spin_unlock(&root_anon_vma->lock);
+	if (!page_mapped(page)) {
+		put_anon_vma(anon_vma);
+		anon_vma = NULL;
+	}
 out:
 	rcu_read_unlock();
-	return NULL;
+
+	return anon_vma;
+}
+
+struct anon_vma *page_lock_anon_vma(struct page *page)
+{
+	struct anon_vma *anon_vma = page_get_anon_vma(page);
+
+	if (anon_vma)
+		anon_vma_lock(anon_vma);
+
+	return anon_vma;
 }
 
 void page_unlock_anon_vma(struct anon_vma *anon_vma)
 {
 	anon_vma_unlock(anon_vma);
-	rcu_read_unlock();
+	put_anon_vma(anon_vma);
 }
 
 /*
Index: linux-2.6/mm/migrate.c
===================================================================
--- linux-2.6.orig/mm/migrate.c
+++ linux-2.6/mm/migrate.c
@@ -703,15 +703,11 @@ static int unmap_and_move(new_page_t get
 		 * Only page_lock_anon_vma() understands the subtleties of
 		 * getting a hold on an anon_vma from outside one of its mms.
 		 */
-		anon_vma = page_lock_anon_vma(page);
+		anon_vma = page_get_anon_vma(page);
 		if (anon_vma) {
 			/*
-			 * Take a reference count on the anon_vma if the
-			 * page is mapped so that it is guaranteed to
-			 * exist when the page is remapped later
+			 * Anon page
 			 */
-			get_anon_vma(anon_vma);
-			page_unlock_anon_vma(anon_vma);
 		} else if (PageSwapCache(page)) {
 			/*
 			 * We cannot be sure that the anon_vma of an unmapped
@@ -840,13 +836,8 @@ static int unmap_and_move_huge_page(new_
 		lock_page(hpage);
 	}
 
-	if (PageAnon(hpage)) {
-		anon_vma = page_lock_anon_vma(hpage);
-		if (anon_vma) {
-			get_anon_vma(anon_vma);
-			page_unlock_anon_vma(anon_vma);
-		}
-	}
+	if (PageAnon(hpage))
+		anon_vma = page_get_anon_vma(hpage);
 
 	try_to_unmap(hpage, TTU_MIGRATION|TTU_IGNORE_MLOCK|TTU_IGNORE_ACCESS);
 


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[PATCH 22/25] mm: Convert anon_vma->lock to a mutex

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-anon_vma-lock_to_mutexes.patch --]
[-- Type: text/plain, Size: 7975 bytes --]

Straight fwd conversion of anon_vma->lock to a mutex.

Acked-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/huge_mm.h      |    8 ++------
 include/linux/mmu_notifier.h |    2 +-
 include/linux/rmap.h         |   14 +++++++-------
 mm/huge_memory.c             |    4 ++--
 mm/mmap.c                    |   10 +++++-----
 mm/rmap.c                    |    8 ++++----
 6 files changed, 21 insertions(+), 25 deletions(-)

Index: linux-2.6/include/linux/rmap.h
===================================================================
--- linux-2.6.orig/include/linux/rmap.h
+++ linux-2.6/include/linux/rmap.h
@@ -7,7 +7,7 @@
 #include <linux/list.h>
 #include <linux/slab.h>
 #include <linux/mm.h>
-#include <linux/spinlock.h>
+#include <linux/mutex.h>
 #include <linux/memcontrol.h>
 
 /*
@@ -26,7 +26,7 @@
  */
 struct anon_vma {
 	struct anon_vma *root;	/* Root of this anon_vma tree */
-	spinlock_t lock;	/* Serialize access to vma list */
+	struct mutex mutex;	/* Serialize access to vma list */
 	/*
 	 * The refcount is taken on an anon_vma when there is no
 	 * guarantee that the vma of page tables will exist for
@@ -64,7 +64,7 @@ struct anon_vma_chain {
 	struct vm_area_struct *vma;
 	struct anon_vma *anon_vma;
 	struct list_head same_vma;   /* locked by mmap_sem & page_table_lock */
-	struct list_head same_anon_vma;	/* locked by anon_vma->lock */
+	struct list_head same_anon_vma;	/* locked by anon_vma->mutex */
 };
 
 #ifdef CONFIG_MMU
@@ -93,24 +93,24 @@ static inline void vma_lock_anon_vma(str
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 	if (anon_vma)
-		spin_lock(&anon_vma->root->lock);
+		mutex_lock(&anon_vma->root->mutex);
 }
 
 static inline void vma_unlock_anon_vma(struct vm_area_struct *vma)
 {
 	struct anon_vma *anon_vma = vma->anon_vma;
 	if (anon_vma)
-		spin_unlock(&anon_vma->root->lock);
+		mutex_unlock(&anon_vma->root->mutex);
 }
 
 static inline void anon_vma_lock(struct anon_vma *anon_vma)
 {
-	spin_lock(&anon_vma->root->lock);
+	mutex_lock(&anon_vma->root->mutex);
 }
 
 static inline void anon_vma_unlock(struct anon_vma *anon_vma)
 {
-	spin_unlock(&anon_vma->root->lock);
+	mutex_unlock(&anon_vma->root->mutex);
 }
 
 /*
Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -25,7 +25,7 @@
  *   mm->mmap_sem
  *     page->flags PG_locked (lock_page)
  *       mapping->i_mmap_mutex
- *         anon_vma->lock
+ *         anon_vma->mutex
  *           mm->page_table_lock or pte_lock
  *             zone->lru_lock (in mark_page_accessed, isolate_lru_page)
  *             swap_lock (in swap_duplicate, swap_info_get)
@@ -39,7 +39,7 @@
  *
  * (code doesn't rely on that order so it could be switched around)
  * ->tasklist_lock
- *   anon_vma->lock      (memory_failure, collect_procs_anon)
+ *   anon_vma->mutex      (memory_failure, collect_procs_anon)
  *     pte map lock
  */
 
@@ -306,7 +306,7 @@ static void anon_vma_ctor(void *data)
 {
 	struct anon_vma *anon_vma = data;
 
-	spin_lock_init(&anon_vma->lock);
+	mutex_init(&anon_vma->mutex);
 	atomic_set(&anon_vma->refcount, 0);
 	INIT_LIST_HEAD(&anon_vma->head);
 }
@@ -1129,7 +1129,7 @@ int try_to_unmap_one(struct page *page, 
 	/*
 	 * We need mmap_sem locking, Otherwise VM_LOCKED check makes
 	 * unstable result and race. Plus, We can't wait here because
-	 * we now hold anon_vma->lock or mapping->i_mmap_mutex.
+	 * we now hold anon_vma->mutex or mapping->i_mmap_mutex.
 	 * if trylock failed, the page remain in evictable lru and later
 	 * vmscan could retry to move the page to unevictable lru if the
 	 * page is actually mlocked.
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c
+++ linux-2.6/mm/mmap.c
@@ -2523,15 +2523,15 @@ static void vm_lock_anon_vma(struct mm_s
 		 * The LSB of head.next can't change from under us
 		 * because we hold the mm_all_locks_mutex.
 		 */
-		spin_lock_nest_lock(&anon_vma->root->lock, &mm->mmap_sem);
+		mutex_lock_nest_lock(&anon_vma->root->mutex, &mm->mmap_sem);
 		/*
 		 * We can safely modify head.next after taking the
-		 * anon_vma->root->lock. If some other vma in this mm shares
+		 * anon_vma->root->mutex. If some other vma in this mm shares
 		 * the same anon_vma we won't take it again.
 		 *
 		 * No need of atomic instructions here, head.next
 		 * can't change from under us thanks to the
-		 * anon_vma->root->lock.
+		 * anon_vma->root->mutex.
 		 */
 		if (__test_and_set_bit(0, (unsigned long *)
 				       &anon_vma->root->head.next))
@@ -2580,7 +2580,7 @@ static void vm_lock_mapping(struct mm_st
  * vma in this mm is backed by the same anon_vma or address_space.
  *
  * We can take all the locks in random order because the VM code
- * taking i_mmap_mutex or anon_vma->lock outside the mmap_sem never
+ * taking i_mmap_mutex or anon_vma->mutex outside the mmap_sem never
  * takes more than one of them in a row. Secondly we're protected
  * against a concurrent mm_take_all_locks() by the mm_all_locks_mutex.
  *
@@ -2636,7 +2636,7 @@ static void vm_unlock_anon_vma(struct an
 		 *
 		 * No need of atomic instructions here, head.next
 		 * can't change from under us until we release the
-		 * anon_vma->root->lock.
+		 * anon_vma->root->mutex.
 		 */
 		if (!__test_and_clear_bit(0, (unsigned long *)
 					  &anon_vma->root->head.next))
Index: linux-2.6/include/linux/mmu_notifier.h
===================================================================
--- linux-2.6.orig/include/linux/mmu_notifier.h
+++ linux-2.6/include/linux/mmu_notifier.h
@@ -150,7 +150,7 @@ struct mmu_notifier_ops {
  * Therefore notifier chains can only be traversed when either
  *
  * 1. mmap_sem is held.
- * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->lock).
+ * 2. One of the reverse map locks is held (i_mmap_mutex or anon_vma->mutex).
  * 3. No other concurrent thread can access the list (release)
  */
 struct mmu_notifier {
Index: linux-2.6/mm/huge_memory.c
===================================================================
--- linux-2.6.orig/mm/huge_memory.c
+++ linux-2.6/mm/huge_memory.c
@@ -1128,7 +1128,7 @@ static int __split_huge_page_splitting(s
 		 * We can't temporarily set the pmd to null in order
 		 * to split it, the pmd must remain marked huge at all
 		 * times or the VM won't take the pmd_trans_huge paths
-		 * and it won't wait on the anon_vma->root->lock to
+		 * and it won't wait on the anon_vma->root->mutex to
 		 * serialize against split_huge_page*.
 		 */
 		pmdp_splitting_flush_notify(vma, address, pmd);
@@ -1315,7 +1315,7 @@ static int __split_huge_page_map(struct 
 	return ret;
 }
 
-/* must be called with anon_vma->root->lock hold */
+/* must be called with anon_vma->root->mutex hold */
 static void __split_huge_page(struct page *page,
 			      struct anon_vma *anon_vma)
 {
Index: linux-2.6/include/linux/huge_mm.h
===================================================================
--- linux-2.6.orig/include/linux/huge_mm.h
+++ linux-2.6/include/linux/huge_mm.h
@@ -91,12 +91,8 @@ extern void __split_huge_page_pmd(struct
 #define wait_split_huge_page(__anon_vma, __pmd)				\
 	do {								\
 		pmd_t *____pmd = (__pmd);				\
-		spin_unlock_wait(&(__anon_vma)->root->lock);		\
-		/*							\
-		 * spin_unlock_wait() is just a loop in C and so the	\
-		 * CPU can reorder anything around it.			\
-		 */							\
-		smp_mb();						\
+		anon_vma_lock(__anon_vma);				\
+		anon_vma_unlock(__anon_vma);				\
 		BUG_ON(pmd_trans_splitting(*____pmd) ||			\
 		       pmd_trans_huge(*____pmd));			\
 	} while (0)


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Re: [PATCH 22/25] mm: Convert anon_vma->lock to a mutex

[KOSAKI Motohiro]

> Straight fwd conversion of anon_vma->lock to a mutex.
> 
> Acked-by: Hugh Dickins <hughd@google.com>
> Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>

Don't I ack this series at previous iteration? If not, Hmmm.. I haven't remenber
the reason. Anyway
	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>




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Re: [PATCH 22/25] mm: Convert anon_vma->lock to a mutex

[Peter Zijlstra]

On Thu, 2011-02-03 at 14:27 +0900, KOSAKI Motohiro wrote:
> > Straight fwd conversion of anon_vma->lock to a mutex.
> > 
> > Acked-by: Hugh Dickins <hughd@google.com>
> > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> 
> Don't I ack this series at previous iteration? If not, Hmmm.. I haven't remenber
> the reason.

I got a +1 email from you on the spinlock to mutex conversion patch, I
wasn't quite sure to what tag that translated.

>  Anyway
> 	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>

Is this for this particular patch, or for the series? 

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Re: [PATCH 22/25] mm: Convert anon_vma->lock to a mutex

[KOSAKI Motohiro]

> On Thu, 2011-02-03 at 14:27 +0900, KOSAKI Motohiro wrote:
> > > Straight fwd conversion of anon_vma->lock to a mutex.
> > > 
> > > Acked-by: Hugh Dickins <hughd@google.com>
> > > Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
> > 
> > Don't I ack this series at previous iteration? If not, Hmmm.. I haven't remenber
> > the reason.
> 
> I got a +1 email from you on the spinlock to mutex conversion patch, I
> wasn't quite sure to what tag that translated.

I'm sorry. Maybe Im busy and I wrote unkindly mail. yes, it's my fault.


> >  Anyway
> > 	Reviewed-by: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> 
> Is this for this particular patch, or for the series? 

series. please.


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[PATCH 23/25] mm: Optimize page_lock_anon_vma() fast-path

[Peter Zijlstra]

[-- Attachment #1: peter_zijlstra-mm-optimize_page_lock_anon_vma_fast-path.patch --]
[-- Type: text/plain, Size: 3615 bytes --]

Optimize the page_lock_anon_vma() fast path to be one LOCKed op,
instead of two.

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 mm/rmap.c |   82 ++++++++++++++++++++++++++++++++++++++++++++++++++++++++++----
 1 file changed, 78 insertions(+), 4 deletions(-)

Index: linux-2.6/mm/rmap.c
===================================================================
--- linux-2.6.orig/mm/rmap.c
+++ linux-2.6/mm/rmap.c
@@ -371,20 +371,75 @@ struct anon_vma *page_get_anon_vma(struc
 	return anon_vma;
 }
 
+/*
+ * Similar to page_get_anon_vma() except it locks the anon_vma.
+ *
+ * Its a little more complex as it tries to keep the fast path to a single
+ * atomic op -- the trylock. If we fail the trylock, we fall back to getting a
+ * reference like with page_get_anon_vma() and then block on the mutex.
+ */
 struct anon_vma *page_lock_anon_vma(struct page *page)
 {
-	struct anon_vma *anon_vma = page_get_anon_vma(page);
+	struct anon_vma *anon_vma = NULL;
+	unsigned long anon_mapping;
 
-	if (anon_vma)
-		anon_vma_lock(anon_vma);
+	rcu_read_lock();
+	anon_mapping = (unsigned long) ACCESS_ONCE(page->mapping);
+	if ((anon_mapping & PAGE_MAPPING_FLAGS) != PAGE_MAPPING_ANON)
+		goto out;
+	if (!page_mapped(page))
+		goto out;
+
+	anon_vma = (struct anon_vma *) (anon_mapping - PAGE_MAPPING_ANON);
+	if (mutex_trylock(&anon_vma->root->mutex)) {
+		/*
+		 * If we observe a !0 refcount, then holding the lock ensures
+		 * the anon_vma will not go away, see __put_anon_vma().
+		 */
+		if (!atomic_read(&anon_vma->refcount)) {
+			anon_vma_unlock(anon_vma);
+			anon_vma = NULL;
+		}
+		goto out;
+	}
+
+	/* trylock failed, we got to sleep */
+	if (!atomic_inc_not_zero(&anon_vma->refcount)) {
+		anon_vma = NULL;
+		goto out;
+	}
+
+	if (!page_mapped(page)) {
+		put_anon_vma(anon_vma);
+		anon_vma = NULL;
+		goto out;
+	}
+
+	/* we pinned the anon_vma, its safe to sleep */
+	rcu_read_unlock();
+	anon_vma_lock(anon_vma);
+
+	if (atomic_dec_and_test(&anon_vma->refcount)) {
+		/*
+		 * Oops, we held the last refcount, release the lock
+		 * and bail -- can't simply use put_anon_vma() because
+		 * we'll deadlock on the anon_vma_lock() recursion.
+		 */
+		anon_vma_unlock(anon_vma);
+		__put_anon_vma(anon_vma);
+		anon_vma = NULL;
+	}
 
 	return anon_vma;
+
+out:
+	rcu_read_unlock();
+	return anon_vma;
 }
 
 void page_unlock_anon_vma(struct anon_vma *anon_vma)
 {
 	anon_vma_unlock(anon_vma);
-	put_anon_vma(anon_vma);
 }
 
 /*
@@ -1500,6 +1555,25 @@ int try_to_munlock(struct page *page)
 
 void __put_anon_vma(struct anon_vma *anon_vma)
 {
+	/*
+	 * Synchronize against page_lock_anon_vma() such that
+	 * we can safely hold the lock without the anon_vma getting
+	 * freed.
+	 *
+	 * Relies on the full mb implied by the atomic_dec_and_test() from
+	 * put_anon_vma() against the lock implied by mutex_trylock() from
+	 * page_lock_anon_vma(). This orders:
+	 *
+	 * page_lock_anon_vma()		VS	put_anon_vma()
+	 *   mutex_trylock()			  atomic_dec_and_test()
+	 *   LOCK				  MB
+	 *   atomic_read()			  mutex_is_locked()
+	 */
+	if (mutex_is_locked(&anon_vma->root->mutex)) {
+		anon_vma_lock(anon_vma);
+		anon_vma_unlock(anon_vma);
+	}
+
 	if (anon_vma->root != anon_vma)
 		put_anon_vma(anon_vma->root);
 	anon_vma_free(anon_vma);


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[PATCH 24/25] mm: Remove i_mmap_mutex lockbreak

[Peter Zijlstra]

[-- Attachment #1: mm-fix-zap_block_size.patch --]
[-- Type: text/plain, Size: 16426 bytes --]

Hugh says:
 "The only significant loser, I think, would be page reclaim (when
  concurrent with truncation): could spin for a long time waiting for
  the i_mmap_mutex it expects would soon be dropped? "

Counter points:
 - cpu contention makes the spin stop (need_resched())
 - zap pages should be freeing pages at a higher rate than reclaim
   ever can
 - shouldn't hold up reclaim more than lock_page() would

If we're going to do this, we can remove the mutex_is_contended()
patch from this series.

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 include/linux/fs.h       |    1 
 include/linux/mm.h       |    2 
 include/linux/mm_types.h |    1 
 kernel/fork.c            |    1 
 mm/memory.c              |  191 ++++++-----------------------------------------
 mm/mmap.c                |   13 ---
 mm/mremap.c              |    3 
 7 files changed, 27 insertions(+), 185 deletions(-)

Index: linux-2.6/include/linux/mm.h
===================================================================
--- linux-2.6.orig/include/linux/mm.h
+++ linux-2.6/include/linux/mm.h
@@ -876,8 +876,6 @@ struct zap_details {
 	struct address_space *check_mapping;	/* Check page->mapping if set */
 	pgoff_t	first_index;			/* Lowest page->index to unmap */
 	pgoff_t last_index;			/* Highest page->index to unmap */
-	struct mutex *i_mmap_mutex;		/* For unmap_mapping_range: */
-	unsigned long truncate_count;		/* Compare vm_truncate_count */
 };
 
 struct page *vm_normal_page(struct vm_area_struct *vma, unsigned long addr,
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -986,12 +986,12 @@ int copy_page_range(struct mm_struct *ds
 static unsigned long zap_pte_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma, pmd_t *pmd,
 				unsigned long addr, unsigned long end,
-				long *zap_work, struct zap_details *details)
+				struct zap_details *details)
 {
 	struct mm_struct *mm = tlb->mm;
-	pte_t *pte;
-	spinlock_t *ptl;
 	int rss[NR_MM_COUNTERS];
+	spinlock_t *ptl;
+	pte_t *pte;
 
 	init_rss_vec(rss);
 
@@ -1000,12 +1000,9 @@ static unsigned long zap_pte_range(struc
 	do {
 		pte_t ptent = *pte;
 		if (pte_none(ptent)) {
-			(*zap_work)--;
 			continue;
 		}
 
-		(*zap_work) -= PAGE_SIZE;
-
 		if (pte_present(ptent)) {
 			struct page *page;
 
@@ -1072,7 +1069,7 @@ static unsigned long zap_pte_range(struc
 				print_bad_pte(vma, addr, ptent, NULL);
 		}
 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
-	} while (pte++, addr += PAGE_SIZE, (addr != end && *zap_work > 0));
+	} while (pte++, addr += PAGE_SIZE, addr != end);
 
 	add_mm_rss_vec(mm, rss);
 	arch_leave_lazy_mmu_mode();
@@ -1084,7 +1081,7 @@ static unsigned long zap_pte_range(struc
 static inline unsigned long zap_pmd_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma, pud_t *pud,
 				unsigned long addr, unsigned long end,
-				long *zap_work, struct zap_details *details)
+				struct zap_details *details)
 {
 	pmd_t *pmd;
 	unsigned long next;
@@ -1096,19 +1093,15 @@ static inline unsigned long zap_pmd_rang
 			if (next-addr != HPAGE_PMD_SIZE) {
 				VM_BUG_ON(!rwsem_is_locked(&tlb->mm->mmap_sem));
 				split_huge_page_pmd(vma->vm_mm, pmd);
-			} else if (zap_huge_pmd(tlb, vma, pmd)) {
-				(*zap_work)--;
+			} else if (zap_huge_pmd(tlb, vma, pmd))
 				continue;
-			}
 			/* fall through */
 		}
-		if (pmd_none_or_clear_bad(pmd)) {
-			(*zap_work)--;
+		if (pmd_none_or_clear_bad(pmd))
 			continue;
-		}
-		next = zap_pte_range(tlb, vma, pmd, addr, next,
-						zap_work, details);
-	} while (pmd++, addr = next, (addr != end && *zap_work > 0));
+		next = zap_pte_range(tlb, vma, pmd, addr, next, details);
+		cond_resched();
+	} while (pmd++, addr = next, addr != end);
 
 	return addr;
 }
@@ -1116,7 +1109,7 @@ static inline unsigned long zap_pmd_rang
 static inline unsigned long zap_pud_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma, pgd_t *pgd,
 				unsigned long addr, unsigned long end,
-				long *zap_work, struct zap_details *details)
+				struct zap_details *details)
 {
 	pud_t *pud;
 	unsigned long next;
@@ -1124,13 +1117,10 @@ static inline unsigned long zap_pud_rang
 	pud = pud_offset(pgd, addr);
 	do {
 		next = pud_addr_end(addr, end);
-		if (pud_none_or_clear_bad(pud)) {
-			(*zap_work)--;
+		if (pud_none_or_clear_bad(pud))
 			continue;
-		}
-		next = zap_pmd_range(tlb, vma, pud, addr, next,
-						zap_work, details);
-	} while (pud++, addr = next, (addr != end && *zap_work > 0));
+		next = zap_pmd_range(tlb, vma, pud, addr, next, details);
+	} while (pud++, addr = next, addr != end);
 
 	return addr;
 }
@@ -1138,7 +1128,7 @@ static inline unsigned long zap_pud_rang
 static unsigned long unmap_page_range(struct mmu_gather *tlb,
 				struct vm_area_struct *vma,
 				unsigned long addr, unsigned long end,
-				long *zap_work, struct zap_details *details)
+				struct zap_details *details)
 {
 	pgd_t *pgd;
 	unsigned long next;
@@ -1152,13 +1142,10 @@ static unsigned long unmap_page_range(st
 	pgd = pgd_offset(vma->vm_mm, addr);
 	do {
 		next = pgd_addr_end(addr, end);
-		if (pgd_none_or_clear_bad(pgd)) {
-			(*zap_work)--;
+		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		}
-		next = zap_pud_range(tlb, vma, pgd, addr, next,
-						zap_work, details);
-	} while (pgd++, addr = next, (addr != end && *zap_work > 0));
+		next = zap_pud_range(tlb, vma, pgd, addr, next, details);
+	} while (pgd++, addr = next, addr != end);
 	tlb_end_vma(tlb, vma);
 	mem_cgroup_uncharge_end();
 
@@ -1203,9 +1190,7 @@ unsigned long unmap_vmas(struct mmu_gath
 		unsigned long end_addr, unsigned long *nr_accounted,
 		struct zap_details *details)
 {
-	long zap_work = ZAP_BLOCK_SIZE;
 	unsigned long start = start_addr;
-	struct mutex *i_mmap_mutex = details ? details->i_mmap_mutex : NULL;
 	struct mm_struct *mm = vma->vm_mm;
 
 	mmu_notifier_invalidate_range_start(mm, start_addr, end_addr);
@@ -1238,33 +1223,16 @@ unsigned long unmap_vmas(struct mmu_gath
 				 * Since no pte has actually been setup, it is
 				 * safe to do nothing in this case.
 				 */
-				if (vma->vm_file) {
+				if (vma->vm_file)
 					unmap_hugepage_range(vma, start, end, NULL);
-					zap_work -= (end - start) /
-					pages_per_huge_page(hstate_vma(vma));
-				}
 
 				start = end;
 			} else
 				start = unmap_page_range(tlb, vma,
-						start, end, &zap_work, details);
-
-			if (zap_work > 0) {
-				BUG_ON(start != end);
-				break;
-			}
-
-			if (need_resched() ||
-				(i_mmap_mutex && mutex_is_contended(i_mmap_mutex))) {
-				if (i_mmap_mutex)
-					goto out;
-				cond_resched();
-			}
-
-			zap_work = ZAP_BLOCK_SIZE;
+						start, end, details);
 		}
 	}
-out:
+
 	mmu_notifier_invalidate_range_end(mm, start_addr, end_addr);
 	return start;	/* which is now the end (or restart) address */
 }
@@ -2528,96 +2496,11 @@ static int do_wp_page(struct mm_struct *
 	return ret;
 }
 
-/*
- * Helper functions for unmap_mapping_range().
- *
- * __ Notes on dropping i_mmap_mutex to reduce latency while unmapping __
- *
- * We have to restart searching the prio_tree whenever we drop the lock,
- * since the iterator is only valid while the lock is held, and anyway
- * a later vma might be split and reinserted earlier while lock dropped.
- *
- * The list of nonlinear vmas could be handled more efficiently, using
- * a placeholder, but handle it in the same way until a need is shown.
- * It is important to search the prio_tree before nonlinear list: a vma
- * may become nonlinear and be shifted from prio_tree to nonlinear list
- * while the lock is dropped; but never shifted from list to prio_tree.
- *
- * In order to make forward progress despite restarting the search,
- * vm_truncate_count is used to mark a vma as now dealt with, so we can
- * quickly skip it next time around.  Since the prio_tree search only
- * shows us those vmas affected by unmapping the range in question, we
- * can't efficiently keep all vmas in step with mapping->truncate_count:
- * so instead reset them all whenever it wraps back to 0 (then go to 1).
- * mapping->truncate_count and vma->vm_truncate_count are protected by
- * i_mmap_mutex.
- *
- * In order to make forward progress despite repeatedly restarting some
- * large vma, note the restart_addr from unmap_vmas when it breaks out:
- * and restart from that address when we reach that vma again.  It might
- * have been split or merged, shrunk or extended, but never shifted: so
- * restart_addr remains valid so long as it remains in the vma's range.
- * unmap_mapping_range forces truncate_count to leap over page-aligned
- * values so we can save vma's restart_addr in its truncate_count field.
- */
-#define is_restart_addr(truncate_count) (!((truncate_count) & ~PAGE_MASK))
-
-static void reset_vma_truncate_counts(struct address_space *mapping)
-{
-	struct vm_area_struct *vma;
-	struct prio_tree_iter iter;
-
-	vma_prio_tree_foreach(vma, &iter, &mapping->i_mmap, 0, ULONG_MAX)
-		vma->vm_truncate_count = 0;
-	list_for_each_entry(vma, &mapping->i_mmap_nonlinear, shared.vm_set.list)
-		vma->vm_truncate_count = 0;
-}
-
-static int unmap_mapping_range_vma(struct vm_area_struct *vma,
+static void unmap_mapping_range_vma(struct vm_area_struct *vma,
 		unsigned long start_addr, unsigned long end_addr,
 		struct zap_details *details)
 {
-	unsigned long restart_addr;
-	int need_break;
-
-	/*
-	 * files that support invalidating or truncating portions of the
-	 * file from under mmaped areas must have their ->fault function
-	 * return a locked page (and set VM_FAULT_LOCKED in the return).
-	 * This provides synchronisation against concurrent unmapping here.
-	 */
-
-again:
-	restart_addr = vma->vm_truncate_count;
-	if (is_restart_addr(restart_addr) && start_addr < restart_addr) {
-		start_addr = restart_addr;
-		if (start_addr >= end_addr) {
-			/* Top of vma has been split off since last time */
-			vma->vm_truncate_count = details->truncate_count;
-			return 0;
-		}
-	}
-
-	restart_addr = zap_page_range(vma, start_addr,
-					end_addr - start_addr, details);
-	need_break = need_resched() || mutex_is_contended(details->i_mmap_mutex);
-
-	if (restart_addr >= end_addr) {
-		/* We have now completed this vma: mark it so */
-		vma->vm_truncate_count = details->truncate_count;
-		if (!need_break)
-			return 0;
-	} else {
-		/* Note restart_addr in vma's truncate_count field */
-		vma->vm_truncate_count = restart_addr;
-		if (!need_break)
-			goto again;
-	}
-
-	mutex_unlock(details->i_mmap_mutex);
-	cond_resched();
-	mutex_lock(details->i_mmap_mutex);
-	return -EINTR;
+	zap_page_range(vma, start_addr, end_addr - start_addr, details);
 }
 
 static inline void unmap_mapping_range_tree(struct prio_tree_root *root,
@@ -2627,12 +2510,8 @@ static inline void unmap_mapping_range_t
 	struct prio_tree_iter iter;
 	pgoff_t vba, vea, zba, zea;
 
-restart:
 	vma_prio_tree_foreach(vma, &iter, root,
 			details->first_index, details->last_index) {
-		/* Skip quickly over those we have already dealt with */
-		if (vma->vm_truncate_count == details->truncate_count)
-			continue;
 
 		vba = vma->vm_pgoff;
 		vea = vba + ((vma->vm_end - vma->vm_start) >> PAGE_SHIFT) - 1;
@@ -2644,11 +2523,10 @@ static inline void unmap_mapping_range_t
 		if (zea > vea)
 			zea = vea;
 
-		if (unmap_mapping_range_vma(vma,
+		unmap_mapping_range_vma(vma,
 			((zba - vba) << PAGE_SHIFT) + vma->vm_start,
 			((zea - vba + 1) << PAGE_SHIFT) + vma->vm_start,
-				details) < 0)
-			goto restart;
+				details);
 	}
 }
 
@@ -2663,15 +2541,9 @@ static inline void unmap_mapping_range_l
 	 * across *all* the pages in each nonlinear VMA, not just the pages
 	 * whose virtual address lies outside the file truncation point.
 	 */
-restart:
 	list_for_each_entry(vma, head, shared.vm_set.list) {
-		/* Skip quickly over those we have already dealt with */
-		if (vma->vm_truncate_count == details->truncate_count)
-			continue;
 		details->nonlinear_vma = vma;
-		if (unmap_mapping_range_vma(vma, vma->vm_start,
-					vma->vm_end, details) < 0)
-			goto restart;
+		unmap_mapping_range_vma(vma, vma->vm_start, vma->vm_end, details);
 	}
 }
 
@@ -2710,19 +2582,8 @@ void unmap_mapping_range(struct address_
 	details.last_index = hba + hlen - 1;
 	if (details.last_index < details.first_index)
 		details.last_index = ULONG_MAX;
-	details.i_mmap_mutex = &mapping->i_mmap_mutex;
 
 	mutex_lock(&mapping->i_mmap_mutex);
-
-	/* Protect against endless unmapping loops */
-	mapping->truncate_count++;
-	if (unlikely(is_restart_addr(mapping->truncate_count))) {
-		if (mapping->truncate_count == 0)
-			reset_vma_truncate_counts(mapping);
-		mapping->truncate_count++;
-	}
-	details.truncate_count = mapping->truncate_count;
-
 	if (unlikely(!prio_tree_empty(&mapping->i_mmap)))
 		unmap_mapping_range_tree(&mapping->i_mmap, &details);
 	if (unlikely(!list_empty(&mapping->i_mmap_nonlinear)))
Index: linux-2.6/include/linux/fs.h
===================================================================
--- linux-2.6.orig/include/linux/fs.h
+++ linux-2.6/include/linux/fs.h
@@ -640,7 +640,6 @@ struct address_space {
 	struct prio_tree_root	i_mmap;		/* tree of private and shared mappings */
 	struct list_head	i_mmap_nonlinear;/*list VM_NONLINEAR mappings */
 	struct mutex		i_mmap_mutex;	/* protect tree, count, list */
-	unsigned int		truncate_count;	/* Cover race condition with truncate */
 	unsigned long		nrpages;	/* number of total pages */
 	pgoff_t			writeback_index;/* writeback starts here */
 	const struct address_space_operations *a_ops;	/* methods */
Index: linux-2.6/include/linux/mm_types.h
===================================================================
--- linux-2.6.orig/include/linux/mm_types.h
+++ linux-2.6/include/linux/mm_types.h
@@ -175,7 +175,6 @@ struct vm_area_struct {
 					   units, *not* PAGE_CACHE_SIZE */
 	struct file * vm_file;		/* File we map to (can be NULL). */
 	void * vm_private_data;		/* was vm_pte (shared mem) */
-	unsigned long vm_truncate_count;/* truncate_count or restart_addr */
 
 #ifndef CONFIG_MMU
 	struct vm_region *vm_region;	/* NOMMU mapping region */
Index: linux-2.6/kernel/fork.c
===================================================================
--- linux-2.6.orig/kernel/fork.c
+++ linux-2.6/kernel/fork.c
@@ -379,7 +379,6 @@ static int dup_mmap(struct mm_struct *mm
 			mutex_lock(&mapping->i_mmap_mutex);
 			if (tmp->vm_flags & VM_SHARED)
 				mapping->i_mmap_writable++;
-			tmp->vm_truncate_count = mpnt->vm_truncate_count;
 			flush_dcache_mmap_lock(mapping);
 			/* insert tmp into the share list, just after mpnt */
 			vma_prio_tree_add(tmp, mpnt);
Index: linux-2.6/mm/mmap.c
===================================================================
--- linux-2.6.orig/mm/mmap.c
+++ linux-2.6/mm/mmap.c
@@ -464,10 +464,8 @@ static void vma_link(struct mm_struct *m
 	if (vma->vm_file)
 		mapping = vma->vm_file->f_mapping;
 
-	if (mapping) {
+	if (mapping)
 		mutex_lock(&mapping->i_mmap_mutex);
-		vma->vm_truncate_count = mapping->truncate_count;
-	}
 
 	__vma_link(mm, vma, prev, rb_link, rb_parent);
 	__vma_link_file(vma);
@@ -577,16 +575,7 @@ again:			remove_next = 1 + (end > next->
 		if (!(vma->vm_flags & VM_NONLINEAR))
 			root = &mapping->i_mmap;
 		mutex_lock(&mapping->i_mmap_mutex);
-		if (importer &&
-		    vma->vm_truncate_count != next->vm_truncate_count) {
-			/*
-			 * unmap_mapping_range might be in progress:
-			 * ensure that the expanding vma is rescanned.
-			 */
-			importer->vm_truncate_count = 0;
-		}
 		if (insert) {
-			insert->vm_truncate_count = vma->vm_truncate_count;
 			/*
 			 * Put into prio_tree now, so instantiated pages
 			 * are visible to arm/parisc __flush_dcache_page
Index: linux-2.6/mm/mremap.c
===================================================================
--- linux-2.6.orig/mm/mremap.c
+++ linux-2.6/mm/mremap.c
@@ -94,9 +94,6 @@ static void move_ptes(struct vm_area_str
 		 */
 		mapping = vma->vm_file->f_mapping;
 		mutex_lock(&mapping->i_mmap_mutex);
-		if (new_vma->vm_truncate_count &&
-		    new_vma->vm_truncate_count != vma->vm_truncate_count)
-			new_vma->vm_truncate_count = 0;
 	}
 
 	/*


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[PATCH 25/25] mm, arch: Ensure we never tlb_flush_mmu() from atomic context

[Peter Zijlstra]

[-- Attachment #1: mm-flush-vs-pte_lock.patch --]
[-- Type: text/plain, Size: 10661 bytes --]

Hugh noted that we could still end up flushing the batch from atomic
context because we do tlb_remove_page() while holding the pte_lock.

This will still generate immense latencies, more so now than ever
before due to the larger batches. Break tlb_remove_page() into two
functions, one that queues the page and one that flushes the queue.

Leave the tlb_remove_page() interface for now with the old semantics
but add a might_sleep() in there to detect callers from atomic
contexts.

XXX should probably fold back into the mmu_gather preempt patches for
the various architectures.

Reported-by: Hugh Dickins <hughd@google.com>
Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/arm/include/asm/tlb.h  |   17 ++++++++++++++++-
 arch/ia64/include/asm/tlb.h |   22 ++++++++++++++++++----
 arch/s390/include/asm/tlb.h |   18 ++++++++++++------
 arch/sh/include/asm/tlb.h   |   17 ++++++++++++++++-
 arch/um/include/asm/tlb.h   |   15 +++++++++++----
 include/asm-generic/tlb.h   |   22 +++++++++++++++-------
 mm/memory.c                 |   14 +++++++++++---
 7 files changed, 99 insertions(+), 26 deletions(-)

Index: linux-2.6/include/asm-generic/tlb.h
===================================================================
--- linux-2.6.orig/include/asm-generic/tlb.h
+++ linux-2.6/include/asm-generic/tlb.h
@@ -146,7 +146,7 @@ tlb_gather_mmu(struct mmu_gather *tlb, s
 }
 
 static inline void
-tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
+tlb_flush_mmu(struct mmu_gather *tlb)
 {
 	struct mmu_gather_batch *batch;
 
@@ -176,7 +176,7 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
 {
 	struct mmu_gather_batch *batch, *next;
 
-	tlb_flush_mmu(tlb, start, end);
+	tlb_flush_mmu(tlb);
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
@@ -193,7 +193,7 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
  *	handling the additional races in SMP caused by other CPUs caching valid
  *	mappings in their TLBs.
  */
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
 	struct mmu_gather_batch *batch;
 
@@ -201,17 +201,25 @@ static inline void tlb_remove_page(struc
 
 	if (tlb_fast_mode(tlb)) {
 		free_page_and_swap_cache(page);
-		return;
+		return 0;
 	}
 
 	batch = tlb->active;
+	batch->pages[batch->nr++] = page;
 	if (batch->nr == batch->max) {
 		if (!tlb_next_batch(tlb))
-			tlb_flush_mmu(tlb, 0, 0);
-		batch = tlb->active;
+			return 1;
 	}
 
-	batch->pages[batch->nr++] = page;
+	return 0;
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	might_sleep();
+
+	if (__tlb_remove_page(tlb, page))
+		tlb_flush_mmu(tlb);
 }
 
 /**
Index: linux-2.6/mm/memory.c
===================================================================
--- linux-2.6.orig/mm/memory.c
+++ linux-2.6/mm/memory.c
@@ -990,11 +990,12 @@ static unsigned long zap_pte_range(struc
 {
 	struct mm_struct *mm = tlb->mm;
 	int rss[NR_MM_COUNTERS];
+	int need_flush = 0;
 	spinlock_t *ptl;
 	pte_t *pte;
 
 	init_rss_vec(rss);
-
+again:
 	pte = pte_offset_map_lock(mm, pmd, addr, &ptl);
 	arch_enter_lazy_mmu_mode();
 	do {
@@ -1048,7 +1049,7 @@ static unsigned long zap_pte_range(struc
 			page_remove_rmap(page);
 			if (unlikely(page_mapcount(page) < 0))
 				print_bad_pte(vma, addr, ptent, page);
-			tlb_remove_page(tlb, page);
+			need_flush = __tlb_remove_page(tlb, page);
 			continue;
 		}
 		/*
@@ -1069,12 +1070,19 @@ static unsigned long zap_pte_range(struc
 				print_bad_pte(vma, addr, ptent, NULL);
 		}
 		pte_clear_not_present_full(mm, addr, pte, tlb->fullmm);
-	} while (pte++, addr += PAGE_SIZE, addr != end);
+	} while (pte++, addr += PAGE_SIZE, (addr != end && !need_flush));
 
 	add_mm_rss_vec(mm, rss);
 	arch_leave_lazy_mmu_mode();
 	pte_unmap_unlock(pte - 1, ptl);
 
+	if (need_flush) {
+		need_flush = 0;
+		tlb_flush_mmu(tlb);
+		if (addr != end)
+			goto again;
+	}
+
 	return addr;
 }
 
Index: linux-2.6/arch/arm/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/arm/include/asm/tlb.h
+++ linux-2.6/arch/arm/include/asm/tlb.h
@@ -93,7 +93,22 @@ tlb_end_vma(struct mmu_gather *tlb, stru
 		flush_tlb_range(vma, tlb->range_start, tlb->range_end);
 }
 
-#define tlb_remove_page(tlb,page)	free_page_and_swap_cache(page)
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	free_page_and_swap_cache(page);
+	return 0;
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	might_sleep();
+	__tlb_remove_page(tlb, page);
+}
+
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+}
+
 #define pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
 #define pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
 
Index: linux-2.6/arch/ia64/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/ia64/include/asm/tlb.h
+++ linux-2.6/arch/ia64/include/asm/tlb.h
@@ -204,14 +204,13 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
  * must be delayed until after the TLB has been flushed (see comments at the beginning of
  * this file).
  */
-static inline void
-tlb_remove_page (struct mmu_gather *tlb, struct page *page)
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
 	tlb->need_flush = 1;
 
 	if (tlb_fast_mode(tlb)) {
 		free_page_and_swap_cache(page);
-		return;
+		return 0;
 	}
 
 	if (!tlb->nr && tlb->pages == tlb->local)
@@ -219,7 +218,22 @@ tlb_remove_page (struct mmu_gather *tlb,
 
 	tlb->pages[tlb->nr++] = page;
 	if (tlb->nr >= tlb->max)
-		ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
+		return 1;
+
+	return 0;
+}
+
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+	ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	might_sleep();
+
+	if (__tlb_remove_page(tlb, page))
+		tlb_flush_mmu(tlb);
 }
 
 /*
Index: linux-2.6/arch/s390/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/s390/include/asm/tlb.h
+++ linux-2.6/arch/s390/include/asm/tlb.h
@@ -64,8 +64,7 @@ static inline void tlb_gather_mmu(struct
 	tlb->nr_pxds = tlb->max;
 }
 
-static inline void tlb_flush_mmu(struct mmu_gather *tlb,
-				 unsigned long start, unsigned long end)
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
 {
 	if (!tlb->fullmm && (tlb->nr_ptes > 0 || tlb->nr_pxds < tlb->max))
 		__tlb_flush_mm(tlb->mm);
@@ -78,7 +77,7 @@ static inline void tlb_flush_mmu(struct 
 static inline void tlb_finish_mmu(struct mmu_gather *tlb,
 				  unsigned long start, unsigned long end)
 {
-	tlb_flush_mmu(tlb, start, end);
+	tlb_flush_mmu(tlb);
 
 	rcu_table_freelist_finish();
 
@@ -94,8 +93,15 @@ static inline void tlb_finish_mmu(struct
  * tlb_ptep_clear_flush. In both flush modes the tlb fo a page cache page
  * has already been freed, so just do free_page_and_swap_cache.
  */
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	free_page_and_swap_cache(page);
+	return 0;
+}
+
 static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
+	might_sleep();
 	free_page_and_swap_cache(page);
 }
 
@@ -109,7 +115,7 @@ static inline void pte_free_tlb(struct m
 	if (!tlb->fullmm) {
 		tlb->array[tlb->nr_ptes++] = pte;
 		if (tlb->nr_ptes >= tlb->nr_pxds)
-			tlb_flush_mmu(tlb, 0, 0);
+			tlb_flush_mmu(tlb);
 	} else
 		page_table_free(tlb->mm, (unsigned long *) pte);
 }
@@ -130,7 +136,7 @@ static inline void pmd_free_tlb(struct m
 	if (!tlb->fullmm) {
 		tlb->array[--tlb->nr_pxds] = pmd;
 		if (tlb->nr_ptes >= tlb->nr_pxds)
-			tlb_flush_mmu(tlb, 0, 0);
+			tlb_flush_mmu(tlb);
 	} else
 		crst_table_free(tlb->mm, (unsigned long *) pmd);
 #endif
@@ -152,7 +158,7 @@ static inline void pud_free_tlb(struct m
 	if (!tlb->fullmm) {
 		tlb->array[--tlb->nr_pxds] = pud;
 		if (tlb->nr_ptes >= tlb->nr_pxds)
-			tlb_flush_mmu(tlb, 0, 0);
+			tlb_flush_mmu(tlb);
 	} else
 		crst_table_free(tlb->mm, (unsigned long *) pud);
 #endif
Index: linux-2.6/arch/sh/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/sh/include/asm/tlb.h
+++ linux-2.6/arch/sh/include/asm/tlb.h
@@ -83,7 +83,22 @@ tlb_end_vma(struct mmu_gather *tlb, stru
 	}
 }
 
-#define tlb_remove_page(tlb,page)	free_page_and_swap_cache(page)
+static inline void tlb_flush_mmu(struct mmu_gather *tlb)
+{
+}
+
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	free_page_and_swap_cache(page);
+	return 0;
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	might_sleep();
+	__tlb_remove_page(tlb, page);
+}
+
 #define pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
 #define pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
 #define pud_free_tlb(tlb, pudp, addr)	pud_free((tlb)->mm, pudp)
Index: linux-2.6/arch/um/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/um/include/asm/tlb.h
+++ linux-2.6/arch/um/include/asm/tlb.h
@@ -57,7 +57,7 @@ extern void flush_tlb_mm_range(struct mm
 			       unsigned long end);
 
 static inline void
-tlb_flush_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
+tlb_flush_mmu(struct mmu_gather *tlb)
 {
 	if (!tlb->need_flush)
 		return;
@@ -73,7 +73,7 @@ tlb_flush_mmu(struct mmu_gather *tlb, un
 static inline void
 tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
-	tlb_flush_mmu(tlb, start, end);
+	tlb_flush_mmu(tlb);
 
 	/* keep the page table cache within bounds */
 	check_pgt_cache();
@@ -84,11 +84,18 @@ tlb_finish_mmu(struct mmu_gather *tlb, u
  *	while handling the additional races in SMP caused by other CPUs
  *	caching valid mappings in their TLBs.
  */
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
 {
 	tlb->need_flush = 1;
 	free_page_and_swap_cache(page);
-	return;
+	return 0;
+}
+
+static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
+{
+	might_sleep();
+
+	__tlb_remove_page(tlb, page);
 }
 
 /**


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Re: [PATCH 00/25] mm: Preemptibility -v7

[Sam Ravnborg]

On Tue, Jan 25, 2011 at 06:31:11PM +0100, Peter Zijlstra wrote:
> 
> This patch-set makes part of the mm a lot more preemptible. It converts
> i_mmap_lock and anon_vma->lock to mutexes and makes mmu_gather fully
> preemptible.
> 
> The main motivation was making mm_take_all_locks() preemptible, since it
> appears people are nesting hundreds of spinlocks there.
> 
> The side-effects are that can finally make mmu_gather preemptible,
> something which lots of people have wanted to do for a long time.
> 
> It also gets us anon_vma refcounting, which seems to result in a nice
> cleanup of the anon_vma lifetime rules wrt KSM and compaction.
> 
> This patch-set is build and boot-tested on x86_64 (a previous version was
> also tested on Dave's Niagra2 machines, and I suppose s390 was too when
> Martin provided the conversion patch for his arch).
> 
> There are no known architectures left unconverted.

Hi Peter.

Foregive me my ignorance..
Why is this relevant for sparc64 but not for sparc32?

A quick grep showed up only this in sparc32 specific files:

mm/init_32.c:DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);

Maybe this is just something sparc32 does not support?

	Sam

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Peter Zijlstra]

On Tue, 2011-01-25 at 19:32 +0100, Sam Ravnborg wrote:

> Foregive me my ignorance..
> Why is this relevant for sparc64 but not for sparc32?
> 
> A quick grep showed up only this in sparc32 specific files:
> 
> mm/init_32.c:DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
> 
> Maybe this is just something sparc32 does not support?

sparc32 uses include/asm-generic/tlb.h, whereas sparc64 implements its
own variant.

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Sam Ravnborg]

On Tue, Jan 25, 2011 at 08:28:53PM +0100, Peter Zijlstra wrote:
> On Tue, 2011-01-25 at 19:32 +0100, Sam Ravnborg wrote:
> 
> > Foregive me my ignorance..
> > Why is this relevant for sparc64 but not for sparc32?
> > 
> > A quick grep showed up only this in sparc32 specific files:
> > 
> > mm/init_32.c:DEFINE_PER_CPU(struct mmu_gather, mmu_gathers);
> > 
> > Maybe this is just something sparc32 does not support?
> 
> sparc32 uses include/asm-generic/tlb.h, whereas sparc64 implements its
> own variant.

Ahh, thanks!

	Sam

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Andi Kleen]

Peter Zijlstra <a.p.zijlstra@chello.nl> writes:

> This patch-set makes part of the mm a lot more preemptible. It converts
> i_mmap_lock and anon_vma->lock to mutexes and makes mmu_gather fully
> preemptible.
>
> The main motivation was making mm_take_all_locks() preemptible, since it
> appears people are nesting hundreds of spinlocks there.

Just curious: why is mm_take_all_locks() a problem? As far as I can see
it's just used when starting KVM or GRU the first time. Is that a common
situation?

-Andi

-- 
Andi Kleen
Intel Open Source Technology Center

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Andi Kleen]

> Its nesting hundreds of spinlocks (255+) make the preempt debug code
> unhappy, it also causes fun latencies when you do start KVM/GRU
> Although arguably that's the least convincing reason to do all this its
> the one that got me to actually compose this series -- I really should
> write a new leader..
Least Convincing is a good description...
Tuning operations which only happen once is not very interesting, 
especially if that affects
fast paths.

> Making all this preemptible also allows making the whole mmu_gather
> thing preemptible, which is something we've wanted to do for a long
> while, it also allows XPMEM or whatever that thing was called (Andrea
> knows) and of course, it moves a part of -rt upstream.

I thought the reason for the preempt off inside the mmu gather region was
to stay on the same CPU for local/remote flushes. How would it change that?

> If we decide to keep patch 24, it also simplifies the truncate path
> quite a bit.
That sounds like a good thing. Making truncate simpler is always good.

-Andi

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Peter Zijlstra]

On Tue, 2011-01-25 at 12:47 -0800, Andi Kleen wrote:
> 
> I thought the reason for the preempt off inside the mmu gather region was
> to stay on the same CPU for local/remote flushes. How would it change that? 

afaik its been preempt-off solely because it was always inside a number
of spinlocks, I know both Hugh and BenH worked on making it preemptible
far before I started this.

I remember Hugh and Nick talking about this at OLS'06 or 07, can't
really remember.

As to local/remote flushes, there is no real saying where the pages came
from due to on-demand paging and the scheduler never having had a notion
of home-node. Therefore freeing them wouldn't be more of less local if
that is exposed to the same migration as allocation was.


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[RFC][PATCH 26/25] mm, arch: Convert ia64, arm, sh to generic tlb

[Peter Zijlstra]

I was looking at what makes the various arches use !generic tlb gather
bits and found that for most the reason is the same, so I looked at what
it would take to support those in the generic code as well.

The below is a quick unification, I still need to run through all the
details since they appear to all do the same thing but slightly
different ;-)

I've compile tested it on ia64 and arm (seem to have lost my SH compiler
again).

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
---
 arch/Kconfig                    |    3 
 arch/arm/Kconfig                |    1 
 arch/arm/include/asm/tlb.h      |   90 --------------------
 arch/arm/include/asm/tlbflush.h |    5 -
 arch/ia64/Kconfig               |    1 
 arch/ia64/include/asm/tlb.h     |  178 +---------------------------------------
 arch/sh/Kconfig                 |    1 
 arch/sh/include/asm/tlb.h       |   99 +---------------------
 include/asm-generic/tlb.h       |   35 +++++++
 9 files changed, 59 insertions(+), 354 deletions(-)

Index: linux-2.6/arch/Kconfig
===================================================================
--- linux-2.6.orig/arch/Kconfig
+++ linux-2.6/arch/Kconfig
@@ -181,4 +181,7 @@ config HAVE_ARCH_MUTEX_CPU_RELAX
 config HAVE_RCU_TABLE_FREE
 	bool
 
+config HAVE_MMU_GATHER_RANGE
+	bool
+
 source "kernel/gcov/Kconfig"
Index: linux-2.6/arch/arm/Kconfig
===================================================================
--- linux-2.6.orig/arch/arm/Kconfig
+++ linux-2.6/arch/arm/Kconfig
@@ -28,6 +28,7 @@ config ARM
 	select HAVE_C_RECORDMCOUNT
 	select HAVE_GENERIC_HARDIRQS
 	select HAVE_SPARSE_IRQ
+	select HAVE_MMU_GATHER_RANGE if MMU
 	help
 	  The ARM series is a line of low-power-consumption RISC chip designs
 	  licensed by ARM Ltd and targeted at embedded applications and
Index: linux-2.6/arch/arm/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/arm/include/asm/tlb.h
+++ linux-2.6/arch/arm/include/asm/tlb.h
@@ -23,96 +23,14 @@
 #ifndef CONFIG_MMU
 
 #include <linux/pagemap.h>
-#include <asm-generic/tlb.h>
 
 #else /* !CONFIG_MMU */
 
-#include <asm/pgalloc.h>
-
-/*
- * TLB handling.  This allows us to remove pages from the page
- * tables, and efficiently handle the TLB issues.
- */
-struct mmu_gather {
-	struct mm_struct	*mm;
-	unsigned int		fullmm;
-	unsigned long		range_start;
-	unsigned long		range_end;
-};
-
-static inline void
-tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
-{
-	tlb->mm = mm;
-	tlb->fullmm = full_mm_flush;
-}
-
-static inline void
-tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
-{
-	if (tlb->fullmm)
-		flush_tlb_mm(tlb->mm);
-
-	/* keep the page table cache within bounds */
-	check_pgt_cache();
-}
-
-/*
- * Memorize the range for the TLB flush.
- */
-static inline void
-tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long addr)
-{
-	if (!tlb->fullmm) {
-		if (addr < tlb->range_start)
-			tlb->range_start = addr;
-		if (addr + PAGE_SIZE > tlb->range_end)
-			tlb->range_end = addr + PAGE_SIZE;
-	}
-}
-
-/*
- * In the case of tlb vma handling, we can optimise these away in the
- * case where we're doing a full MM flush.  When we're doing a munmap,
- * the vmas are adjusted to only cover the region to be torn down.
- */
-static inline void
-tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
-	if (!tlb->fullmm) {
-		flush_cache_range(vma, vma->vm_start, vma->vm_end);
-		tlb->range_start = TASK_SIZE;
-		tlb->range_end = 0;
-	}
-}
-
-static inline void
-tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
-	if (!tlb->fullmm && tlb->range_end > 0)
-		flush_tlb_range(vma, tlb->range_start, tlb->range_end);
-}
-
-static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	free_page_and_swap_cache(page);
-	return 0;
-}
-
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	might_sleep();
-	__tlb_remove_page(tlb, page);
-}
-
-static inline void tlb_flush_mmu(struct mmu_gather *tlb)
-{
-}
+#define __pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
+#define __pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
 
-#define pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
-#define pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
+#endif /* CONFIG_MMU */
 
-#define tlb_migrate_finish(mm)		do { } while (0)
+#include <asm-generic/tlb.h>
 
-#endif /* CONFIG_MMU */
 #endif
Index: linux-2.6/arch/ia64/Kconfig
===================================================================
--- linux-2.6.orig/arch/ia64/Kconfig
+++ linux-2.6/arch/ia64/Kconfig
@@ -25,6 +25,7 @@ config IA64
 	select HAVE_GENERIC_HARDIRQS
 	select GENERIC_IRQ_PROBE
 	select GENERIC_PENDING_IRQ if SMP
+	select HAVE_MMU_GATHER_RANGE
 	select IRQ_PER_CPU
 	default y
 	help
Index: linux-2.6/arch/ia64/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/ia64/include/asm/tlb.h
+++ linux-2.6/arch/ia64/include/asm/tlb.h
@@ -46,30 +46,6 @@
 #include <asm/tlbflush.h>
 #include <asm/machvec.h>
 
-#ifdef CONFIG_SMP
-# define tlb_fast_mode(tlb)	((tlb)->nr == ~0U)
-#else
-# define tlb_fast_mode(tlb)	(1)
-#endif
-
-/*
- * If we can't allocate a page to make a big batch of page pointers
- * to work on, then just handle a few from the on-stack structure.
- */
-#define	IA64_GATHER_BUNDLE	8
-
-struct mmu_gather {
-	struct mm_struct	*mm;
-	unsigned int		nr;		/* == ~0U => fast mode */
-	unsigned int		max;
-	unsigned char		fullmm;		/* non-zero means full mm flush */
-	unsigned char		need_flush;	/* really unmapped some PTEs? */
-	unsigned long		start_addr;
-	unsigned long		end_addr;
-	struct page		**pages;
-	struct page		*local[IA64_GATHER_BUNDLE];
-};
-
 struct ia64_tr_entry {
 	u64 ifa;
 	u64 itir;
@@ -96,6 +72,12 @@ extern struct ia64_tr_entry *ia64_idtrs[
 #define RR_RID_MASK	0x00000000ffffff00L
 #define RR_TO_RID(val) 	((val >> 8) & 0xffffff)
 
+static inline void tlb_flush(struct mmu_gather *tlb);
+
+#define tlb_migrate_finish(mm)	platform_tlb_migrate_finish(mm)
+
+#include <asm-generic/tlb.h>
+
 /*
  * Flush the TLB for address range START to END and, if not in fast mode, release the
  * freed pages that where gathered up to this point.
@@ -103,12 +85,6 @@ extern struct ia64_tr_entry *ia64_idtrs[
 static inline void
 ia64_tlb_flush_mmu (struct mmu_gather *tlb, unsigned long start, unsigned long end)
 {
-	unsigned int nr;
-
-	if (!tlb->need_flush)
-		return;
-	tlb->need_flush = 0;
-
 	if (tlb->fullmm) {
 		/*
 		 * Tearing down the entire address space.  This happens both as a result
@@ -138,149 +114,11 @@ ia64_tlb_flush_mmu (struct mmu_gather *t
 		/* now flush the virt. page-table area mapping the address range: */
 		flush_tlb_range(&vma, ia64_thash(start), ia64_thash(end));
 	}
-
-	/* lastly, release the freed pages */
-	nr = tlb->nr;
-	if (!tlb_fast_mode(tlb)) {
-		unsigned long i;
-		tlb->nr = 0;
-		tlb->start_addr = ~0UL;
-		for (i = 0; i < nr; ++i)
-			free_page_and_swap_cache(tlb->pages[i]);
-	}
-}
-
-static inline void __tlb_alloc_page(struct mmu_gather *tlb)
-{
-	unsigned long addr = __get_free_pages(GFP_NOWAIT | __GFP_NOWARN, 0);
-
-	if (addr) {
-		tlb->pages = (void *)addr;
-		tlb->max = PAGE_SIZE / sizeof(void *);
-	}
-}
-
-
-static inline void
-tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
-{
-	tlb->mm = mm;
-	tlb->max = ARRAY_SIZE(tlb->local);
-	tlb->pages = tlb->local;
-	/*
-	 * Use fast mode if only 1 CPU is online.
-	 *
-	 * It would be tempting to turn on fast-mode for full_mm_flush as well.  But this
-	 * doesn't work because of speculative accesses and software prefetching: the page
-	 * table of "mm" may (and usually is) the currently active page table and even
-	 * though the kernel won't do any user-space accesses during the TLB shoot down, a
-	 * compiler might use speculation or lfetch.fault on what happens to be a valid
-	 * user-space address.  This in turn could trigger a TLB miss fault (or a VHPT
-	 * walk) and re-insert a TLB entry we just removed.  Slow mode avoids such
-	 * problems.  (We could make fast-mode work by switching the current task to a
-	 * different "mm" during the shootdown.) --davidm 08/02/2002
-	 */
-	tlb->nr = (num_online_cpus() == 1) ? ~0U : 0;
-	tlb->fullmm = full_mm_flush;
-	tlb->start_addr = ~0UL;
 }
 
-/*
- * Called at the end of the shootdown operation to free up any resources that were
- * collected.
- */
-static inline void
-tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
+static inline void tlb_flush(struct mmu_gather *tlb)
 {
-	/*
-	 * Note: tlb->nr may be 0 at this point, so we can't rely on tlb->start_addr and
-	 * tlb->end_addr.
-	 */
-	ia64_tlb_flush_mmu(tlb, start, end);
-
-	/* keep the page table cache within bounds */
-	check_pgt_cache();
-
-	if (tlb->pages != tlb->local)
-		free_pages((unsigned long)tlb->pages, 0);
+	ia64_tlb_flush_mmu(tlb, tlb->start, tlb->end);
 }
 
-/*
- * Logically, this routine frees PAGE.  On MP machines, the actual freeing of the page
- * must be delayed until after the TLB has been flushed (see comments at the beginning of
- * this file).
- */
-static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	tlb->need_flush = 1;
-
-	if (tlb_fast_mode(tlb)) {
-		free_page_and_swap_cache(page);
-		return 0;
-	}
-
-	if (!tlb->nr && tlb->pages == tlb->local)
-		__tlb_alloc_page(tlb);
-
-	tlb->pages[tlb->nr++] = page;
-	if (tlb->nr >= tlb->max)
-		return 1;
-
-	return 0;
-}
-
-static inline void tlb_flush_mmu(struct mmu_gather *tlb)
-{
-	ia64_tlb_flush_mmu(tlb, tlb->start_addr, tlb->end_addr);
-}
-
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	might_sleep();
-
-	if (__tlb_remove_page(tlb, page))
-		tlb_flush_mmu(tlb);
-}
-
-/*
- * Remove TLB entry for PTE mapped at virtual address ADDRESS.  This is called for any
- * PTE, not just those pointing to (normal) physical memory.
- */
-static inline void
-__tlb_remove_tlb_entry (struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
-{
-	if (tlb->start_addr == ~0UL)
-		tlb->start_addr = address;
-	tlb->end_addr = address + PAGE_SIZE;
-}
-
-#define tlb_migrate_finish(mm)	platform_tlb_migrate_finish(mm)
-
-#define tlb_start_vma(tlb, vma)			do { } while (0)
-#define tlb_end_vma(tlb, vma)			do { } while (0)
-
-#define tlb_remove_tlb_entry(tlb, ptep, addr)		\
-do {							\
-	tlb->need_flush = 1;				\
-	__tlb_remove_tlb_entry(tlb, ptep, addr);	\
-} while (0)
-
-#define pte_free_tlb(tlb, ptep, address)		\
-do {							\
-	tlb->need_flush = 1;				\
-	__pte_free_tlb(tlb, ptep, address);		\
-} while (0)
-
-#define pmd_free_tlb(tlb, ptep, address)		\
-do {							\
-	tlb->need_flush = 1;				\
-	__pmd_free_tlb(tlb, ptep, address);		\
-} while (0)
-
-#define pud_free_tlb(tlb, pudp, address)		\
-do {							\
-	tlb->need_flush = 1;				\
-	__pud_free_tlb(tlb, pudp, address);		\
-} while (0)
-
 #endif /* _ASM_IA64_TLB_H */
Index: linux-2.6/arch/sh/Kconfig
===================================================================
--- linux-2.6.orig/arch/sh/Kconfig
+++ linux-2.6/arch/sh/Kconfig
@@ -22,6 +22,7 @@ config SUPERH
 	select HAVE_SPARSE_IRQ
 	select RTC_LIB
 	select GENERIC_ATOMIC64
+	select HAVE_MMU_GATHER_RANGE if MMU
 	# Support the deprecated APIs until MFD and GPIOLIB catch up.
 	select GENERIC_HARDIRQS_NO_DEPRECATED if !MFD_SUPPORT && !GPIOLIB
 	help
Index: linux-2.6/arch/sh/include/asm/tlb.h
===================================================================
--- linux-2.6.orig/arch/sh/include/asm/tlb.h
+++ linux-2.6/arch/sh/include/asm/tlb.h
@@ -9,101 +9,11 @@
 #include <linux/pagemap.h>
 
 #ifdef CONFIG_MMU
-#include <asm/pgalloc.h>
-#include <asm/tlbflush.h>
 #include <asm/mmu_context.h>
 
-/*
- * TLB handling.  This allows us to remove pages from the page
- * tables, and efficiently handle the TLB issues.
- */
-struct mmu_gather {
-	struct mm_struct	*mm;
-	unsigned int		fullmm;
-	unsigned long		start, end;
-};
-
-static inline void init_tlb_gather(struct mmu_gather *tlb)
-{
-	tlb->start = TASK_SIZE;
-	tlb->end = 0;
-
-	if (tlb->fullmm) {
-		tlb->start = 0;
-		tlb->end = TASK_SIZE;
-	}
-}
-
-static inline void
-tlb_gather_mmu(struct mmu_gather *tlb, struct mm_struct *mm, unsigned int full_mm_flush)
-{
-	tlb->mm = mm;
-	tlb->fullmm = full_mm_flush;
-
-	init_tlb_gather(tlb);
-}
-
-static inline void
-tlb_finish_mmu(struct mmu_gather *tlb, unsigned long start, unsigned long end)
-{
-	if (tlb->fullmm)
-		flush_tlb_mm(tlb->mm);
-
-	/* keep the page table cache within bounds */
-	check_pgt_cache();
-}
-
-static inline void
-tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
-{
-	if (tlb->start > address)
-		tlb->start = address;
-	if (tlb->end < address + PAGE_SIZE)
-		tlb->end = address + PAGE_SIZE;
-}
-
-/*
- * In the case of tlb vma handling, we can optimise these away in the
- * case where we're doing a full MM flush.  When we're doing a munmap,
- * the vmas are adjusted to only cover the region to be torn down.
- */
-static inline void
-tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
-	if (!tlb->fullmm)
-		flush_cache_range(vma, vma->vm_start, vma->vm_end);
-}
-
-static inline void
-tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
-{
-	if (!tlb->fullmm && tlb->end) {
-		flush_tlb_range(vma, tlb->start, tlb->end);
-		init_tlb_gather(tlb);
-	}
-}
-
-static inline void tlb_flush_mmu(struct mmu_gather *tlb)
-{
-}
-
-static inline int __tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	free_page_and_swap_cache(page);
-	return 0;
-}
-
-static inline void tlb_remove_page(struct mmu_gather *tlb, struct page *page)
-{
-	might_sleep();
-	__tlb_remove_page(tlb, page);
-}
-
-#define pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
-#define pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
-#define pud_free_tlb(tlb, pudp, addr)	pud_free((tlb)->mm, pudp)
-
-#define tlb_migrate_finish(mm)		do { } while (0)
+#define __pte_free_tlb(tlb, ptep, addr)	pte_free((tlb)->mm, ptep)
+#define __pmd_free_tlb(tlb, pmdp, addr)	pmd_free((tlb)->mm, pmdp)
+#define __pud_free_tlb(tlb, pudp, addr)	pud_free((tlb)->mm, pudp)
 
 #if defined(CONFIG_CPU_SH4) || defined(CONFIG_SUPERH64)
 extern void tlb_wire_entry(struct vm_area_struct *, unsigned long, pte_t);
@@ -128,8 +38,9 @@ static inline void tlb_unwire_entry(void
 #define __tlb_remove_tlb_entry(tlb, pte, address)	do { } while (0)
 #define tlb_flush(tlb)					do { } while (0)
 
+#endif /* CONFIG_MMU */
+
 #include <asm-generic/tlb.h>
 
-#endif /* CONFIG_MMU */
 #endif /* __ASSEMBLY__ */
 #endif /* __ASM_SH_TLB_H */
Index: linux-2.6/include/asm-generic/tlb.h
===================================================================
--- linux-2.6.orig/include/asm-generic/tlb.h
+++ linux-2.6/include/asm-generic/tlb.h
@@ -79,6 +79,10 @@ struct mmu_gather {
 				fast_mode  : 1; /* No batching   */
 	unsigned int		fullmm;		/* Flush full mm */
 
+#ifdef CONFIG_HAVE_MMU_GATHER_RANGE
+	unsigned long		start, end;
+#endif
+
 	struct mmu_gather_batch *active;
 	struct mmu_gather_batch	local;
 	struct page		*__pages[8];
@@ -222,6 +226,35 @@ static inline void tlb_remove_page(struc
 		tlb_flush_mmu(tlb);
 }
 
+#ifdef CONFIG_HAVE_MMU_GATHER_RANGE
+static inline void
+__tlb_remove_tlb_entry(struct mmu_gather *tlb, pte_t *ptep, unsigned long address)
+{
+	if (!tlb->fullmm) {
+		tlb->start = min(tlb->start, address);
+		address += PAGE_SIZE;
+		tlb->end = max(tlb->end, address);
+	}
+}
+
+static inline void
+tlb_start_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+	if (!tlb->fullmm) {
+		flush_cache_range(vma, vma->vm_start, vma->vm_end);
+		tlb->start = TASK_SIZE;
+		tlb->end = 0;
+	}
+}
+
+static inline void
+tlb_end_vma(struct mmu_gather *tlb, struct vm_area_struct *vma)
+{
+	if (!tlb->fullmm && tlb->end)
+		flush_tlb_range(vma, tlb->start, tlb->end);
+}
+#endif
+
 /**
  * tlb_remove_tlb_entry - remember a pte unmapping for later tlb invalidation.
  *
@@ -255,6 +288,8 @@ static inline void tlb_remove_page(struc
 		__pmd_free_tlb(tlb, pmdp, address);		\
 	} while (0)
 
+#ifndef tlb_migrate_finish
 #define tlb_migrate_finish(mm) do {} while (0)
+#endif
 
 #endif /* _ASM_GENERIC__TLB_H */
Index: linux-2.6/arch/arm/include/asm/tlbflush.h
===================================================================
--- linux-2.6.orig/arch/arm/include/asm/tlbflush.h
+++ linux-2.6/arch/arm/include/asm/tlbflush.h
@@ -10,12 +10,9 @@
 #ifndef _ASMARM_TLBFLUSH_H
 #define _ASMARM_TLBFLUSH_H
 
-
-#ifndef CONFIG_MMU
-
 #define tlb_flush(tlb)	((void) tlb)
 
-#else /* CONFIG_MMU */
+#ifdef CONFIG_MMU
 
 #include <asm/glue.h>
 

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Re: [PATCH 00/25] mm: Preemptibility -v7

[Peter Zijlstra]

On Tue, 2011-01-25 at 18:31 +0100, Peter Zijlstra wrote:
>  - figure out what to do with sparc's tlb_batch lack of ->fullmm

David, how does this look?

---
Index: linux-2.6/arch/sparc/mm/tlb.c
===================================================================
--- linux-2.6.orig/arch/sparc/mm/tlb.c
+++ linux-2.6/arch/sparc/mm/tlb.c
@@ -43,7 +43,8 @@ void flush_tlb_pending(void)
 	put_cpu_var(tlb_batch);
 }
 
-void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr, pte_t *ptep, pte_t orig)
+void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr, 
+		   pte_t *ptep, pte_t orig, int fullmm)
 {
 	struct tlb_batch *tb = &get_cpu_var(tlb_batch);
 	unsigned long nr;
@@ -77,12 +78,10 @@ void tlb_batch_add(struct mm_struct *mm,
 
 no_cache_flush:
 
-	/*
-	if (tb->fullmm) {
+	if (fullmm) {
 		put_cpu_var(tlb_batch);
 		return;
 	}
-	*/
 
 	nr = tb->tlb_nr;
 
Index: linux-2.6/arch/sparc/include/asm/pgtable_64.h
===================================================================
--- linux-2.6.orig/arch/sparc/include/asm/pgtable_64.h
+++ linux-2.6/arch/sparc/include/asm/pgtable_64.h
@@ -655,9 +655,11 @@ static inline int pte_special(pte_t pte)
 #define pte_unmap(pte)			do { } while (0)
 
 /* Actual page table PTE updates.  */
-extern void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr, pte_t *ptep, pte_t orig);
+extern void tlb_batch_add(struct mm_struct *mm, unsigned long vaddr, 
+			  pte_t *ptep, pte_t orig, int fullmm);
 
-static inline void set_pte_at(struct mm_struct *mm, unsigned long addr, pte_t *ptep, pte_t pte)
+static inline void __set_pte_at(struct mm_struct *mm, unsigned long addr, 
+			     pte_t *ptep, pte_t pte, int fullmm)
 {
 	pte_t orig = *ptep;
 
@@ -670,12 +672,19 @@ static inline void set_pte_at(struct mm_
 	 *             and SUN4V pte layout, so this inline test is fine.
 	 */
 	if (likely(mm != &init_mm) && (pte_val(orig) & _PAGE_VALID))
-		tlb_batch_add(mm, addr, ptep, orig);
+		tlb_batch_add(mm, addr, ptep, orig, fullmm);
 }
 
+#define set_pte_at(mm,addr,ptep,pte)	\
+	__set_pte_at((mm), (addr), (ptep), (pte), 0)
+
 #define pte_clear(mm,addr,ptep)		\
 	set_pte_at((mm), (addr), (ptep), __pte(0UL))
 
+#define __HAVE_ARCH_PTE_CLEAR_NOT_PRESENT_FULL
+#define pte_clear_not_present_full(mm,addr,ptep,fullmm)	\
+	__set_pte_at((mm), (addr), (ptep), __pte(0UL), (fullmm))
+
 #ifdef DCACHE_ALIASING_POSSIBLE
 #define __HAVE_ARCH_MOVE_PTE
 #define move_pte(pte, prot, old_addr, new_addr)				\

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