Kill off hugepage_vma()

Kill off hugepage_vma()

[David Gibson]

Kenneth, does the patch below look reasonable?  It's close to trivial
on everything except IA64, which I can't easily test on.  Actually, it
occurs to me that this may even fix a bug on IA64 - if follow_page()
was called on an address in region 1 that wasn't in a VMA, then I
think it would attempt to follow it as a normal page, which sounds
bad.

If you think it is sane, I intend to push to akpm.

hugepage_vma() is both misleadingly named and unnecessary.  On most
archs it always returns NULL, and on IA64 the vma it returns is never
used.  The function's real purpose is to determine whether the address
it is passed is a special hugepage address which must be looked up in
hugepage pagetables, rather than being looked up in the normal
pagetables (which might have specially marked hugepage PMDs or PTEs).

This patch kills off hugepage_vma() and folds the logic it really
needs into follow_huge_addr().  That now returns a (page *) if called
on a special hugepage address, and an error encoded with ERR_PTR
otherwise.  This also requires tweaking the IA64 code to check that
the hugepage PTE is present in follow_huge_addr() - previously this
was guaranteed, since it was only called if the address was in an
existing hugepage VMA, and hugepages are always prefaulted.

Index: working-2.6/include/linux/hugetlb.h
===================================================================
--- working-2.6.orig/include/linux/hugetlb.h	2004-04-13 11:42:41.000000000 +1000
+++ working-2.6/include/linux/hugetlb.h	2004-04-16 15:33:18.113820400 +1000
@@ -20,10 +20,8 @@
 int hugetlb_report_meminfo(char *);
 int is_hugepage_mem_enough(size_t);
 unsigned long hugetlb_total_pages(void);
-struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma,
-			unsigned long address, int write);
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm,
-					unsigned long address);
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address,
+			      int write);
 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 				pmd_t *pmd, int write);
 int is_aligned_hugepage_range(unsigned long addr, unsigned long len);
@@ -65,7 +63,7 @@
 }
 
 #define follow_hugetlb_page(m,v,p,vs,a,b,i)	({ BUG(); 0; })
-#define follow_huge_addr(mm, vma, addr, write)	0
+#define follow_huge_addr(mm, addr, write)	ERR_PTR(-EINVAL)
 #define copy_hugetlb_page_range(src, dst, vma)	({ BUG(); 0; })
 #define hugetlb_prefault(mapping, vma)		({ BUG(); 0; })
 #define zap_hugepage_range(vma, start, len)	BUG()
@@ -73,7 +71,6 @@
 #define huge_page_release(page)			BUG()
 #define is_hugepage_mem_enough(size)		0
 #define hugetlb_report_meminfo(buf)		0
-#define hugepage_vma(mm, addr)			0
 #define mark_mm_hugetlb(mm, vma)		do { } while (0)
 #define follow_huge_pmd(mm, addr, pmd, write)	0
 #define is_aligned_hugepage_range(addr, len)	0
Index: working-2.6/mm/memory.c
===================================================================
--- working-2.6.orig/mm/memory.c	2004-04-13 11:42:42.000000000 +1000
+++ working-2.6/mm/memory.c	2004-04-16 15:32:59.170904152 +1000
@@ -629,11 +629,11 @@
 	pmd_t *pmd;
 	pte_t *ptep, pte;
 	unsigned long pfn;
-	struct vm_area_struct *vma;
+	struct page *page;
 
-	vma = hugepage_vma(mm, address);
-	if (vma)
-		return follow_huge_addr(mm, vma, address, write);
+	page = follow_huge_addr(mm, address, write);
+	if (! IS_ERR(page))
+		return page;
 
 	pgd = pgd_offset(mm, address);
 	if (pgd_none(*pgd) || pgd_bad(*pgd))
Index: working-2.6/arch/ppc64/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/ppc64/mm/hugetlbpage.c	2004-04-16 15:26:41.000000000 +1000
+++ working-2.6/arch/ppc64/mm/hugetlbpage.c	2004-04-16 15:34:27.000000000 +1000
@@ -335,15 +335,9 @@
 }
 
 struct page *
-follow_huge_addr(struct mm_struct *mm,
-	struct vm_area_struct *vma, unsigned long address, int write)
+follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 {
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
+	return ERR_PTR(-EINVAL);
 }
 
 int pmd_huge(pmd_t pmd)
Index: working-2.6/arch/i386/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/i386/mm/hugetlbpage.c	2004-04-16 15:26:37.000000000 +1000
+++ working-2.6/arch/i386/mm/hugetlbpage.c	2004-04-16 15:39:55.000000000 +1000
@@ -140,32 +140,31 @@
 
 #if 0	/* This is just for testing */
 struct page *
-follow_huge_addr(struct mm_struct *mm,
-	struct vm_area_struct *vma, unsigned long address, int write)
+follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 {
 	unsigned long start = address;
 	int length = 1;
 	int nr;
 	struct page *page;
+	struct vm_area_struct *vma;
 
-	nr = follow_hugetlb_page(mm, vma, &page, NULL, &start, &length, 0);
-	if (nr == 1)
-		return page;
-	return NULL;
-}
+	if (! mm->used_hugetlb)
+		return ERR_PTR(-EINVAL);
 
-/*
- * If virtual address `addr' lies within a huge page, return its controlling
- * VMA, else NULL.
- */
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	if (mm->used_hugetlb) {
-		struct vm_area_struct *vma = find_vma(mm, addr);
-		if (vma && is_vm_hugetlb_page(vma))
-			return vma;
-	}
-	return NULL;
+	vma = find_vma(mm, addr);
+	if (!vma || !is_vm_hugetlb_page(vma))
+		return ERR_PTR(-EINVAL);
+
+	pte = huge_pte_offset(mm, address);
+
+	/* hugetlb should be locked, and hence, prefaulted */
+	WARN_ON(!pte || pte_none(*pte));
+
+	page = &pte_page(*pte)[vpfn % (HPAGE_SIZE/PAGE_SIZE)];
+
+	WARN_ON(!PageCompound(page));
+
+	return page;
 }
 
 int pmd_huge(pmd_t pmd)
@@ -183,15 +182,9 @@
 #else
 
 struct page *
-follow_huge_addr(struct mm_struct *mm,
-	struct vm_area_struct *vma, unsigned long address, int write)
+follow_huge_addr(struct mm_struct *mm, unsigned long address, int write)
 {
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
+	return ERR_PTR(-EINVAL);
 }
 
 int pmd_huge(pmd_t pmd)
Index: working-2.6/arch/ia64/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/ia64/mm/hugetlbpage.c	2004-04-16 15:26:37.000000000 +1000
+++ working-2.6/arch/ia64/mm/hugetlbpage.c	2004-04-16 15:43:06.000000000 +1000
@@ -49,8 +49,12 @@
 	pte_t *pte = NULL;
 
 	pgd = pgd_offset(mm, taddr);
-	pmd = pmd_offset(pgd, taddr);
-	pte = pte_offset_map(pmd, taddr);
+	if (pgd_present(*pgd)) {
+		pmd = pmd_offset(pgd, taddr);
+		if (pmd_present(*pmd))
+			pte = pte_offset_map(pmd, taddr);
+	}
+
 	return pte;
 }
 
@@ -150,24 +154,19 @@
 	return i;
 }
 
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	if (mm->used_hugetlb) {
-		if (REGION_NUMBER(addr) == REGION_HPAGE) {
-			struct vm_area_struct *vma = find_vma(mm, addr);
-			if (vma && is_vm_hugetlb_page(vma))
-				return vma;
-		}
-	}
-	return NULL;
-}
-
-struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, int write)
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int write)
 {
 	struct page *page;
 	pte_t *ptep;
 
+	if (! mm->used_hugetlb)
+		return ERR_PTR(-EINVAL);
+	if (REGION_NUMBER(addr) != REGION_HPAGE)
+		return ERR_PTR(-EINVAL);
+
 	ptep = huge_pte_offset(mm, addr);
+	if (!ptep || pte_none(*ptep))
+		return NULL;
 	page = pte_page(*ptep);
 	page += ((addr & ~HPAGE_MASK) >> PAGE_SHIFT);
 	return page;
Index: working-2.6/arch/sparc64/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/sparc64/mm/hugetlbpage.c	2004-04-16 10:43:02.000000000 +1000
+++ working-2.6/arch/sparc64/mm/hugetlbpage.c	2004-04-16 15:48:36.000000000 +1000
@@ -164,15 +164,9 @@
 }
 
 struct page *follow_huge_addr(struct mm_struct *mm,
-			      struct vm_area_struct *vma,
 			      unsigned long address, int write)
 {
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
+	return ERR_PTR(-EINVAL);
 }
 
 int pmd_huge(pmd_t pmd)
Index: working-2.6/arch/sh/mm/hugetlbpage.c
===================================================================
--- working-2.6.orig/arch/sh/mm/hugetlbpage.c	2004-04-13 11:42:35.000000000 +1000
+++ working-2.6/arch/sh/mm/hugetlbpage.c	2004-04-16 15:48:31.000000000 +1000
@@ -166,15 +166,9 @@
 }
 
 struct page *follow_huge_addr(struct mm_struct *mm,
-			      struct vm_area_struct *vma,
 			      unsigned long address, int write)
 {
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
+	return ERR_PTR(-EINVAL);
 }
 
 int pmd_huge(pmd_t pmd)



-- 
David Gibson			| For every complex problem there is a
david AT gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson

RE: Kill off hugepage_vma()

[Chen, Kenneth W]

Original post on LKML:
http://www.ussg.iu.edu/hypermail/linux/kernel/0404.2/0017.html

>>>> David Gibson wrote on Thursday, April 15, 2004 11:22 PM
> Kenneth, does the patch below look reasonable?  It's close to trivial
> on everything except IA64, which I can't easily test on.  Actually, it
> occurs to me that this may even fix a bug on IA64 - if follow_page()
> was called on an address in region 1 that wasn't in a VMA, then I
> think it would attempt to follow it as a normal page, which sounds
> bad.

Thanks to well written code in the caller of follow_page(), that they
always call find_extend_vma() to make sure address belongs to a vma
before calling down to follow_page().  So there is no bug here.

Minor FYI: on ia64, huge page address is in region 4.


> hugepage_vma() is both misleadingly named and unnecessary.  On most
> archs it always returns NULL, and on IA64 the vma it returns is never
> used.  The function's real purpose is to determine whether the address
> it is passed is a special hugepage address which must be looked up in
> hugepage pagetables, rather than being looked up in the normal
> pagetables (which might have specially marked hugepage PMDs or PTEs).


One way or the other, the check has to be there.  If the name is vague,
a new name can be proposed.


> This patch kills off hugepage_vma() and folds the logic it really
> needs into follow_huge_addr().  That now returns a (page *) if called
> on a special hugepage address, and an error encoded with ERR_PTR
> otherwise.  This also requires tweaking the IA64 code to check that
> the hugepage PTE is present in follow_huge_addr() - previously this
> was guaranteed, since it was only called if the address was in an
> existing hugepage VMA, and hugepages are always prefaulted.

Why not do one step further? Instead of call a dummy function that
always return false, why not stub it out in the header file for arch
that don't need follow_huge_addr? This would speedup everyone.

I propose the following patch:


diff -Nur linux-2.6.5/arch/i386/mm/hugetlbpage.c linux-2.6.5.htlb/arch/i386/mm/hugetlbpage.c
--- linux-2.6.5/arch/i386/mm/hugetlbpage.c	2004-04-16 13:23:22.000000000 -0700
+++ linux-2.6.5.htlb/arch/i386/mm/hugetlbpage.c	2004-04-16 14:15:28.000000000 -0700
@@ -182,18 +182,6 @@

 #else

-struct page *
-follow_huge_addr(struct mm_struct *mm,
-	struct vm_area_struct *vma, unsigned long address, int write)
-{
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
-}
-
 int pmd_huge(pmd_t pmd)
 {
 	return !!(pmd_val(pmd) & _PAGE_PSE);
diff -Nur linux-2.6.5/arch/ia64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/ia64/mm/hugetlbpage.c
--- linux-2.6.5/arch/ia64/mm/hugetlbpage.c	2004-04-16 13:23:22.000000000 -0700
+++ linux-2.6.5.htlb/arch/ia64/mm/hugetlbpage.c	2004-04-16 14:20:35.000000000 -0700
@@ -149,19 +149,7 @@
 	return i;
 }

-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	if (mm->used_hugetlb) {
-		if (REGION_NUMBER(addr) == REGION_HPAGE) {
-			struct vm_area_struct *vma = find_vma(mm, addr);
-			if (vma && is_vm_hugetlb_page(vma))
-				return vma;
-		}
-	}
-	return NULL;
-}
-
-struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, int write)
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int write)
 {
 	struct page *page;
 	pte_t *ptep;
diff -Nur linux-2.6.5/arch/ppc64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/ppc64/mm/hugetlbpage.c
--- linux-2.6.5/arch/ppc64/mm/hugetlbpage.c	2004-04-16 13:23:22.000000000 -0700
+++ linux-2.6.5.htlb/arch/ppc64/mm/hugetlbpage.c	2004-04-16 14:37:19.000000000 -0700
@@ -334,18 +334,6 @@
 	return i;
 }

-struct page *
-follow_huge_addr(struct mm_struct *mm,
-	struct vm_area_struct *vma, unsigned long address, int write)
-{
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
-}
-
 int pmd_huge(pmd_t pmd)
 {
 	return pmd_hugepage(pmd);
diff -Nur linux-2.6.5/arch/sh/mm/hugetlbpage.c linux-2.6.5.htlb/arch/sh/mm/hugetlbpage.c
--- linux-2.6.5/arch/sh/mm/hugetlbpage.c	2004-04-16 13:23:22.000000000 -0700
+++ linux-2.6.5.htlb/arch/sh/mm/hugetlbpage.c	2004-04-16 14:16:09.000000000 -0700
@@ -165,18 +165,6 @@
 	return i;
 }

-struct page *follow_huge_addr(struct mm_struct *mm,
-			      struct vm_area_struct *vma,
-			      unsigned long address, int write)
-{
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
-}
-
 int pmd_huge(pmd_t pmd)
 {
 	return 0;
diff -Nur linux-2.6.5/arch/sparc64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/sparc64/mm/hugetlbpage.c
--- linux-2.6.5/arch/sparc64/mm/hugetlbpage.c	2004-04-16 13:23:22.000000000 -0700
+++ linux-2.6.5.htlb/arch/sparc64/mm/hugetlbpage.c	2004-04-16 14:16:24.000000000 -0700
@@ -162,18 +162,6 @@
 	return i;
 }

-struct page *follow_huge_addr(struct mm_struct *mm,
-			      struct vm_area_struct *vma,
-			      unsigned long address, int write)
-{
-	return NULL;
-}
-
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
-{
-	return NULL;
-}
-
 int pmd_huge(pmd_t pmd)
 {
 	return 0;
diff -Nur linux-2.6.5/include/asm-ia64/page.h linux-2.6.5.htlb/include/asm-ia64/page.h
--- linux-2.6.5/include/asm-ia64/page.h	2004-04-03 19:36:19.000000000 -0800
+++ linux-2.6.5.htlb/include/asm-ia64/page.h	2004-04-16 14:07:52.000000000 -0700
@@ -47,6 +47,7 @@

 # define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
 # define ARCH_HAS_HUGEPAGE_ONLY_RANGE
+# define ARCH_HAS_FOLLOW_HUGE_ADDR
 #endif /* CONFIG_HUGETLB_PAGE */

 #ifdef __ASSEMBLY__
@@ -123,6 +124,7 @@
 # define is_hugepage_only_range(addr, len)		\
 	 (REGION_NUMBER(addr) == REGION_HPAGE &&	\
 	  REGION_NUMBER((addr)+(len)) == REGION_HPAGE)
+# define prepare_follow_huge_addr(addr)	(REGION_NUMBER(addr) == REGION_HPAGE)
 extern unsigned int hpage_shift;
 #endif

diff -Nur linux-2.6.5/include/linux/hugetlb.h linux-2.6.5.htlb/include/linux/hugetlb.h
--- linux-2.6.5/include/linux/hugetlb.h	2004-04-16 13:23:25.000000000 -0700
+++ linux-2.6.5.htlb/include/linux/hugetlb.h	2004-04-16 14:14:16.000000000 -0700
@@ -22,10 +22,6 @@
 int hugetlb_report_meminfo(char *);
 int is_hugepage_mem_enough(size_t);
 unsigned long hugetlb_total_pages(void);
-struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma,
-			unsigned long address, int write);
-struct vm_area_struct *hugepage_vma(struct mm_struct *mm,
-					unsigned long address);
 struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
 				pmd_t *pmd, int write);
 int is_aligned_hugepage_range(unsigned long addr, unsigned long len);
@@ -55,6 +51,13 @@
 int prepare_hugepage_range(unsigned long addr, unsigned long len);
 #endif

+#ifndef ARCH_HAS_FOLLOW_HUGE_ADDR
+#define prepare_follow_huge_addr(addr)		0
+#define follow_huge_addr(mm, addr, write)	0
+#else
+struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write);
+#endif
+
 #else /* !CONFIG_HUGETLB_PAGE */

 static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
@@ -67,7 +70,8 @@
 }

 #define follow_hugetlb_page(m,v,p,vs,a,b,i)	({ BUG(); 0; })
-#define follow_huge_addr(mm, vma, addr, write)	0
+#define prepare_follow_huge_addr(addr)		0
+#define follow_huge_addr(mm, addr, write)	0
 #define copy_hugetlb_page_range(src, dst, vma)	({ BUG(); 0; })
 #define hugetlb_prefault(mapping, vma)		({ BUG(); 0; })
 #define zap_hugepage_range(vma, start, len)	BUG()
@@ -75,7 +79,6 @@
 #define huge_page_release(page)			BUG()
 #define is_hugepage_mem_enough(size)		0
 #define hugetlb_report_meminfo(buf)		0
-#define hugepage_vma(mm, addr)			0
 #define mark_mm_hugetlb(mm, vma)		do { } while (0)
 #define follow_huge_pmd(mm, addr, pmd, write)	0
 #define is_aligned_hugepage_range(addr, len)	0
diff -Nur linux-2.6.5/mm/memory.c linux-2.6.5.htlb/mm/memory.c
--- linux-2.6.5/mm/memory.c	2004-04-16 13:23:25.000000000 -0700
+++ linux-2.6.5.htlb/mm/memory.c	2004-04-16 14:20:49.000000000 -0700
@@ -629,11 +629,9 @@
 	pmd_t *pmd;
 	pte_t *ptep, pte;
 	unsigned long pfn;
-	struct vm_area_struct *vma;

-	vma = hugepage_vma(mm, address);
-	if (vma)
-		return follow_huge_addr(mm, vma, address, write);
+	if (prepare_follow_huge_addr(address))
+		return follow_huge_addr(mm, address, write);

 	pgd = pgd_offset(mm, address);
 	if (pgd_none(*pgd) || pgd_bad(*pgd))

Re: Kill off hugepage_vma()

['David Gibson']

On Fri, Apr 16, 2004 at 03:14:39PM -0700, Chen, Kenneth W wrote:
> Original post on LKML:
> http://www.ussg.iu.edu/hypermail/linux/kernel/0404.2/0017.html
> 
> >>>> David Gibson wrote on Thursday, April 15, 2004 11:22 PM
> > Kenneth, does the patch below look reasonable?  It's close to trivial
> > on everything except IA64, which I can't easily test on.  Actually, it
> > occurs to me that this may even fix a bug on IA64 - if follow_page()
> > was called on an address in region 1 that wasn't in a VMA, then I
> > think it would attempt to follow it as a normal page, which sounds
> > bad.
> 
> Thanks to well written code in the caller of follow_page(), that they
> always call find_extend_vma() to make sure address belongs to a vma
> before calling down to follow_page().  So there is no bug here.

Ah, good point.

> Minor FYI: on ia64, huge page address is in region 4.

Oops.

> > hugepage_vma() is both misleadingly named and unnecessary.  On most
> > archs it always returns NULL, and on IA64 the vma it returns is never
> > used.  The function's real purpose is to determine whether the address
> > it is passed is a special hugepage address which must be looked up in
> > hugepage pagetables, rather than being looked up in the normal
> > pagetables (which might have specially marked hugepage PMDs or PTEs).
> 
> One way or the other, the check has to be there.  If the name is vague,
> a new name can be proposed.
> 
> > This patch kills off hugepage_vma() and folds the logic it really
> > needs into follow_huge_addr().  That now returns a (page *) if called
> > on a special hugepage address, and an error encoded with ERR_PTR
> > otherwise.  This also requires tweaking the IA64 code to check that
> > the hugepage PTE is present in follow_huge_addr() - previously this
> > was guaranteed, since it was only called if the address was in an
> > existing hugepage VMA, and hugepages are always prefaulted.
> 
> Why not do one step further? Instead of call a dummy function that
> always return false, why not stub it out in the header file for arch
> that don't need follow_huge_addr? This would speedup everyone.

I didn't do that purely to avoid proliferating more ARCH_HAS_BLAH
defines (we already have 2 for hugepage).  It has no more overhead
than the current version of course.  I have no strong preference on
this point.

However, I folded the check logic into hugetlb_follow_addr() rather
than leaving it as two functions for a reason - akpm indicated that he
thought the former was preferable.  I like that approach slightly
better myself, too, although it's not a strong preference.

If it were to be two functions though, I really dislike the name
prepare_follow_huge_addr().  I'd prefer, say, in_hugepage_region().

> I propose the following patch:
> 
> 
> diff -Nur linux-2.6.5/arch/i386/mm/hugetlbpage.c linux-2.6.5.htlb/arch/i386/mm/hugetlbpage.c
> +++ linux-2.6.5.htlb/arch/i386/mm/hugetlbpage.c	2004-04-16 14:15:28.000000000 -0700
> @@ -182,18 +182,6 @@
> 
>  #else
> 
> -struct page *
> -follow_huge_addr(struct mm_struct *mm,
> -	struct vm_area_struct *vma, unsigned long address, int write)
> -{
> -	return NULL;
> -}
> -
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
> -{
> -	return NULL;
> -}
> -
>  int pmd_huge(pmd_t pmd)
>  {
>  	return !!(pmd_val(pmd) & _PAGE_PSE);
> diff -Nur linux-2.6.5/arch/ia64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/ia64/mm/hugetlbpage.c
> +++ linux-2.6.5.htlb/arch/ia64/mm/hugetlbpage.c	2004-04-16 14:20:35.000000000 -0700
> @@ -149,19 +149,7 @@
>  	return i;
>  }
> 
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
> -{
> -	if (mm->used_hugetlb) {
> -		if (REGION_NUMBER(addr) == REGION_HPAGE) {
> -			struct vm_area_struct *vma = find_vma(mm, addr);
> -			if (vma && is_vm_hugetlb_page(vma))
> -				return vma;
> -		}
> -	}
> -	return NULL;
> -}
> -
> -struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma, unsigned long addr, int write)
> +struct page *follow_huge_addr(struct mm_struct *mm, unsigned long addr, int write)
>  {
>  	struct page *page;
>  	pte_t *ptep;
> diff -Nur linux-2.6.5/arch/ppc64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/ppc64/mm/hugetlbpage.c
> +++ linux-2.6.5.htlb/arch/ppc64/mm/hugetlbpage.c	2004-04-16 14:37:19.000000000 -0700
> @@ -334,18 +334,6 @@
>  	return i;
>  }
> 
> -struct page *
> -follow_huge_addr(struct mm_struct *mm,
> -	struct vm_area_struct *vma, unsigned long address, int write)
> -{
> -	return NULL;
> -}
> -
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
> -{
> -	return NULL;
> -}
> -
>  int pmd_huge(pmd_t pmd)
>  {
>  	return pmd_hugepage(pmd);
> diff -Nur linux-2.6.5/arch/sh/mm/hugetlbpage.c linux-2.6.5.htlb/arch/sh/mm/hugetlbpage.c
> +++ linux-2.6.5.htlb/arch/sh/mm/hugetlbpage.c	2004-04-16 14:16:09.000000000 -0700
> @@ -165,18 +165,6 @@
>  	return i;
>  }
> 
> -struct page *follow_huge_addr(struct mm_struct *mm,
> -			      struct vm_area_struct *vma,
> -			      unsigned long address, int write)
> -{
> -	return NULL;
> -}
> -
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
> -{
> -	return NULL;
> -}
> -
>  int pmd_huge(pmd_t pmd)
>  {
>  	return 0;
> diff -Nur linux-2.6.5/arch/sparc64/mm/hugetlbpage.c linux-2.6.5.htlb/arch/sparc64/mm/hugetlbpage.c
> +++ linux-2.6.5.htlb/arch/sparc64/mm/hugetlbpage.c	2004-04-16 14:16:24.000000000 -0700
> @@ -162,18 +162,6 @@
>  	return i;
>  }
> 
> -struct page *follow_huge_addr(struct mm_struct *mm,
> -			      struct vm_area_struct *vma,
> -			      unsigned long address, int write)
> -{
> -	return NULL;
> -}
> -
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm, unsigned long addr)
> -{
> -	return NULL;
> -}
> -
>  int pmd_huge(pmd_t pmd)
>  {
>  	return 0;
> diff -Nur linux-2.6.5/include/asm-ia64/page.h linux-2.6.5.htlb/include/asm-ia64/page.h
> +++ linux-2.6.5.htlb/include/asm-ia64/page.h	2004-04-16 14:07:52.000000000 -0700
> @@ -47,6 +47,7 @@
> 
>  # define HAVE_ARCH_HUGETLB_UNMAPPED_AREA
>  # define ARCH_HAS_HUGEPAGE_ONLY_RANGE
> +# define ARCH_HAS_FOLLOW_HUGE_ADDR
>  #endif /* CONFIG_HUGETLB_PAGE */
> 
>  #ifdef __ASSEMBLY__
> @@ -123,6 +124,7 @@
>  # define is_hugepage_only_range(addr, len)		\
>  	 (REGION_NUMBER(addr) == REGION_HPAGE &&	\
>  	  REGION_NUMBER((addr)+(len)) == REGION_HPAGE)
> +# define prepare_follow_huge_addr(addr)	(REGION_NUMBER(addr) == REGION_HPAGE)
>  extern unsigned int hpage_shift;
>  #endif
> 
> diff -Nur linux-2.6.5/include/linux/hugetlb.h linux-2.6.5.htlb/include/linux/hugetlb.h
> +++ linux-2.6.5.htlb/include/linux/hugetlb.h	2004-04-16 14:14:16.000000000 -0700
> @@ -22,10 +22,6 @@
>  int hugetlb_report_meminfo(char *);
>  int is_hugepage_mem_enough(size_t);
>  unsigned long hugetlb_total_pages(void);
> -struct page *follow_huge_addr(struct mm_struct *mm, struct vm_area_struct *vma,
> -			unsigned long address, int write);
> -struct vm_area_struct *hugepage_vma(struct mm_struct *mm,
> -					unsigned long address);
>  struct page *follow_huge_pmd(struct mm_struct *mm, unsigned long address,
>  				pmd_t *pmd, int write);
>  int is_aligned_hugepage_range(unsigned long addr, unsigned long len);
> @@ -55,6 +51,13 @@
>  int prepare_hugepage_range(unsigned long addr, unsigned long len);
>  #endif
> 
> +#ifndef ARCH_HAS_FOLLOW_HUGE_ADDR
> +#define prepare_follow_huge_addr(addr)		0
> +#define follow_huge_addr(mm, addr, write)	0
> +#else
> +struct page *follow_huge_addr(struct mm_struct *mm, unsigned long address, int write);
> +#endif
> +
>  #else /* !CONFIG_HUGETLB_PAGE */
> 
>  static inline int is_vm_hugetlb_page(struct vm_area_struct *vma)
> @@ -67,7 +70,8 @@
>  }
> 
>  #define follow_hugetlb_page(m,v,p,vs,a,b,i)	({ BUG(); 0; })
> -#define follow_huge_addr(mm, vma, addr, write)	0
> +#define prepare_follow_huge_addr(addr)		0
> +#define follow_huge_addr(mm, addr, write)	0
>  #define copy_hugetlb_page_range(src, dst, vma)	({ BUG(); 0; })
>  #define hugetlb_prefault(mapping, vma)		({ BUG(); 0; })
>  #define zap_hugepage_range(vma, start, len)	BUG()
> @@ -75,7 +79,6 @@
>  #define huge_page_release(page)			BUG()
>  #define is_hugepage_mem_enough(size)		0
>  #define hugetlb_report_meminfo(buf)		0
> -#define hugepage_vma(mm, addr)			0
>  #define mark_mm_hugetlb(mm, vma)		do { } while (0)
>  #define follow_huge_pmd(mm, addr, pmd, write)	0
>  #define is_aligned_hugepage_range(addr, len)	0
> diff -Nur linux-2.6.5/mm/memory.c linux-2.6.5.htlb/mm/memory.c
> +++ linux-2.6.5.htlb/mm/memory.c	2004-04-16 14:20:49.000000000 -0700
> @@ -629,11 +629,9 @@
>  	pmd_t *pmd;
>  	pte_t *ptep, pte;
>  	unsigned long pfn;
> -	struct vm_area_struct *vma;
> 
> -	vma = hugepage_vma(mm, address);
> -	if (vma)
> -		return follow_huge_addr(mm, vma, address, write);
> +	if (prepare_follow_huge_addr(address))
> +		return follow_huge_addr(mm, address, write);
> 
>  	pgd = pgd_offset(mm, address);
>  	if (pgd_none(*pgd) || pgd_bad(*pgd))
> 
> 

-- 
David Gibson			| For every complex problem there is a
david AT gibson.dropbear.id.au	| solution which is simple, neat and
				| wrong.
http://www.ozlabs.org/people/dgibson

Re: Kill off hugepage_vma()

[William Lee Irwin III]

On Fri, Apr 16, 2004 at 03:14:39PM -0700, Chen, Kenneth W wrote:
> Minor FYI: on ia64, huge page address is in region 4.

This is an artifact of the implementation, not a hardware limitation.


-- wli