[PATCH 1/3] Introduce dump_vma

[PATCH 1/3] Introduce dump_vma

[Sasha Levin]

Introduce a helper to dump information about a VMA, this also
makes dump_page_flags more generic and re-uses that so the
output looks very similar to dump_page:

[   61.903437] vma ffff88070f88be00 start 00007fff25970000 end 00007fff25992000
[   61.903437] next ffff88070facd600 prev ffff88070face400 mm ffff88070fade000
[   61.903437] prot 8000000000000025 anon_vma ffff88070fa1e200 vm_ops           (null)
[   61.903437] pgoff 7ffffffdd file           (null) private_data           (null)
[   61.909129] flags: 0x100173(read|write|mayread|maywrite|mayexec|growsdown|account)

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 include/linux/mmdebug.h |    2 ++
 mm/page_alloc.c         |   77 +++++++++++++++++++++++++++++++++++++++++------
 2 files changed, 70 insertions(+), 9 deletions(-)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 2f348d0..dfb9333 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -4,10 +4,12 @@
 #include <linux/stringify.h>
 
 struct page;
+struct vm_area_struct;
 
 extern void dump_page(struct page *page, const char *reason);
 extern void dump_page_badflags(struct page *page, const char *reason,
 			       unsigned long badflags);
+void dump_vma(const struct vm_area_struct *vma);
 
 #ifdef CONFIG_DEBUG_VM
 #define VM_BUG_ON(cond) BUG_ON(cond)
diff --git a/mm/page_alloc.c b/mm/page_alloc.c
index f86023b..add97b8 100644
--- a/mm/page_alloc.c
+++ b/mm/page_alloc.c
@@ -6628,27 +6628,26 @@ static const struct trace_print_flags pageflag_names[] = {
 #endif
 };
 
-static void dump_page_flags(unsigned long flags)
+static void dump_flags(unsigned long flags,
+			const struct trace_print_flags *names, int count)
 {
 	const char *delim = "";
 	unsigned long mask;
 	int i;
 
-	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
-
-	printk(KERN_ALERT "page flags: %#lx(", flags);
+	printk(KERN_ALERT "flags: %#lx(", flags);
 
 	/* remove zone id */
 	flags &= (1UL << NR_PAGEFLAGS) - 1;
 
-	for (i = 0; i < ARRAY_SIZE(pageflag_names) && flags; i++) {
+	for (i = 0; i < count && flags; i++) {
 
-		mask = pageflag_names[i].mask;
+		mask = names[i].mask;
 		if ((flags & mask) != mask)
 			continue;
 
 		flags &= ~mask;
-		printk("%s%s", delim, pageflag_names[i].name);
+		printk("%s%s", delim, names[i].name);
 		delim = "|";
 	}
 
@@ -6666,12 +6665,14 @@ void dump_page_badflags(struct page *page, const char *reason,
 	       "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
 		page, atomic_read(&page->_count), page_mapcount(page),
 		page->mapping, page->index);
-	dump_page_flags(page->flags);
+	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
+	dump_flags(page->flags, pageflag_names, ARRAY_SIZE(pageflag_names));
 	if (reason)
 		pr_alert("page dumped because: %s\n", reason);
 	if (page->flags & badflags) {
 		pr_alert("bad because of flags:\n");
-		dump_page_flags(page->flags & badflags);
+		dump_flags(page->flags & badflags,
+				pageflag_names, ARRAY_SIZE(pageflag_names));
 	}
 	mem_cgroup_print_bad_page(page);
 }
@@ -6681,3 +6682,61 @@ void dump_page(struct page *page, const char *reason)
 	dump_page_badflags(page, reason, 0);
 }
 EXPORT_SYMBOL(dump_page);
+
+static const struct trace_print_flags vmaflags_names[] = {
+	{VM_READ,			"read"		},
+	{VM_WRITE,			"write"		},
+	{VM_EXEC,			"exec"		},
+	{VM_SHARED,			"shared"	},
+	{VM_MAYREAD,			"mayread"	},
+	{VM_MAYWRITE,			"maywrite"	},
+	{VM_MAYEXEC,			"mayexec"	},
+	{VM_MAYSHARE,			"mayshare"	},
+	{VM_GROWSDOWN,			"growsdown"	},
+	{VM_PFNMAP,			"pfnmap"	},
+	{VM_DENYWRITE,			"denywrite"	},
+	{VM_LOCKED,			"locked"	},
+	{VM_IO,				"io"		},
+	{VM_SEQ_READ,			"seqread"	},
+	{VM_RAND_READ,			"randread"	},
+	{VM_DONTCOPY,			"dontcopy"	},
+	{VM_DONTEXPAND,			"dontexpand"	},
+	{VM_ACCOUNT,			"account"	},
+	{VM_NORESERVE,			"noreserve"	},
+	{VM_HUGETLB,			"hugetlb"	},
+	{VM_NONLINEAR,			"nonlinear"	},
+#if defined(CONFIG_X86)
+	{VM_PAT,			"pat"		},
+#elif defined(CONFIG_PPC)
+	{VM_SAO,			"sao"		},
+#elif defined(CONFIG_PARISC) || defined(CONFIG_METAG) || defined(CONFIG_IA64)
+	{VM_GROWSUP,			"growsup"	},
+#elif !defined(CONFIG_MMU)
+	{VM_MAPPED_COPY,		"mappedcopy"	},
+#else
+	{VM_ARCH_1,			"arch_1"	},
+#endif
+	{VM_DONTDUMP,			"dontdump"	},
+#ifdef CONFIG_MEM_SOFT_DIRTY
+	{VM_SOFTDIRTY,			"softdirty"	},
+#endif
+	{VM_MIXEDMAP,			"mixedmap"	},
+	{VM_HUGEPAGE,			"hugepage"	},
+	{VM_NOHUGEPAGE,			"nohugepage"	},
+	{VM_MERGEABLE,			"mergeable"	},
+};
+
+void dump_vma(const struct vm_area_struct *vma)
+{
+	printk(KERN_ALERT
+		"vma %p start %p end %p\n"
+		"next %p prev %p mm %p\n"
+		"prot %lx anon_vma %p vm_ops %p\n"
+		"pgoff %lx file %p private_data %p\n",
+		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
+		vma->vm_prev, vma->vm_mm, vma->vm_page_prot.pgprot,
+		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
+		vma->vm_file, vma->vm_private_data);
+	dump_flags(vma->vm_flags, vmaflags_names, ARRAY_SIZE(vmaflags_names));
+}
+EXPORT_SYMBOL(dump_vma);
-- 
1.7.10.4

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[PATCH 2/3] Introduce VM_BUG_ON_VMA

[Sasha Levin]

Very similar to VM_BUG_ON_PAGE but dumps VMA information instead.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 include/linux/mmdebug.h |    8 ++++++++
 1 file changed, 8 insertions(+)

diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index dfb9333..569e4c8 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -20,12 +20,20 @@ void dump_vma(const struct vm_area_struct *vma);
 			BUG();						\
 		}							\
 	} while (0)
+#define VM_BUG_ON_VMA(cond, vma)					\
+	do {								\
+		if (unlikely(cond)) {					\
+			dump_vma(vma);					\
+			BUG();						\
+		}							\
+	} while (0)
 #define VM_WARN_ON(cond) WARN_ON(cond)
 #define VM_WARN_ON_ONCE(cond) WARN_ON_ONCE(cond)
 #define VM_WARN_ONCE(cond, format...) WARN_ONCE(cond, format)
 #else
 #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
+#define VM_BUG_ON_VMA(cond, vma) VM_BUG_ON(cond)
 #define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
 #define VM_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
-- 
1.7.10.4

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[PATCH 3/3] Convert a few VM_BUG_ON callers to VM_BUG_ON_VMA

[Sasha Levin]

Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract
more information when they trigger.

Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
---
 include/linux/huge_mm.h |    2 +-
 include/linux/rmap.h    |    2 +-
 mm/huge_memory.c        |    6 +++---
 mm/hugetlb.c            |   14 +++++++-------
 mm/interval_tree.c      |    2 +-
 mm/mlock.c              |    4 ++--
 mm/mmap.c               |    6 +++---
 mm/mremap.c             |    2 +-
 mm/rmap.c               |    8 ++++----
 9 files changed, 23 insertions(+), 23 deletions(-)

diff --git a/include/linux/huge_mm.h b/include/linux/huge_mm.h
index 63579cb..ad9051b 100644
--- a/include/linux/huge_mm.h
+++ b/include/linux/huge_mm.h
@@ -132,7 +132,7 @@ extern int __pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
 static inline int pmd_trans_huge_lock(pmd_t *pmd, struct vm_area_struct *vma,
 		spinlock_t **ptl)
 {
-	VM_BUG_ON(!rwsem_is_locked(&vma->vm_mm->mmap_sem));
+	VM_BUG_ON_VMA(!rwsem_is_locked(&vma->vm_mm->mmap_sem), vma);
 	if (pmd_trans_huge(*pmd))
 		return __pmd_trans_huge_lock(pmd, vma, ptl);
 	else
diff --git a/include/linux/rmap.h b/include/linux/rmap.h
index be57450..c0c2bce 100644
--- a/include/linux/rmap.h
+++ b/include/linux/rmap.h
@@ -150,7 +150,7 @@ int anon_vma_fork(struct vm_area_struct *, struct vm_area_struct *);
 static inline void anon_vma_merge(struct vm_area_struct *vma,
 				  struct vm_area_struct *next)
 {
-	VM_BUG_ON(vma->anon_vma != next->anon_vma);
+	VM_BUG_ON_VMA(vma->anon_vma != next->anon_vma, vma);
 	unlink_anon_vmas(next);
 }
 
diff --git a/mm/huge_memory.c b/mm/huge_memory.c
index 7cfc325..d81f8ba 100644
--- a/mm/huge_memory.c
+++ b/mm/huge_memory.c
@@ -1096,7 +1096,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
 	unsigned long mmun_end;		/* For mmu_notifiers */
 
 	ptl = pmd_lockptr(mm, pmd);
-	VM_BUG_ON(!vma->anon_vma);
+	VM_BUG_ON_VMA(!vma->anon_vma, vma);
 	haddr = address & HPAGE_PMD_MASK;
 	if (is_huge_zero_pmd(orig_pmd))
 		goto alloc;
@@ -2080,7 +2080,7 @@ int khugepaged_enter_vma_merge(struct vm_area_struct *vma)
 	if (vma->vm_ops)
 		/* khugepaged not yet working on file or special mappings */
 		return 0;
-	VM_BUG_ON(vma->vm_flags & VM_NO_THP);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
 	hstart = (vma->vm_start + ~HPAGE_PMD_MASK) & HPAGE_PMD_MASK;
 	hend = vma->vm_end & HPAGE_PMD_MASK;
 	if (hstart < hend)
@@ -2403,7 +2403,7 @@ static bool hugepage_vma_check(struct vm_area_struct *vma)
 		return false;
 	if (is_vma_temporary_stack(vma))
 		return false;
-	VM_BUG_ON(vma->vm_flags & VM_NO_THP);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_NO_THP, vma);
 	return true;
 }
 
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index eeceeeb..9fd7227 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -434,7 +434,7 @@ static inline struct resv_map *inode_resv_map(struct inode *inode)
 
 static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
 {
-	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 	if (vma->vm_flags & VM_MAYSHARE) {
 		struct address_space *mapping = vma->vm_file->f_mapping;
 		struct inode *inode = mapping->host;
@@ -449,8 +449,8 @@ static struct resv_map *vma_resv_map(struct vm_area_struct *vma)
 
 static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
 {
-	VM_BUG_ON(!is_vm_hugetlb_page(vma));
-	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
 
 	set_vma_private_data(vma, (get_vma_private_data(vma) &
 				HPAGE_RESV_MASK) | (unsigned long)map);
@@ -458,15 +458,15 @@ static void set_vma_resv_map(struct vm_area_struct *vma, struct resv_map *map)
 
 static void set_vma_resv_flags(struct vm_area_struct *vma, unsigned long flags)
 {
-	VM_BUG_ON(!is_vm_hugetlb_page(vma));
-	VM_BUG_ON(vma->vm_flags & VM_MAYSHARE);
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
+	VM_BUG_ON_VMA(vma->vm_flags & VM_MAYSHARE, vma);
 
 	set_vma_private_data(vma, get_vma_private_data(vma) | flags);
 }
 
 static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
 {
-	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 
 	return (get_vma_private_data(vma) & flag) != 0;
 }
@@ -474,7 +474,7 @@ static int is_vma_resv_set(struct vm_area_struct *vma, unsigned long flag)
 /* Reset counters to 0 and clear all HPAGE_RESV_* flags */
 void reset_vma_resv_huge_pages(struct vm_area_struct *vma)
 {
-	VM_BUG_ON(!is_vm_hugetlb_page(vma));
+	VM_BUG_ON_VMA(!is_vm_hugetlb_page(vma), vma);
 	if (!(vma->vm_flags & VM_MAYSHARE))
 		vma->vm_private_data = (void *)0;
 }
diff --git a/mm/interval_tree.c b/mm/interval_tree.c
index 4a5822a..8da581f 100644
--- a/mm/interval_tree.c
+++ b/mm/interval_tree.c
@@ -34,7 +34,7 @@ void vma_interval_tree_insert_after(struct vm_area_struct *node,
 	struct vm_area_struct *parent;
 	unsigned long last = vma_last_pgoff(node);
 
-	VM_BUG_ON(vma_start_pgoff(node) != vma_start_pgoff(prev));
+	VM_BUG_ON_VMA(vma_start_pgoff(node) != vma_start_pgoff(prev), node);
 
 	if (!prev->shared.linear.rb.rb_right) {
 		parent = prev;
diff --git a/mm/mlock.c b/mm/mlock.c
index ce84cb0..d5d09d0 100644
--- a/mm/mlock.c
+++ b/mm/mlock.c
@@ -233,8 +233,8 @@ long __mlock_vma_pages_range(struct vm_area_struct *vma,
 
 	VM_BUG_ON(start & ~PAGE_MASK);
 	VM_BUG_ON(end   & ~PAGE_MASK);
-	VM_BUG_ON(start < vma->vm_start);
-	VM_BUG_ON(end   > vma->vm_end);
+	VM_BUG_ON_VMA(start < vma->vm_start, vma);
+	VM_BUG_ON_VMA(end   > vma->vm_end, vma);
 	VM_BUG_ON(!rwsem_is_locked(&mm->mmap_sem));
 
 	gup_flags = FOLL_TOUCH | FOLL_MLOCK;
diff --git a/mm/mmap.c b/mm/mmap.c
index 45dc9ac..9351482 100644
--- a/mm/mmap.c
+++ b/mm/mmap.c
@@ -786,8 +786,8 @@ again:			remove_next = 1 + (end > next->vm_end);
 	if (!anon_vma && adjust_next)
 		anon_vma = next->anon_vma;
 	if (anon_vma) {
-		VM_BUG_ON(adjust_next && next->anon_vma &&
-			  anon_vma != next->anon_vma);
+		VM_BUG_ON_VMA(adjust_next && next->anon_vma &&
+			  anon_vma != next->anon_vma, next);
 		anon_vma_lock_write(anon_vma);
 		anon_vma_interval_tree_pre_update_vma(vma);
 		if (adjust_next)
@@ -2917,7 +2917,7 @@ struct vm_area_struct *copy_vma(struct vm_area_struct **vmap,
 			 * safe. It is only safe to keep the vm_pgoff
 			 * linear if there are no pages mapped yet.
 			 */
-			VM_BUG_ON(faulted_in_anon_vma);
+			VM_BUG_ON_VMA(faulted_in_anon_vma, new_vma);
 			*vmap = vma = new_vma;
 		}
 		*need_rmap_locks = (new_vma->vm_pgoff <= vma->vm_pgoff);
diff --git a/mm/mremap.c b/mm/mremap.c
index 05f1180..ba7d241 100644
--- a/mm/mremap.c
+++ b/mm/mremap.c
@@ -195,7 +195,7 @@ unsigned long move_page_tables(struct vm_area_struct *vma,
 		if (pmd_trans_huge(*old_pmd)) {
 			int err = 0;
 			if (extent == HPAGE_PMD_SIZE) {
-				VM_BUG_ON(vma->vm_file || !vma->anon_vma);
+				VM_BUG_ON_VMA(vma->vm_file || !vma->anon_vma, vma);
 				/* See comment in move_ptes() */
 				if (need_rmap_locks)
 					anon_vma_lock_write(vma->anon_vma);
diff --git a/mm/rmap.c b/mm/rmap.c
index 3e8491c..5fbd0fe 100644
--- a/mm/rmap.c
+++ b/mm/rmap.c
@@ -527,7 +527,7 @@ vma_address(struct page *page, struct vm_area_struct *vma)
 	unsigned long address = __vma_address(page, vma);
 
 	/* page should be within @vma mapping range */
-	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
 
 	return address;
 }
@@ -897,7 +897,7 @@ void page_move_anon_rmap(struct page *page,
 	struct anon_vma *anon_vma = vma->anon_vma;
 
 	VM_BUG_ON_PAGE(!PageLocked(page), page);
-	VM_BUG_ON(!anon_vma);
+	VM_BUG_ON_VMA(!anon_vma, vma);
 	VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);
 
 	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
@@ -1024,7 +1024,7 @@ void do_page_add_anon_rmap(struct page *page,
 void page_add_new_anon_rmap(struct page *page,
 	struct vm_area_struct *vma, unsigned long address)
 {
-	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
+	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
 	SetPageSwapBacked(page);
 	atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
 	if (PageTransHuge(page))
@@ -1666,7 +1666,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
 	 * structure at mapping cannot be freed and reused yet,
 	 * so we can safely take mapping->i_mmap_mutex.
 	 */
-	VM_BUG_ON(!PageLocked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
 
 	if (!mapping)
 		return ret;
-- 
1.7.10.4

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Re: [PATCH 1/3] Introduce dump_vma

[Naoya Horiguchi]

On Fri, Aug 29, 2014 at 10:54:17AM -0400, Sasha Levin wrote:
> Introduce a helper to dump information about a VMA, this also
> makes dump_page_flags more generic and re-uses that so the
> output looks very similar to dump_page:
> 
> [   61.903437] vma ffff88070f88be00 start 00007fff25970000 end 00007fff25992000
> [   61.903437] next ffff88070facd600 prev ffff88070face400 mm ffff88070fade000
> [   61.903437] prot 8000000000000025 anon_vma ffff88070fa1e200 vm_ops           (null)
> [   61.903437] pgoff 7ffffffdd file           (null) private_data           (null)
> [   61.909129] flags: 0x100173(read|write|mayread|maywrite|mayexec|growsdown|account)
> 
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

# checkpatch.pl shows warnings on using printk(KERN_ALERT), but there
# are many other lines using printk in this file, so it should be done
# as a whole in a separate patch.

Thanks,
Naoya Horiguchi

> ---
>  include/linux/mmdebug.h |    2 ++
>  mm/page_alloc.c         |   77 +++++++++++++++++++++++++++++++++++++++++------
>  2 files changed, 70 insertions(+), 9 deletions(-)
> 
> diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
> index 2f348d0..dfb9333 100644
> --- a/include/linux/mmdebug.h
> +++ b/include/linux/mmdebug.h
> @@ -4,10 +4,12 @@
>  #include <linux/stringify.h>
>  
>  struct page;
> +struct vm_area_struct;
>  
>  extern void dump_page(struct page *page, const char *reason);
>  extern void dump_page_badflags(struct page *page, const char *reason,
>  			       unsigned long badflags);
> +void dump_vma(const struct vm_area_struct *vma);
>  
>  #ifdef CONFIG_DEBUG_VM
>  #define VM_BUG_ON(cond) BUG_ON(cond)
> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
> index f86023b..add97b8 100644
> --- a/mm/page_alloc.c
> +++ b/mm/page_alloc.c
> @@ -6628,27 +6628,26 @@ static const struct trace_print_flags pageflag_names[] = {
>  #endif
>  };
>  
> -static void dump_page_flags(unsigned long flags)
> +static void dump_flags(unsigned long flags,
> +			const struct trace_print_flags *names, int count)
>  {
>  	const char *delim = "";
>  	unsigned long mask;
>  	int i;
>  
> -	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
> -
> -	printk(KERN_ALERT "page flags: %#lx(", flags);
> +	printk(KERN_ALERT "flags: %#lx(", flags);
>  
>  	/* remove zone id */
>  	flags &= (1UL << NR_PAGEFLAGS) - 1;
>  
> -	for (i = 0; i < ARRAY_SIZE(pageflag_names) && flags; i++) {
> +	for (i = 0; i < count && flags; i++) {
>  
> -		mask = pageflag_names[i].mask;
> +		mask = names[i].mask;
>  		if ((flags & mask) != mask)
>  			continue;
>  
>  		flags &= ~mask;
> -		printk("%s%s", delim, pageflag_names[i].name);
> +		printk("%s%s", delim, names[i].name);
>  		delim = "|";
>  	}
>  
> @@ -6666,12 +6665,14 @@ void dump_page_badflags(struct page *page, const char *reason,
>  	       "page:%p count:%d mapcount:%d mapping:%p index:%#lx\n",
>  		page, atomic_read(&page->_count), page_mapcount(page),
>  		page->mapping, page->index);
> -	dump_page_flags(page->flags);
> +	BUILD_BUG_ON(ARRAY_SIZE(pageflag_names) != __NR_PAGEFLAGS);
> +	dump_flags(page->flags, pageflag_names, ARRAY_SIZE(pageflag_names));
>  	if (reason)
>  		pr_alert("page dumped because: %s\n", reason);
>  	if (page->flags & badflags) {
>  		pr_alert("bad because of flags:\n");
> -		dump_page_flags(page->flags & badflags);
> +		dump_flags(page->flags & badflags,
> +				pageflag_names, ARRAY_SIZE(pageflag_names));
>  	}
>  	mem_cgroup_print_bad_page(page);
>  }
> @@ -6681,3 +6682,61 @@ void dump_page(struct page *page, const char *reason)
>  	dump_page_badflags(page, reason, 0);
>  }
>  EXPORT_SYMBOL(dump_page);
> +
> +static const struct trace_print_flags vmaflags_names[] = {
> +	{VM_READ,			"read"		},
> +	{VM_WRITE,			"write"		},
> +	{VM_EXEC,			"exec"		},
> +	{VM_SHARED,			"shared"	},
> +	{VM_MAYREAD,			"mayread"	},
> +	{VM_MAYWRITE,			"maywrite"	},
> +	{VM_MAYEXEC,			"mayexec"	},
> +	{VM_MAYSHARE,			"mayshare"	},
> +	{VM_GROWSDOWN,			"growsdown"	},
> +	{VM_PFNMAP,			"pfnmap"	},
> +	{VM_DENYWRITE,			"denywrite"	},
> +	{VM_LOCKED,			"locked"	},
> +	{VM_IO,				"io"		},
> +	{VM_SEQ_READ,			"seqread"	},
> +	{VM_RAND_READ,			"randread"	},
> +	{VM_DONTCOPY,			"dontcopy"	},
> +	{VM_DONTEXPAND,			"dontexpand"	},
> +	{VM_ACCOUNT,			"account"	},
> +	{VM_NORESERVE,			"noreserve"	},
> +	{VM_HUGETLB,			"hugetlb"	},
> +	{VM_NONLINEAR,			"nonlinear"	},
> +#if defined(CONFIG_X86)
> +	{VM_PAT,			"pat"		},
> +#elif defined(CONFIG_PPC)
> +	{VM_SAO,			"sao"		},
> +#elif defined(CONFIG_PARISC) || defined(CONFIG_METAG) || defined(CONFIG_IA64)
> +	{VM_GROWSUP,			"growsup"	},
> +#elif !defined(CONFIG_MMU)
> +	{VM_MAPPED_COPY,		"mappedcopy"	},
> +#else
> +	{VM_ARCH_1,			"arch_1"	},
> +#endif
> +	{VM_DONTDUMP,			"dontdump"	},
> +#ifdef CONFIG_MEM_SOFT_DIRTY
> +	{VM_SOFTDIRTY,			"softdirty"	},
> +#endif
> +	{VM_MIXEDMAP,			"mixedmap"	},
> +	{VM_HUGEPAGE,			"hugepage"	},
> +	{VM_NOHUGEPAGE,			"nohugepage"	},
> +	{VM_MERGEABLE,			"mergeable"	},
> +};
> +
> +void dump_vma(const struct vm_area_struct *vma)
> +{
> +	printk(KERN_ALERT
> +		"vma %p start %p end %p\n"
> +		"next %p prev %p mm %p\n"
> +		"prot %lx anon_vma %p vm_ops %p\n"
> +		"pgoff %lx file %p private_data %p\n",
> +		vma, (void *)vma->vm_start, (void *)vma->vm_end, vma->vm_next,
> +		vma->vm_prev, vma->vm_mm, vma->vm_page_prot.pgprot,
> +		vma->anon_vma, vma->vm_ops, vma->vm_pgoff,
> +		vma->vm_file, vma->vm_private_data);
> +	dump_flags(vma->vm_flags, vmaflags_names, ARRAY_SIZE(vmaflags_names));
> +}
> +EXPORT_SYMBOL(dump_vma);
> -- 
> 1.7.10.4
> 
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Re: [PATCH 2/3] Introduce VM_BUG_ON_VMA

[Naoya Horiguchi]

On Fri, Aug 29, 2014 at 10:54:18AM -0400, Sasha Levin wrote:
> Very similar to VM_BUG_ON_PAGE but dumps VMA information instead.
> 
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

> ---
>  include/linux/mmdebug.h |    8 ++++++++
>  1 file changed, 8 insertions(+)
> 
> diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
> index dfb9333..569e4c8 100644
> --- a/include/linux/mmdebug.h
> +++ b/include/linux/mmdebug.h
> @@ -20,12 +20,20 @@ void dump_vma(const struct vm_area_struct *vma);
>  			BUG();						\
>  		}							\
>  	} while (0)
> +#define VM_BUG_ON_VMA(cond, vma)					\
> +	do {								\
> +		if (unlikely(cond)) {					\
> +			dump_vma(vma);					\
> +			BUG();						\
> +		}							\
> +	} while (0)
>  #define VM_WARN_ON(cond) WARN_ON(cond)
>  #define VM_WARN_ON_ONCE(cond) WARN_ON_ONCE(cond)
>  #define VM_WARN_ONCE(cond, format...) WARN_ONCE(cond, format)
>  #else
>  #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
>  #define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
> +#define VM_BUG_ON_VMA(cond, vma) VM_BUG_ON(cond)
>  #define VM_WARN_ON(cond) BUILD_BUG_ON_INVALID(cond)
>  #define VM_WARN_ON_ONCE(cond) BUILD_BUG_ON_INVALID(cond)
>  #define VM_WARN_ONCE(cond, format...) BUILD_BUG_ON_INVALID(cond)
> -- 
> 1.7.10.4
> 
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Re: [PATCH 3/3] Convert a few VM_BUG_ON callers to VM_BUG_ON_VMA

[Naoya Horiguchi]

On Fri, Aug 29, 2014 at 10:54:19AM -0400, Sasha Levin wrote:
> Trivially convert a few VM_BUG_ON calls to VM_BUG_ON_VMA to extract
> more information when they trigger.
> 
> Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
> ---
...
> diff --git a/mm/rmap.c b/mm/rmap.c
> index 3e8491c..5fbd0fe 100644
> --- a/mm/rmap.c
> +++ b/mm/rmap.c
...
> @@ -897,7 +897,7 @@ void page_move_anon_rmap(struct page *page,
>  	struct anon_vma *anon_vma = vma->anon_vma;
>  
>  	VM_BUG_ON_PAGE(!PageLocked(page), page);
> -	VM_BUG_ON(!anon_vma);
> +	VM_BUG_ON_VMA(!anon_vma, vma);

>  	VM_BUG_ON_PAGE(page->index != linear_page_index(vma, address), page);

This line contains both of vma and page.
But I'm not sure that introducing another macro like VM_BUG_ON_PAGE_AND_VMA()
is worth doing. So it's ok for me to keep it untouched.

>  
>  	anon_vma = (void *) anon_vma + PAGE_MAPPING_ANON;
> @@ -1024,7 +1024,7 @@ void do_page_add_anon_rmap(struct page *page,
>  void page_add_new_anon_rmap(struct page *page,
>  	struct vm_area_struct *vma, unsigned long address)
>  {
> -	VM_BUG_ON(address < vma->vm_start || address >= vma->vm_end);
> +	VM_BUG_ON_VMA(address < vma->vm_start || address >= vma->vm_end, vma);
>  	SetPageSwapBacked(page);
>  	atomic_set(&page->_mapcount, 0); /* increment count (starts at -1) */
>  	if (PageTransHuge(page))
> @@ -1666,7 +1666,7 @@ static int rmap_walk_file(struct page *page, struct rmap_walk_control *rwc)
>  	 * structure at mapping cannot be freed and reused yet,
>  	 * so we can safely take mapping->i_mmap_mutex.
>  	 */
> -	VM_BUG_ON(!PageLocked(page));
> +	VM_BUG_ON_PAGE(!PageLocked(page), page);

This is not the replacement with VM_BUG_ON_VMA(), but it's fine :)

Reviewed-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>

Thanks,
Naoya Horiguchi

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Re: [PATCH 3/3] Convert a few VM_BUG_ON callers to VM_BUG_ON_VMA

[Sasha Levin]

On 08/29/2014 03:17 PM, Naoya Horiguchi wrote:
>> -	VM_BUG_ON(!PageLocked(page));
>> > +	VM_BUG_ON_PAGE(!PageLocked(page), page);
> This is not the replacement with VM_BUG_ON_VMA(), but it's fine :)

Woops, I was on a spree and got this one as well.

Thanks for the review Naoya!


Thanks,
Sasha

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Re: [PATCH 1/3] Introduce dump_vma

[Andrew Morton]

On Fri, 29 Aug 2014 10:54:17 -0400 Sasha Levin <sasha.levin@oracle.com> wrote:

> Introduce a helper to dump information about a VMA, this also
> makes dump_page_flags more generic and re-uses that so the
> output looks very similar to dump_page:
> 

That's another kilobyte which we don't actually use unless
CONFIG_DEBUG_VM, so how about we do

--- a/mm/page_alloc.c~introduce-dump_vma-fix
+++ a/mm/page_alloc.c
@@ -6683,6 +6683,8 @@ void dump_page(struct page *page, const
 }
 EXPORT_SYMBOL(dump_page);
 
+#ifdef CONFIG_DEBUG_VM
+
 static const struct trace_print_flags vmaflags_names[] = {
 	{VM_READ,			"read"		},
 	{VM_WRITE,			"write"		},
@@ -6740,3 +6742,5 @@ void dump_vma(const struct vm_area_struc
 	dump_flags(vma->vm_flags, vmaflags_names, ARRAY_SIZE(vmaflags_names));
 }
 EXPORT_SYMBOL(dump_vma);
+
+#endif		/* CONFIG_DEBUG_VM */

until someone needs it from non-debug code?

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