mm: dump page when hitting a VM_BUG_ON using VM_BUG_ON_PAGE

Most of the VM_BUG_ON assertions are performed on a page.  Usually, when
one of these assertions fails we'll get a BUG_ON with a call stack and
the registers.

I've recently noticed based on the requests to add a small piece of code
that dumps the page to various VM_BUG_ON sites that the page dump is
quite useful to people debugging issues in mm.

This patch adds a VM_BUG_ON_PAGE(cond, page) which beyond doing what
VM_BUG_ON() does, also dumps the page before executing the actual
BUG_ON.

[akpm@linux-foundation.org: fix up includes]
Signed-off-by: Sasha Levin <sasha.levin@oracle.com>
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

8 files changed, 39 insertions, 29 deletions

diff --git a/include/linux/gfp.h b/include/linux/gfp.h
index 9b4dd491f7e8..0437439bc047 100644
--- a/include/linux/gfp.h
+++ b/include/linux/gfp.h
@@ -1,6 +1,7 @@
 #ifndef __LINUX_GFP_H
 #define __LINUX_GFP_H
 
+#include <linux/mmdebug.h>
 #include <linux/mmzone.h>
 #include <linux/stddef.h>
 #include <linux/linkage.h>
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index d01cc972a1d9..8c43cc469d78 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -2,6 +2,7 @@
 #define _LINUX_HUGETLB_H
 
 #include <linux/mm_types.h>
+#include <linux/mmdebug.h>
 #include <linux/fs.h>
 #include <linux/hugetlb_inline.h>
 #include <linux/cgroup.h>
@@ -354,7 +355,7 @@ static inline pte_t arch_make_huge_pte(pte_t entry, struct vm_area_struct *vma,
 
 static inline struct hstate *page_hstate(struct page *page)
 {
-	VM_BUG_ON(!PageHuge(page));
+	VM_BUG_ON_PAGE(!PageHuge(page), page);
 	return size_to_hstate(PAGE_SIZE << compound_order(page));
 }
 
diff --git a/include/linux/hugetlb_cgroup.h b/include/linux/hugetlb_cgroup.h
index ce8217f7b5c2..787bba3bf552 100644
--- a/include/linux/hugetlb_cgroup.h
+++ b/include/linux/hugetlb_cgroup.h
@@ -15,6 +15,7 @@
 #ifndef _LINUX_HUGETLB_CGROUP_H
 #define _LINUX_HUGETLB_CGROUP_H
 
+#include <linux/mmdebug.h>
 #include <linux/res_counter.h>
 
 struct hugetlb_cgroup;
@@ -28,7 +29,7 @@ struct hugetlb_cgroup;
 
 static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
 {
-	VM_BUG_ON(!PageHuge(page));
+	VM_BUG_ON_PAGE(!PageHuge(page), page);
 
 	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
 		return NULL;
@@ -38,7 +39,7 @@ static inline struct hugetlb_cgroup *hugetlb_cgroup_from_page(struct page *page)
 static inline
 int set_hugetlb_cgroup(struct page *page, struct hugetlb_cgroup *h_cg)
 {
-	VM_BUG_ON(!PageHuge(page));
+	VM_BUG_ON_PAGE(!PageHuge(page), page);
 
 	if (compound_order(page) < HUGETLB_CGROUP_MIN_ORDER)
 		return -1;
diff --git a/include/linux/mm.h b/include/linux/mm.h
index 03bbcb84d96e..d9992fc128ca 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -5,6 +5,7 @@
 
 #ifdef __KERNEL__
 
+#include <linux/mmdebug.h>
 #include <linux/gfp.h>
 #include <linux/bug.h>
 #include <linux/list.h>
@@ -303,7 +304,7 @@ static inline int get_freepage_migratetype(struct page *page)
  */
 static inline int put_page_testzero(struct page *page)
 {
-	VM_BUG_ON(atomic_read(&page->_count) == 0);
+	VM_BUG_ON_PAGE(atomic_read(&page->_count) == 0, page);
 	return atomic_dec_and_test(&page->_count);
 }
 
@@ -364,7 +365,7 @@ static inline int is_vmalloc_or_module_addr(const void *x)
 static inline void compound_lock(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	VM_BUG_ON(PageSlab(page));
+	VM_BUG_ON_PAGE(PageSlab(page), page);
 	bit_spin_lock(PG_compound_lock, &page->flags);
 #endif
 }
@@ -372,7 +373,7 @@ static inline void compound_lock(struct page *page)
 static inline void compound_unlock(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	VM_BUG_ON(PageSlab(page));
+	VM_BUG_ON_PAGE(PageSlab(page), page);
 	bit_spin_unlock(PG_compound_lock, &page->flags);
 #endif
 }
@@ -447,7 +448,7 @@ static inline bool __compound_tail_refcounted(struct page *page)
  */
 static inline bool compound_tail_refcounted(struct page *page)
 {
-	VM_BUG_ON(!PageHead(page));
+	VM_BUG_ON_PAGE(!PageHead(page), page);
 	return __compound_tail_refcounted(page);
 }
 
@@ -456,9 +457,9 @@ static inline void get_huge_page_tail(struct page *page)
 	/*
 	 * __split_huge_page_refcount() cannot run from under us.
 	 */
-	VM_BUG_ON(!PageTail(page));
-	VM_BUG_ON(page_mapcount(page) < 0);
-	VM_BUG_ON(atomic_read(&page->_count) != 0);
+	VM_BUG_ON_PAGE(!PageTail(page), page);
+	VM_BUG_ON_PAGE(page_mapcount(page) < 0, page);
+	VM_BUG_ON_PAGE(atomic_read(&page->_count) != 0, page);
 	if (compound_tail_refcounted(page->first_page))
 		atomic_inc(&page->_mapcount);
 }
@@ -474,7 +475,7 @@ static inline void get_page(struct page *page)
 	 * Getting a normal page or the head of a compound page
 	 * requires to already have an elevated page->_count.
 	 */
-	VM_BUG_ON(atomic_read(&page->_count) <= 0);
+	VM_BUG_ON_PAGE(atomic_read(&page->_count) <= 0, page);
 	atomic_inc(&page->_count);
 }
 
@@ -511,13 +512,13 @@ static inline int PageBuddy(struct page *page)
 
 static inline void __SetPageBuddy(struct page *page)
 {
-	VM_BUG_ON(atomic_read(&page->_mapcount) != -1);
+	VM_BUG_ON_PAGE(atomic_read(&page->_mapcount) != -1, page);
 	atomic_set(&page->_mapcount, PAGE_BUDDY_MAPCOUNT_VALUE);
 }
 
 static inline void __ClearPageBuddy(struct page *page)
 {
-	VM_BUG_ON(!PageBuddy(page));
+	VM_BUG_ON_PAGE(!PageBuddy(page), page);
 	atomic_set(&page->_mapcount, -1);
 }
 
@@ -1401,7 +1402,7 @@ static inline bool ptlock_init(struct page *page)
 	 * slab code uses page->slab_cache and page->first_page (for tail
 	 * pages), which share storage with page->ptl.
 	 */
-	VM_BUG_ON(*(unsigned long *)&page->ptl);
+	VM_BUG_ON_PAGE(*(unsigned long *)&page->ptl, page);
 	if (!ptlock_alloc(page))
 		return false;
 	spin_lock_init(ptlock_ptr(page));
@@ -1492,7 +1493,7 @@ static inline bool pgtable_pmd_page_ctor(struct page *page)
 static inline void pgtable_pmd_page_dtor(struct page *page)
 {
 #ifdef CONFIG_TRANSPARENT_HUGEPAGE
-	VM_BUG_ON(page->pmd_huge_pte);
+	VM_BUG_ON_PAGE(page->pmd_huge_pte, page);
 #endif
 	ptlock_free(page);
 }
@@ -2029,10 +2030,6 @@ extern void shake_page(struct page *p, int access);
 extern atomic_long_t num_poisoned_pages;
 extern int soft_offline_page(struct page *page, int flags);
 
-extern void dump_page(struct page *page, char *reason);
-extern void dump_page_badflags(struct page *page, char *reason,
-			       unsigned long badflags);
-
 #if defined(CONFIG_TRANSPARENT_HUGEPAGE) || defined(CONFIG_HUGETLBFS)
 extern void clear_huge_page(struct page *page,
 			    unsigned long addr,
diff --git a/include/linux/mmdebug.h b/include/linux/mmdebug.h
index 580bd587d916..5042c036dda9 100644
--- a/include/linux/mmdebug.h
+++ b/include/linux/mmdebug.h
@@ -1,10 +1,19 @@
 #ifndef LINUX_MM_DEBUG_H
 #define LINUX_MM_DEBUG_H 1
 
+struct page;
+
+extern void dump_page(struct page *page, char *reason);
+extern void dump_page_badflags(struct page *page, char *reason,
+			       unsigned long badflags);
+
 #ifdef CONFIG_DEBUG_VM
 #define VM_BUG_ON(cond) BUG_ON(cond)
+#define VM_BUG_ON_PAGE(cond, page) \
+	do { if (unlikely(cond)) { dump_page(page, NULL); BUG(); } } while (0)
 #else
 #define VM_BUG_ON(cond) BUILD_BUG_ON_INVALID(cond)
+#define VM_BUG_ON_PAGE(cond, page) VM_BUG_ON(cond)
 #endif
 
 #ifdef CONFIG_DEBUG_VIRTUAL
diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
index 98ada58f9942..e464b4e987e8 100644
--- a/include/linux/page-flags.h
+++ b/include/linux/page-flags.h
@@ -412,7 +412,7 @@ static inline void ClearPageCompound(struct page *page)
  */
 static inline int PageTransHuge(struct page *page)
 {
-	VM_BUG_ON(PageTail(page));
+	VM_BUG_ON_PAGE(PageTail(page), page);
 	return PageHead(page);
 }
 
@@ -460,25 +460,25 @@ static inline int PageTransTail(struct page *page)
  */
 static inline int PageSlabPfmemalloc(struct page *page)
 {
-	VM_BUG_ON(!PageSlab(page));
+	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	return PageActive(page);
 }
 
 static inline void SetPageSlabPfmemalloc(struct page *page)
 {
-	VM_BUG_ON(!PageSlab(page));
+	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	SetPageActive(page);
 }
 
 static inline void __ClearPageSlabPfmemalloc(struct page *page)
 {
-	VM_BUG_ON(!PageSlab(page));
+	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	__ClearPageActive(page);
 }
 
 static inline void ClearPageSlabPfmemalloc(struct page *page)
 {
-	VM_BUG_ON(!PageSlab(page));
+	VM_BUG_ON_PAGE(!PageSlab(page), page);
 	ClearPageActive(page);
 }
 
diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e3dea75a078b..1710d1b060ba 100644
--- a/include/linux/pagemap.h
+++ b/include/linux/pagemap.h
@@ -162,7 +162,7 @@ static inline int page_cache_get_speculative(struct page *page)
 	 * disabling preempt, and hence no need for the "speculative get" that
 	 * SMP requires.
 	 */
-	VM_BUG_ON(page_count(page) == 0);
+	VM_BUG_ON_PAGE(page_count(page) == 0, page);
 	atomic_inc(&page->_count);
 
 #else
@@ -175,7 +175,7 @@ static inline int page_cache_get_speculative(struct page *page)
 		return 0;
 	}
 #endif
-	VM_BUG_ON(PageTail(page));
+	VM_BUG_ON_PAGE(PageTail(page), page);
 
 	return 1;
 }
@@ -191,14 +191,14 @@ static inline int page_cache_add_speculative(struct page *page, int count)
 # ifdef CONFIG_PREEMPT_COUNT
 	VM_BUG_ON(!in_atomic());
 # endif
-	VM_BUG_ON(page_count(page) == 0);
+	VM_BUG_ON_PAGE(page_count(page) == 0, page);
 	atomic_add(count, &page->_count);
 
 #else
 	if (unlikely(!atomic_add_unless(&page->_count, count, 0)))
 		return 0;
 #endif
-	VM_BUG_ON(PageCompound(page) && page != compound_head(page));
+	VM_BUG_ON_PAGE(PageCompound(page) && page != compound_head(page), page);
 
 	return 1;
 }
@@ -210,7 +210,7 @@ static inline int page_freeze_refs(struct page *page, int count)
 
 static inline void page_unfreeze_refs(struct page *page, int count)
 {
-	VM_BUG_ON(page_count(page) != 0);
+	VM_BUG_ON_PAGE(page_count(page) != 0, page);
 	VM_BUG_ON(count == 0);
 
 	atomic_set(&page->_count, count);
diff --git a/include/linux/percpu.h b/include/linux/percpu.h
index 9e4761caa80c..e3817d2441b6 100644
--- a/include/linux/percpu.h
+++ b/include/linux/percpu.h
@@ -1,6 +1,7 @@
 #ifndef __LINUX_PERCPU_H
 #define __LINUX_PERCPU_H
 
+#include <linux/mmdebug.h>
 #include <linux/preempt.h>
 #include <linux/smp.h>
 #include <linux/cpumask.h>