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>

1 files changed, 5 insertions, 5 deletions

diff --git a/include/linux/pagemap.h b/include/linux/pagemap.h
index e3dea75..1710d1b 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);