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/mm/internal.h b/mm/internal.h
index a346ba1..dc95e97 100644
--- a/mm/internal.h
+++ b/mm/internal.h
@@ -27,8 +27,8 @@ static inline void set_page_count(struct page *page, int v)
  */
 static inline void set_page_refcounted(struct page *page)
 {
-	VM_BUG_ON(PageTail(page));
-	VM_BUG_ON(atomic_read(&page->_count));
+	VM_BUG_ON_PAGE(PageTail(page), page);
+	VM_BUG_ON_PAGE(atomic_read(&page->_count), page);
 	set_page_count(page, 1);
 }
 
@@ -46,7 +46,7 @@ static inline void __get_page_tail_foll(struct page *page,
 	 * speculative page access (like in
 	 * page_cache_get_speculative()) on tail pages.
 	 */
-	VM_BUG_ON(atomic_read(&page->first_page->_count) <= 0);
+	VM_BUG_ON_PAGE(atomic_read(&page->first_page->_count) <= 0, page);
 	if (get_page_head)
 		atomic_inc(&page->first_page->_count);
 	get_huge_page_tail(page);
@@ -71,7 +71,7 @@ static inline void get_page_foll(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);
 	}
 }
@@ -173,7 +173,7 @@ static inline void munlock_vma_pages_all(struct vm_area_struct *vma)
 static inline int mlocked_vma_newpage(struct vm_area_struct *vma,
 				    struct page *page)
 {
-	VM_BUG_ON(PageLRU(page));
+	VM_BUG_ON_PAGE(PageLRU(page), page);
 
 	if (likely((vma->vm_flags & (VM_LOCKED | VM_SPECIAL)) != VM_LOCKED))
 		return 0;