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, 4 insertions, 4 deletions

diff --git a/mm/shmem.c b/mm/shmem.c
index 902a148..8156f95 100644
--- a/mm/shmem.c
+++ b/mm/shmem.c
@@ -285,8 +285,8 @@ static int shmem_add_to_page_cache(struct page *page,
 {
 	int error;
 
-	VM_BUG_ON(!PageLocked(page));
-	VM_BUG_ON(!PageSwapBacked(page));
+	VM_BUG_ON_PAGE(!PageLocked(page), page);
+	VM_BUG_ON_PAGE(!PageSwapBacked(page), page);
 
 	page_cache_get(page);
 	page->mapping = mapping;
@@ -491,7 +491,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 				continue;
 			if (!unfalloc || !PageUptodate(page)) {
 				if (page->mapping == mapping) {
-					VM_BUG_ON(PageWriteback(page));
+					VM_BUG_ON_PAGE(PageWriteback(page), page);
 					truncate_inode_page(mapping, page);
 				}
 			}
@@ -568,7 +568,7 @@ static void shmem_undo_range(struct inode *inode, loff_t lstart, loff_t lend,
 			lock_page(page);
 			if (!unfalloc || !PageUptodate(page)) {
 				if (page->mapping == mapping) {
-					VM_BUG_ON(PageWriteback(page));
+					VM_BUG_ON_PAGE(PageWriteback(page), page);
 					truncate_inode_page(mapping, page);
 				}
 			}