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, 8 insertions, 8 deletions

diff --git a/mm/filemap.c b/mm/filemap.c
index b7749a92021c..7a7f3e0db738 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -409,9 +409,9 @@ int replace_page_cache_page(struct page *old, struct page *new, gfp_t gfp_mask)
 {
         int error;
 
-        VM_BUG_ON(!PageLocked(old));
-        VM_BUG_ON(!PageLocked(new));
-        VM_BUG_ON(new->mapping);
+        VM_BUG_ON_PAGE(!PageLocked(old), old);
+        VM_BUG_ON_PAGE(!PageLocked(new), new);
+        VM_BUG_ON_PAGE(new->mapping, new);
 
         error = radix_tree_preload(gfp_mask & ~__GFP_HIGHMEM);
         if (!error) {
@@ -461,8 +461,8 @@ int add_to_page_cache_locked(struct page *page, struct address_space *mapping,
 {
         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);
 
         error = mem_cgroup_cache_charge(page, current->mm,
                                         gfp_mask & GFP_RECLAIM_MASK);
@@ -607,7 +607,7 @@ EXPORT_SYMBOL_GPL(add_page_wait_queue);
  */
 void unlock_page(struct page *page)
 {
-        VM_BUG_ON(!PageLocked(page));
+        VM_BUG_ON_PAGE(!PageLocked(page), page);
         clear_bit_unlock(PG_locked, &page->flags);
         smp_mb__after_clear_bit();
         wake_up_page(page, PG_locked);
@@ -760,7 +760,7 @@ repeat:
                         page_cache_release(page);
                         goto repeat;
                 }
-                VM_BUG_ON(page->index != offset);
+                VM_BUG_ON_PAGE(page->index != offset, page);
         }
         return page;
 }
@@ -1656,7 +1656,7 @@ retry_find:
                 put_page(page);
                 goto retry_find;
         }
-        VM_BUG_ON(page->index != offset);
+        VM_BUG_ON_PAGE(page->index != offset, page);
 
         /*
          * We have a locked page in the page cache, now we need to check