mm: debug check for the fault vs invalidate race

Add a bugcheck for Andrea's pagefault vs invalidate race. This is triggerable for both linear and nonlinear pages with a userspace test harness (using direct IO and truncate, respectively). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm: debug check for the fault vs invalidate race
Add a bugcheck for Andrea's pagefault vs invalidate race. This is triggerable for both linear and nonlinear pages with a userspace test harness (using direct IO and truncate, respectively). Signed-off-by: Nick Piggin <npiggin@suse.de> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Nick Piggin · Linus Torvalds
1 parent f96efd585b
Showing 1 changed file with 1 additions and 0 deletions Side-by-side Diff
mm/filemap.c
@@ -120,6 +120,7 @@
 	page->mapping = NULL;
 	mapping->nrpages--;
 	__dec_zone_page_state(page, NR_FILE_PAGES);
+	BUG_ON(page_mapped(page));
 }
  
 void remove_from_page_cache(struct page *page)
...	...	@@ -120,6 +120,7 @@
120	120	page->mapping = NULL;
121	121	mapping->nrpages--;
122	122	__dec_zone_page_state(page, NR_FILE_PAGES);
	123	+ BUG_ON(page_mapped(page));
123	124	}
124	125
125	126	void remove_from_page_cache(struct page *page)