From: Nick Piggin <npiggin@suse.de>
Date: Mon, 16 Jul 2007 06:38:12 +0000 (-0700)
Subject: mm: debug check for the fault vs invalidate race
X-Git-Tag: v2.6.23-rc1~1027
X-Git-Url: https://err.no/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=45426812d6b601430d560cb6049757b5b0bc71c4;p=linux-2.6

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>
---

diff --git a/mm/filemap.c b/mm/filemap.c
index c6ebd9f912..e006c57bda 100644
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -120,6 +120,7 @@ void __remove_from_page_cache(struct page *page)
 	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)