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authorHugh Dickins <hughd@google.com>2012-10-08 16:33:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2012-10-09 16:22:55 +0900
commitec4d9f626d5908b6052c2973f37992f1db52e967 (patch)
treec1c0dd99680061cb506797f37ed319eb2804329f /mm/truncate.c
parent7ffc0edc49d0df5dac077c1830e2533b27d3a4ed (diff)
mm: fix invalidate_complete_page2() lock ordering
In fuzzing with trinity, lockdep protested "possible irq lock inversion dependency detected" when isolate_lru_page() reenabled interrupts while still holding the supposedly irq-safe tree_lock: invalidate_inode_pages2 invalidate_complete_page2 spin_lock_irq(&mapping->tree_lock) clear_page_mlock isolate_lru_page spin_unlock_irq(&zone->lru_lock) isolate_lru_page() is correct to enable interrupts unconditionally: invalidate_complete_page2() is incorrect to call clear_page_mlock() while holding tree_lock, which is supposed to nest inside lru_lock. Both truncate_complete_page() and invalidate_complete_page() call clear_page_mlock() before taking tree_lock to remove page from radix_tree. I guess invalidate_complete_page2() preferred to test PageDirty (again) under tree_lock before committing to the munlock; but since the page has already been unmapped, its state is already somewhat inconsistent, and no worse if clear_page_mlock() moved up. Reported-by: Sasha Levin <levinsasha928@gmail.com> Deciphered-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Hugh Dickins <hughd@google.com> Acked-by: Mel Gorman <mel@csn.ul.ie> Cc: Rik van Riel <riel@redhat.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michel Lespinasse <walken@google.com> Cc: Ying Han <yinghan@google.com> Cc: <stable@vger.kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/truncate.c')
-rw-r--r--mm/truncate.c3
1 files changed, 2 insertions, 1 deletions
diff --git a/mm/truncate.c b/mm/truncate.c
index 75801acdaac7..f38055cb8af6 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -394,11 +394,12 @@ invalidate_complete_page2(struct address_space *mapping, struct page *page)
if (page_has_private(page) && !try_to_release_page(page, GFP_KERNEL))
return 0;
+ clear_page_mlock(page);
+
spin_lock_irq(&mapping->tree_lock);
if (PageDirty(page))
goto failed;
- clear_page_mlock(page);
BUG_ON(page_has_private(page));
__delete_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);

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