From: Hugh Dickins <hu...@google.com>
-------------------
This is a commit scheduled for the next v2.6.34 longterm release.
http://git.kernel.org/?p=linux/kernel/git/paulg/longterm-queue-2.6.34.git
If you see a problem with using this for longterm, please comment.
-------------------
commit ec4d9f626d5908b6052c2973f37992f1db52e967 upstream.
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 <levinsasha...@gmail.com>
Deciphered-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Hugh Dickins <hu...@google.com>
Acked-by: Mel Gorman <m...@csn.ul.ie>
Cc: Rik van Riel <r...@redhat.com>
Cc: Johannes Weiner <han...@cmpxchg.org>
Cc: Michel Lespinasse <wal...@google.com>
Cc: Ying Han <ying...@google.com>
Signed-off-by: Andrew Morton <a...@linux-foundation.org>
Signed-off-by: Linus Torvalds <torva...@linux-foundation.org>
Signed-off-by: Paul Gortmaker <paul.gortma...@windriver.com>
---
mm/truncate.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
diff --git a/mm/truncate.c b/mm/truncate.c
index f42675a3615d..d0698a15c61f 100644
--- a/mm/truncate.c
+++ b/mm/truncate.c
@@ -381,11 +381,12 @@ 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));
__remove_from_page_cache(page);
spin_unlock_irq(&mapping->tree_lock);
--
1.8.5.2
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