| From 65cf71358a4d8a67b71706d7a539dd3d89400bea Mon Sep 17 00:00:00 2001 |
| From: Hugh Dickins <hughd@google.com> |
| Date: Mon, 8 Oct 2012 16:33:14 -0700 |
| Subject: [PATCH] mm: fix invalidate_complete_page2() lock ordering |
| |
| 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 <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> |
| Signed-off-by: Andrew Morton <akpm@linux-foundation.org> |
| Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> |
| Signed-off-by: Paul Gortmaker <paul.gortmaker@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 |
| |
