diff options
author | Johannes Weiner <hannes@cmpxchg.org> | 2015-01-08 14:32:18 -0800 |
---|---|---|
committer | Zefan Li <lizefan@huawei.com> | 2015-04-14 17:33:51 +0800 |
commit | 7f1be7c6e55b686ee22b97db779eb7ed01a2f3af (patch) | |
tree | 9a9756e65264a0f6f830481a5cbdcf8e214cc459 /include | |
parent | 0b4f2ae74a52418cd880d9249e65fc935f02e89a (diff) |
mm: protect set_page_dirty() from ongoing truncation
commit 2d6d7f98284648c5ed113fe22a132148950b140f upstream.
Tejun, while reviewing the code, spotted the following race condition
between the dirtying and truncation of a page:
__set_page_dirty_nobuffers() __delete_from_page_cache()
if (TestSetPageDirty(page))
page->mapping = NULL
if (PageDirty())
dec_zone_page_state(page, NR_FILE_DIRTY);
dec_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
if (page->mapping)
account_page_dirtied(page)
__inc_zone_page_state(page, NR_FILE_DIRTY);
__inc_bdi_stat(mapping->backing_dev_info, BDI_RECLAIMABLE);
which results in an imbalance of NR_FILE_DIRTY and BDI_RECLAIMABLE.
Dirtiers usually lock out truncation, either by holding the page lock
directly, or in case of zap_pte_range(), by pinning the mapcount with
the page table lock held. The notable exception to this rule, though,
is do_wp_page(), for which this race exists. However, do_wp_page()
already waits for a locked page to unlock before setting the dirty bit,
in order to prevent a race where clear_page_dirty() misses the page bit
in the presence of dirty ptes. Upgrade that wait to a fully locked
set_page_dirty() to also cover the situation explained above.
Afterwards, the code in set_page_dirty() dealing with a truncation race
is no longer needed. Remove it.
Reported-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Johannes Weiner <hannes@cmpxchg.org>
Acked-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
[lizf: Backported to 3.4:
- adjust context
- use VM_BUG_ON() instead of VM_BUG_ON_PAGE()]
Signed-off-by: Zefan Li <lizefan@huawei.com>
Diffstat (limited to 'include')
-rw-r--r-- | include/linux/writeback.h | 1 |
1 files changed, 0 insertions, 1 deletions
diff --git a/include/linux/writeback.h b/include/linux/writeback.h index a2b84f598e2b..dd8d4918de2e 100644 --- a/include/linux/writeback.h +++ b/include/linux/writeback.h @@ -186,7 +186,6 @@ int write_cache_pages(struct address_space *mapping, struct writeback_control *wbc, writepage_t writepage, void *data); int do_writepages(struct address_space *mapping, struct writeback_control *wbc); -void set_page_dirty_balance(struct page *page, int page_mkwrite); void writeback_set_ratelimit(void); void tag_pages_for_writeback(struct address_space *mapping, pgoff_t start, pgoff_t end); |