diff options
| author | Nick Piggin <npiggin@suse.de> | 2007-07-19 01:47:22 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.linux-foundation.org> | 2007-07-19 10:04:41 -0700 |
| commit | 79352894b28550ee0eee919149f57626ec1b3572 (patch) | |
| tree | 849e6aa148c69b9df3920199255ca14792eeffa2 /mm/memory.c | |
| parent | 83c54070ee1a2d05c89793884bea1a03f2851ed4 (diff) | |
| download | lwn-79352894b28550ee0eee919149f57626ec1b3572.tar.gz lwn-79352894b28550ee0eee919149f57626ec1b3572.zip | |
mm: fix clear_page_dirty_for_io vs fault race
Fix msync data loss and (less importantly) dirty page accounting
inaccuracies due to the race remaining in clear_page_dirty_for_io().
The deleted comment explains what the race was, and the added comments
explain how it is fixed.
Signed-off-by: Nick Piggin <npiggin@suse.de>
Acked-by: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Miklos Szeredi <miklos@szeredi.hu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/memory.c')
| -rw-r--r-- | mm/memory.c | 9 |
1 files changed, 9 insertions, 0 deletions
diff --git a/mm/memory.c b/mm/memory.c index 61d51da7e17c..50dd3d1f4d18 100644 --- a/mm/memory.c +++ b/mm/memory.c @@ -1765,6 +1765,15 @@ gotten: unlock: pte_unmap_unlock(page_table, ptl); if (dirty_page) { + /* + * Yes, Virginia, this is actually required to prevent a race + * with clear_page_dirty_for_io() from clearing the page dirty + * bit after it clear all dirty ptes, but before a racing + * do_wp_page installs a dirty pte. + * + * do_no_page is protected similarly. + */ + wait_on_page_locked(dirty_page); set_page_dirty_balance(dirty_page); put_page(dirty_page); } |