diff options
| author | Anssi Hannula <anssi.hannula@iki.fi> | 2014-08-01 11:55:47 -0400 |
|---|---|---|
| committer | Jiri Slaby <jslaby@suse.cz> | 2014-08-19 14:23:37 +0200 |
| commit | 49cbb95e7c78ca45aad2d985fc7f186ec6020dbc (patch) | |
| tree | 145db3cfdbdb3d057d35de6c8c73d4f9f3fcffc9 /kernel | |
| parent | 9ee4fa038c195fc4ccd45aedaafbc8fd489ec33b (diff) | |
dm cache: fix race affecting dirty block count
commit 44fa816bb778edbab6b6ddaaf24908dd6295937e upstream.
nr_dirty is updated without locking, causing it to drift so that it is
non-zero (either a small positive integer, or a very large one when an
underflow occurs) even when there are no actual dirty blocks. This was
due to a race between the workqueue and map function accessing nr_dirty
in parallel without proper protection.
People were seeing under runs due to a race on increment/decrement of
nr_dirty, see: https://lkml.org/lkml/2014/6/3/648
Fix this by using an atomic_t for nr_dirty.
Reported-by: roma1390@gmail.com
Signed-off-by: Anssi Hannula <anssi.hannula@iki.fi>
Signed-off-by: Joe Thornber <ejt@redhat.com>
Signed-off-by: Mike Snitzer <snitzer@redhat.com>
Signed-off-by: Jiri Slaby <jslaby@suse.cz>
Diffstat (limited to 'kernel')
0 files changed, 0 insertions, 0 deletions