This is a note to let you know that I've just added the patch titled
dm: don't lock fs when the map is NULL during suspend or resume
to the 6.3-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
dm-don-t-lock-fs-when-the-map-is-null-during-suspend.patch
and it can be found in the queue-6.3 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <sta...@vger.kernel.org> know about it.
commit 514e502e16b737ea99816066abc291911af330e7
Author: Li Lingfeng <lilingfe...@huawei.com>
Date: Thu Jun 1 14:14:23 2023 +0800
dm: don't lock fs when the map is NULL during suspend or resume
[ Upstream commit 2760904d895279f87196f0fa9ec570c79fe6a2e4 ]
As described in commit 38d11da522aa ("dm: don't lock fs when the map is
NULL in process of resume"), a deadlock may be triggered between
do_resume() and do_mount().
This commit preserves the fix from commit 38d11da522aa but moves it to
where it also serves to fix a similar deadlock between do_suspend()
and do_mount(). It does so, if the active map is NULL, by clearing
DM_SUSPEND_LOCKFS_FLAG in dm_suspend() which is called by both
do_suspend() and do_resume().
Fixes: 38d11da522aa ("dm: don't lock fs when the map is NULL in process of
resume")
Signed-off-by: Li Lingfeng <lilingfe...@huawei.com>
Signed-off-by: Mike Snitzer <snit...@kernel.org>
Signed-off-by: Sasha Levin <sas...@kernel.org>
diff --git a/drivers/md/dm-ioctl.c b/drivers/md/dm-ioctl.c
index cc77cf3d41092..7d5c9c582ed2d 100644
--- a/drivers/md/dm-ioctl.c
+++ b/drivers/md/dm-ioctl.c
@@ -1168,13 +1168,10 @@ static int do_resume(struct dm_ioctl *param)
/* Do we need to load a new map ? */
if (new_map) {
sector_t old_size, new_size;
- int srcu_idx;
/* Suspend if it isn't already suspended */
- old_map = dm_get_live_table(md, &srcu_idx);
- if ((param->flags & DM_SKIP_LOCKFS_FLAG) || !old_map)
+ if (param->flags & DM_SKIP_LOCKFS_FLAG)
suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
- dm_put_live_table(md, srcu_idx);
if (param->flags & DM_NOFLUSH_FLAG)
suspend_flags |= DM_SUSPEND_NOFLUSH_FLAG;
if (!dm_suspended_md(md))
diff --git a/drivers/md/dm.c b/drivers/md/dm.c
index dfde0088147a1..0a10e94a6db17 100644
--- a/drivers/md/dm.c
+++ b/drivers/md/dm.c
@@ -2795,6 +2795,10 @@ int dm_suspend(struct mapped_device *md, unsigned int
suspend_flags)
}
map = rcu_dereference_protected(md->map,
lockdep_is_held(&md->suspend_lock));
+ if (!map) {
+ /* avoid deadlock with fs/namespace.c:do_mount() */
+ suspend_flags &= ~DM_SUSPEND_LOCKFS_FLAG;
+ }
r = __dm_suspend(md, map, suspend_flags, TASK_INTERRUPTIBLE,
DMF_SUSPENDED);
if (r)
--
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