Re: [PATCH v2] dm-raid: Fix WARN_ON_ONCE check for sync_thread in raid_resume

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Hi,

在 2024/06/13 2:12, Benjamin Marzinski 写道:
rm-raid devices will occasionally trigger the following warning when
dm-raid

being resumed after a table load because DM_RECOVERY_RUNNING is set:

WARNING: CPU: 7 PID: 5660 at drivers/md/dm-raid.c:4105 raid_resume+0xee/0x100 [dm_raid]

The failing check is:
WARN_ON_ONCE(test_bit(MD_RECOVERY_RUNNING, &mddev->recovery));

This check is designed to make sure that the sync thread isn't
registered, but md_check_recovery can set MD_RECOVERY_RUNNING without
the sync_thread ever getting registered. Instead of checking if
MD_RECOVERY_RUNNING is set, check if sync_thread is non-NULL.

Fixes: 16c4770c75b1 ("dm-raid: really frozen sync_thread during suspend")
Suggested-by: Yu Kuai <yukuai1@xxxxxxxxxxxxxxx>
Please use the address yukuai3@xxxxxxxxxx

Signed-off-by: Benjamin Marzinski <bmarzins@xxxxxxxxxx>
---
Changes in v2:
  - Move mddev_lock_nointr() earlier to protect dereference and use
    rcu_dereference_protected() to access sync_thread

  drivers/md/dm-raid.c | 5 +++--
  1 file changed, 3 insertions(+), 2 deletions(-)

diff --git a/drivers/md/dm-raid.c b/drivers/md/dm-raid.c
index abe88d1e6735..b149ac46a990 100644
--- a/drivers/md/dm-raid.c
+++ b/drivers/md/dm-raid.c
@@ -4101,10 +4101,11 @@ static void raid_resume(struct dm_target *ti)
  		if (mddev->delta_disks < 0)
  			rs_set_capacity(rs);
+ mddev_lock_nointr(mddev);
  		WARN_ON_ONCE(!test_bit(MD_RECOVERY_FROZEN, &mddev->recovery));
-		WARN_ON_ONCE(test_bit(MD_RECOVERY_RUNNING, &mddev->recovery));
+		WARN_ON_ONCE(rcu_dereference_protected(mddev->sync_thread,
+						       lockdep_is_held(&mddev->reconfig_mutex)));
  		clear_bit(RT_FLAG_RS_FROZEN, &rs->runtime_flags);
-		mddev_lock_nointr(mddev);

Other than the typo, LGTM

Suggested-and-reviewed-by: Yu Kuai <yukuai3@xxxxxxxxxx>
  		mddev->ro = 0;
  		mddev->in_sync = 0;
  		md_unfrozen_sync_thread(mddev);






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