Minki/linux
1
0
Fork 1
mirror of https://github.com/torvalds/linux.git synced 2024-12-14 07:02:23 +00:00
Code Issues Packages Projects Releases Wiki Activity

md: Notify sysfs sync_completed in md_reap_sync_thread()

Browse Source 
The mdadm test 07layouts randomly produces a kernel hung task deadlock.
The deadlock is caused by the suspend_lo/suspend_hi files being set by
the mdadm background process during reshape and not being cleared
because the process hangs. (Leaving aside the issue of the fragility of
freezing kernel tasks by buggy userspace processes...)

When the background mdadm process hangs it, is waiting (without a
timeout) on a change to the sync_completed file signalling that the
reshape has completed. The process is woken up a couple times when
the reshape finishes but it is woken up before MD_RECOVERY_RUNNING
is cleared so sync_completed_show() reports 0 instead of "none".

To fix this, notify the sysfs file in md_reap_sync_thread() after
MD_RECOVERY_RUNNING has been cleared. This wakes up mdadm and causes
it to continue and write to suspend_lo/suspend_hi to allow IO to
continue.

Signed-off-by: Logan Gunthorpe <logang@deltatee.com>
Reviewed-by: Christoph Hellwig <hch@lst.de>
Signed-off-by: Song Liu <song@kernel.org>
Signed-off-by: Jens Axboe <axboe@kernel.dk>
This commit is contained in:
Logan Gunthorpe 2022-06-08 10:27:56 -06:00 committed by Jens Axboe
parent b368856aab
commit 9973f0fa7d
1 changed files with 1 additions and 0 deletions
Show Stats Download Patch File Download Diff File Expand all files Collapse all files

1
drivers/md/md.c
View File

@ -9472,6 +9472,7 @@ void md_reap_sync_thread(struct mddev *mddev)
wake_up(&resync_wait);
/* flag recovery needed just to double check */
set_bit(MD_RECOVERY_NEEDED, &mddev->recovery);
sysfs_notify_dirent_safe(mddev->sysfs_completed);
sysfs_notify_dirent_safe(mddev->sysfs_action);
md_new_event();
if (mddev->event_work.func)