Re: [PATCH V3 2/2] Revert "md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d"
From: Yu Kuai <hidden>
Date: 2023-11-09 06:28:30
在 2023/11/09 2:22, Junxiao Bi 写道:
This reverts commit 5e2cf333b7bd5d3e62595a44d598a254c697cd74.
That commit introduced the following race and can cause system hung.
md_write_start: raid5d:
// mddev->in_sync == 1
set "MD_SB_CHANGE_PENDING"
// running before md_write_start wakeup it
waiting "MD_SB_CHANGE_PENDING" cleared
>>>>>>>>> hung
wakeup mddev->thread
...
waiting "MD_SB_CHANGE_PENDING" cleared
>>>> hung, raid5d should clear this flag
but get hung by same flag.
The issue reverted commit fixing is fixed by last patch in a new way.
Fixes: 5e2cf333b7bd ("md/raid5: Wait for MD_SB_CHANGE_PENDING in raid5d")
Signed-off-by: Junxiao Bi <redacted>LGTM Reviewed-by: Yu Kuai <redacted>
quoted hunk ↗ jump to hunk
--- drivers/md/raid5.c | 12 ------------ 1 file changed, 12 deletions(-)diff --git a/drivers/md/raid5.c b/drivers/md/raid5.c index dc031d42f53b..fcc8a44dd4fd 100644 --- a/drivers/md/raid5.c +++ b/drivers/md/raid5.c@@ -36,7 +36,6 @@ */ #include <linux/blkdev.h> -#include <linux/delay.h> #include <linux/kthread.h> #include <linux/raid/pq.h> #include <linux/async_tx.h>@@ -6820,18 +6819,7 @@ static void raid5d(struct md_thread *thread) spin_unlock_irq(&conf->device_lock); md_check_recovery(mddev); spin_lock_irq(&conf->device_lock); - - /* - * Waiting on MD_SB_CHANGE_PENDING below may deadlock - * seeing md_check_recovery() is needed to clear - * the flag when using mdmon. - */ - continue; } - - wait_event_lock_irq(mddev->sb_wait, - !test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags), - conf->device_lock); } pr_debug("%d stripes handled\n", handled);