Hi,
在 2023/11/08 5:24, Junxiao Bi 写道:
This reverts commit 5e2cf333b7bd5d3e62595a44d598a254c697cd74.
That commit introduced the following race and can cause system hung.
md_write_start: raid5d:
if (mddev->safemode == 1)
mddev->safemode = 0;
/* sync_checkers is always 0 when writes_pending is in per-cpu mode */
if (mddev->in_sync || mddev->sync_checkers) {
spin_lock(&mddev->lock);
if (mddev->in_sync) {
mddev->in_sync = 0;
set_bit(MD_SB_CHANGE_CLEAN, &mddev->sb_flags);
set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags);
>>> running before md_write_start wake up it
if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING)) {
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, >>>>>>>>>>> hung
!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags),
conf->device_lock);
md_wakeup_thread(mddev->thread);
did_change = 1;
}
spin_unlock(&mddev->lock);
}
Forgot to mention this, above extrem long lines really is not good,
please fix it. I think following should be enough:
raid5d md_write_start
if (mddev->sb_flags & ~(1 << MD_SB_CHANGE_PENDING))
// failed
set_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags)
md_wakeup_thread
wait_event_lock_irq
/*
* wait for MD_SB_CHANGE_PENDING to be cleared, while
* md_write_start expect daemon thread to clear it.
*/
Thanks,
Kuai
...
wait_event(mddev->sb_wait, >>>>>>>>>> hung
!test_bit(MD_SB_CHANGE_PENDING, &mddev->sb_flags) ||
mddev->suspended);
The issue that reverted commit is 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 <junxiao.bi@xxxxxxxxxx>
---
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);
