Re: WARNING in md_ioctl
From: Dae R. Jeong <hidden>
Date: 2020-10-19 07:03:29
Also in:
lkml
Subsystem:
software raid (multiple disks) support, the rest · Maintainers:
Song Liu, Yu Kuai, Linus Torvalds
quoted hunk ↗ jump to hunk
diff --git i/drivers/md/md.c w/drivers/md/md.c index 6072782070230..49442a3f4605b 100644 --- i/drivers/md/md.c +++ w/drivers/md/md.c@@ -7591,8 +7591,10 @@ static int md_ioctl(struct block_device *bdev,fmode_t mode, err = -EBUSY; goto out; } - WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); - set_bit(MD_CLOSING, &mddev->flags); + if (test_and_set_bit(MD_CLOSING, &mddev->flags)) { + err = -EBUSY; + goto out; + } did_set_md_closing = true; mutex_unlock(&mddev->open_mutex); sync_blockdev(bdev); Could you please test whether this fixes the issue?
Since &mddev->open_mutex is held when testing a bit of mddev->flags, I modified the code just a little bit by putting mutex_unlock() as belows.
diff --git a/drivers/md/md.c b/drivers/md/md.c
index 98bac4f304ae..643f7f5be49b 100644
--- a/drivers/md/md.c
+++ b/drivers/md/md.c@@ -7590,8 +7590,11 @@ static int md_ioctl(struct block_device *bdev, fmode_t mode, err = -EBUSY; goto out; } - WARN_ON_ONCE(test_bit(MD_CLOSING, &mddev->flags)); - set_bit(MD_CLOSING, &mddev->flags); + if (test_and_set_bit(MD_CLOSING, &mddev->flags)) { + mutex_unlock(&mddev->open_mutex); + err = -EBUSY; + goto out; + } did_set_md_closing = true; mutex_unlock(&mddev->open_mutex); sync_blockdev(bdev);
The warning no longer recurs (of course, we removed WARN_ON_ONCE()). As I am not familiar with this code, I do not see any other problem. Best regards, Dae R. Jeong