Re: [PATCH 5.10 050/530] md: md_open returns -EBUSY when entering racing area
From: Pavel Machek <hidden>
Date: 2021-05-13 07:59:58
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Hi!
commit 6a4db2a60306eb65bfb14ccc9fde035b74a4b4e7 upstream.
commit d3374825ce57 ("md: make devices disappear when they are no longer
needed.") introduced protection between mddev creating & removing. The
md_open shouldn't create mddev when all_mddevs list doesn't contain
mddev. With currently code logic, there will be very easy to trigger
soft lockup in non-preempt env.
This patch changes md_open returning from -ERESTARTSYS to -EBUSY, which
will break the infinitely retry when md_open enter racing area.
This patch is partly fix soft lockup issue, full fix needs mddev_find
is split into two functions: mddev_find & mddev_find_or_alloc. And
md_open should call new mddev_find (it only does searching job).
For more detail, please refer with Christoph's "split mddev_find" patch
in later commits.Something went wrong here; changelog is truncated, in particular it does not contain required sign-offs. Best regards, Pavel
quoted hunk ↗ jump to hunk
+++ b/drivers/md/md.c@@ -7857,8 +7857,7 @@ static int md_open(struct block_device * /* Wait until bdev->bd_disk is definitely gone */ if (work_pending(&mddev->del_work)) flush_workqueue(md_misc_wq); - /* Then retry the open from the top */ - return -ERESTARTSYS; + return -EBUSY; } BUG_ON(mddev != bdev->bd_disk->private_data);
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