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    SubjectRe: [PATCH 5.10 050/530] md: md_open returns -EBUSY when entering racing area
    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

    > +++ 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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