This is a note to let you know that I've just added the patch titled
md: md_open returns -EBUSY when entering racing area
to the 5.12-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
md-md_open-returns-ebusy-when-entering-racing-area.patch
and it can be found in the queue-5.12 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 6a4db2a60306eb65bfb14ccc9fde035b74a4b4e7 Mon Sep 17 00:00:00 2001
From: Zhao Heming <heming.zhao@xxxxxxxx>
Date: Sat, 3 Apr 2021 11:01:25 +0800
Subject: md: md_open returns -EBUSY when entering racing area
From: Zhao Heming <heming.zhao@xxxxxxxx>
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.
---
drivers/md/md.c | 3 +--
1 file changed, 1 insertion(+), 2 deletions(-)
--- a/drivers/md/md.c
+++ b/drivers/md/md.c
@@ -7841,8 +7841,7 @@ 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);
Patches currently in stable-queue which might be from heming.zhao@xxxxxxxx are
queue-5.12/md-bitmap-wait-for-external-bitmap-writes-to-complete-during-tear-down.patch
queue-5.12/md-factor-out-a-mddev_find_locked-helper-from-mddev_find.patch
queue-5.12/md-cluster-fix-use-after-free-issue-when-removing-rdev.patch
queue-5.12/md-md_open-returns-ebusy-when-entering-racing-area.patch
