linux-kernel - Re: [PATCH 2/2] md: create symlink with disk holder after mddev resume

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Message-ID: <CAPhsuW5ZhW3fR8LwKsMrRV6bVMbXJfonkBqVMVQqw=FAJg3V4A@mail.gmail.com>
Date: Tue, 6 Feb 2024 09:00:47 -0800
From: Song Liu <song@...nel.org>
To: Linux regressions mailing list <regressions@...ts.linux.dev>
Cc: Yu Kuai <yukuai1@...weicloud.com>, linan666@...weicloud.com, 
	linux-raid@...r.kernel.org, linux-kernel@...r.kernel.org, yi.zhang@...wei.com, 
	houtao1@...wei.com, yangerkun@...wei.com, "yukuai (C)" <yukuai3@...wei.com>
Subject: Re: [PATCH 2/2] md: create symlink with disk holder after mddev resume

On Tue, Feb 6, 2024 at 6:46 AM Linux regression tracking (Thorsten
Leemhuis) <regressions@...mhuis.info> wrote:
>
> Hi, Thorsten here, the Linux kernel's regression tracker.
>
> On 21.12.23 09:49, Yu Kuai wrote:
> > 在 2023/12/21 15:11, linan666@...weicloud.com 写道:
> >> From: Li Nan <linan122@...wei.com>
> >>
> >> There is a risk of deadlock when a process gets disk->open_mutex after
> >> suspending mddev, because other processes may hold open_mutex while
> >> submitting io. For example:
> >> [...]
> > Nice catch! This patch looks good except that the new flag
> > 'SymlinkCreated' doesn't look accurate, perhaps 'HolderLinked'
> > will make more sense.
> >
> >> Fix it by getting disk->open_mutex after mddev resume, iterating each
> >> mddev->disk to create symlink for rdev which has not been created yet.
> >> and moving bd_unlink_disk_holder() to mddev_unlock(), rdev has been
> >> deleted from mddev->disks here, which can avoid concurrent bind and
> >> unbind,
> >>
> >> Fixes: 1b0a2d950ee2 ("md: use new apis to suspend array for ioctls
> >> involed array reconfiguration")
>
> Hey, what happened to that patch? It looks a lot like things stalled
> here. I'm asking, because there is a regression report that claims
> 1b0a2d950ee2 to be the culprit that might or might not be causes by the
> problem this patch tries to fix:
> https://bugzilla.kernel.org/show_bug.cgi?id=218459

Thanks for the heads-up. Replied to the thread.

Song