linux-kernel - Re: [PATCH v5 06/14] md: fix missing release of 'active

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Message-ID: <CAPhsuW51gFwRdCNmoLuwmCuofAKetV2-gj-5Hb3fNGgu+5yUyA@mail.gmail.com>
Date: Wed, 7 Feb 2024 23:47:52 -0800
From: Song Liu <song@...nel.org>
To: Yu Kuai <yukuai1@...weicloud.com>
Cc: mpatocka@...hat.com, heinzm@...hat.com, xni@...hat.com, 
	blazej.kucman@...ux.intel.com, agk@...hat.com, snitzer@...nel.org, 
	dm-devel@...ts.linux.dev, yukuai3@...wei.com, jbrassow@....redhat.com, 
	neilb@...e.de, shli@...com, akpm@...l.org, linux-kernel@...r.kernel.org, 
	linux-raid@...r.kernel.org, yi.zhang@...wei.com, yangerkun@...wei.com
Subject: Re: [PATCH v5 06/14] md: fix missing release of 'active_io' for flush

On Thu, Feb 1, 2024 at 1:30 AM Yu Kuai <yukuai1@...weicloud.com> wrote:
>
> From: Yu Kuai <yukuai3@...wei.com>
>
> submit_flushes
>  atomic_set(&mddev->flush_pending, 1);
>  rdev_for_each_rcu(rdev, mddev)
>   atomic_inc(&mddev->flush_pending);
>   bi->bi_end_io = md_end_flush
>   submit_bio(bi);
>                         /* flush io is done first */
>                         md_end_flush
>                          if (atomic_dec_and_test(&mddev->flush_pending))
>                           percpu_ref_put(&mddev->active_io)
>                           -> active_io is not released
>
>  if (atomic_dec_and_test(&mddev->flush_pending))
>   -> missing release of active_io
>
> For consequence, mddev_suspend() will wait for 'active_io' to be zero
> forever.
>
> Fix this problem by releasing 'active_io' in submit_flushes() if
> 'flush_pending' is decreased to zero.
>
> Fixes: fa2bbff7b0b4 ("md: synchronize flush io with array reconfiguration")
> Reported-by: Blazej Kucman <blazej.kucman@...ux.intel.com>
> Closes: https://lore.kernel.org/lkml/20240130172524.0000417b@linux.intel.com/
> Signed-off-by: Yu Kuai <yukuai3@...wei.com>

Applied this patch to md-6.8.

Thanks,
Song