linux-kernel - Re: [PATCH] PM: hibernate: Fix the exclusive get block device in test

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Message-ID: <CAJZ5v0hV7UFSz=REyVDuy90tW7k9NyBme-S8mEuHSRpEySAcuQ@mail.gmail.com>
Date:   Wed, 23 Aug 2023 14:44:32 +0200
From:   "Rafael J. Wysocki" <rafael@...nel.org>
To:     Chen Yu <yu.c.chen@...el.com>
Cc:     "Rafael J. Wysocki" <rafael@...nel.org>,
        Len Brown <len.brown@...el.com>, Pavel Machek <pavel@....cz>,
        linux-pm@...r.kernel.org, linux-kernel@...r.kernel.org,
        Chenzhou Feng <chenzhoux.feng@...el.com>,
        syzbot+38d04642cea49f3a3d2e@...kaller.appspotmail.com
Subject: Re: [PATCH] PM: hibernate: Fix the exclusive get block device in
 test_resume mode

On Wed, Aug 23, 2023 at 10:19 AM Chen Yu <yu.c.chen@...el.com> wrote:
>
> commit 5904de0d735b ("PM: hibernate: Do not get block device exclusively
> in test_resume mode") fixes a hibernation issue under test_resume mode.
> That commit is supposed to open the block device in non-exclusive mode
> when in test_resume. However the code did the opposite, which is against
> its description.
>
> Fix this by really disabling exclusive mode under test_resume.
>
> Reported-by: syzbot+38d04642cea49f3a3d2e@...kaller.appspotmail.com
> Closes: https://lore.kernel.org/lkml/000000000000761f5f0603324129@google.com/
> Fixes: 5904de0d735b ("PM: hibernate: Do not get block device exclusively in test_resume mode")
> Signed-off-by: Chen Yu <yu.c.chen@...el.com>
> ---
>  kernel/power/swap.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
>
> diff --git a/kernel/power/swap.c b/kernel/power/swap.c
> index f6ebcd00c410..c12b34dd529c 100644
> --- a/kernel/power/swap.c
> +++ b/kernel/power/swap.c
> @@ -1518,7 +1518,7 @@ static void *swsusp_holder;
>
>  int swsusp_check(bool snapshot_test)
>  {
> -       void *holder = snapshot_test ? &swsusp_holder : NULL;
> +       void *holder = snapshot_test ? NULL : &swsusp_holder;
>         int error;
>
>         hib_resume_bdev = blkdev_get_by_dev(swsusp_resume_device, BLK_OPEN_READ,
> @@ -1573,7 +1573,7 @@ void swsusp_close(bool snapshot_test)
>                 return;
>         }
>
> -       blkdev_put(hib_resume_bdev, snapshot_test ? &swsusp_holder : NULL);
> +       blkdev_put(hib_resume_bdev, snapshot_test ? NULL : &swsusp_holder);
>  }
>
>  /**
> --

Applied as 6.6 material, thanks!