linux-ext4 - Re: [PATCH] ext4: Fix lockdep warning when enabling MMP

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Date:   Tue, 11 Apr 2023 15:52:30 +0200
From:   Christian Brauner <brauner@...nel.org>
To:     Jan Kara <jack@...e.cz>
Cc:     Ted Tso <tytso@....edu>, linux-ext4@...r.kernel.org,
        syzbot+aacb82fca60873422114@...kaller.appspotmail.com
Subject: Re: [PATCH] ext4: Fix lockdep warning when enabling MMP

On Tue, Apr 11, 2023 at 02:10:19PM +0200, Jan Kara wrote:
> When we enable MMP in ext4_multi_mount_protect() during mount or
> remount, we end up calling sb_start_write() from write_mmp_block(). This
> triggers lockdep warning because freeze protection ranks above s_umount
> semaphore we are holding during mount / remount. The problem is harmless
> because we are guaranteed the filesystem is not frozen during mount /
> remount but still let's fix the warning by not grabbing freeze
> protection from ext4_multi_mount_protect().
> 
> Reported-by: syzbot+aacb82fca60873422114@...kaller.appspotmail.com
> Signed-off-by: Jan Kara <jack@...e.cz>
> ---

Looks good to me,
Reviewed-by: Christian Brauner <brauner@...nel.org>