linux-kernel - Re: [PATCH] locking/rwsem: Add up_write_non_owner() for percpu_up

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Date:   Wed, 4 Apr 2018 23:14:20 -0400
From:   "Theodore Y. Ts'o" <tytso@....edu>
To:     Waiman Long <longman@...hat.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        Davidlohr Bueso <dave@...olabs.net>,
        Oleg Nesterov <oleg@...hat.com>
Subject: Re: [PATCH] locking/rwsem: Add up_write_non_owner() for
 percpu_up_write()

On Wed, Apr 04, 2018 at 10:37:26AM -0400, Waiman Long wrote:
> The commit 8c5db92a705d ("locking/rwsem: Add DEBUG_RWSEMS to look for
> lock/unlock mismatches") causes a warning in ext4 fstests due to the
> fact that the freeze and thaw ioctls, by design, are run in different
> processes.

While true, it's not just ext4 fstests --- it's any file system which
supports freeze/thaw, since it's happening in the vfs layer.  I have
just as easily replicated the problem using "kvm-xfstests -c xfs
generic/068".  Or "kvm-xfstests -c btrfs generic/068".

Cheers,

						- Ted