linux-kernel - Re: [RFC PATCH v2 2/2] locking/percpu-rwsem: Mark rwsem as non-spinnable in percpu_rwsem

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Message-ID: <bf390812-6fbe-97d9-040a-70eba61b3d81@redhat.com>
Date:   Tue, 15 May 2018 09:45:22 -0400
From:   Waiman Long <longman@...hat.com>
To:     Amir Goldstein <amir73il@...il.com>
Cc:     Ingo Molnar <mingo@...hat.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Thomas Gleixner <tglx@...utronix.de>,
        linux-kernel <linux-kernel@...r.kernel.org>,
        linux-fsdevel <linux-fsdevel@...r.kernel.org>,
        Davidlohr Bueso <dave@...olabs.net>,
        "Theodore Y. Ts'o" <tytso@....edu>,
        Oleg Nesterov <oleg@...hat.com>, Jan Kara <jack@...e.cz>
Subject: Re: [RFC PATCH v2 2/2] locking/percpu-rwsem: Mark rwsem as
 non-spinnable in percpu_rwsem_release()

On 05/15/2018 01:42 AM, Amir Goldstein wrote:
> On Mon, May 14, 2018 at 10:31 PM, Waiman Long <longman@...hat.com> wrote:
>> The percpu_rwsem_release() is called when the ownership of the embedded
>> rwsem is to be transferred to another task. The new owner, however, may
>> take a while to get the ownership of the lock via percpu_rwsem_acquire().
>> During that period, the rwsem is now marked as writer-owned with no
>> optimistic spinning.
>>
> Waiman,
>
> Thanks for the fix. I will test it soon.
>
> For this commit message I suggest that you add parts of the reproducer
> found here:
> https://marc.info/?l=linux-fsdevel&m=152622016219975&w=2
>
> Thanks,
> Amir.
Sure. I will add that to the commit log.

Cheers,
Longman