linux-kernel - Re: [Customers.Eckelmann] [PATCH] locking/rwsem: Fix up_read_non_owner() warning with DEBUG

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Message-ID: <052d9796f814fc5d6625ac7fcd00dc37b0f11da1.camel@eckelmann.de>
Date:   Wed, 20 Jun 2018 05:49:30 +0000
From:   "Schenk, Gavin" <G.Schenk@...elmann.de>
To:     "tglx@...utronix.de" <tglx@...utronix.de>,
        "longman@...hat.com" <longman@...hat.com>,
        "peterz@...radead.org" <peterz@...radead.org>,
        "mingo@...hat.com" <mingo@...hat.com>
CC:     "dan.j.williams@...el.com" <dan.j.williams@...el.com>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        "u.kleine-koenig@...gutronix.de" <u.kleine-koenig@...gutronix.de>,
        "linux-nfs@...r.kernel.org" <linux-nfs@...r.kernel.org>,
        "arnd@...db.de" <arnd@...db.de>,
        "dave@...olabs.net" <dave@...olabs.net>
Subject: Re: [Customers.Eckelmann] [PATCH] locking/rwsem: Fix
 up_read_non_owner() warning with DEBUG_RWSEMS

Hi,

On Wed, 2018-06-20 at 07:09 +0800, Waiman Long wrote:
> On 05/24/2018 09:26 PM, Waiman Long wrote:
> > It was found that the use of up_read_non_owner() in NFS was causing
> > the following warning when DEBUG_RWSEMS was configured.
> > 
> >   DEBUG_LOCKS_WARN_ON(sem->owner != ((struct task_struct *)(1UL << 0)))
> > 
> > Looking into the rwsem.c file, it was discovered that the corresponding
> > down_read_non_owner() function was not setting the owner field properly.
> > This is fixed now, and the warning should be gone.
> > 
> > Signed-off-by: Waiman Long <longman@...hat.com>
Tested-by: Gavin Schenk <g.schenk@...elmann.de>

This fixes my reproducible locking splat when booting with nfsroot and changing password. Thank you!

Regards
Gavin Schenk