Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18;
Date:   Fri, 15 Oct 2021 12:20:30 +0200
From:   Peter Zijlstra <peterz@infradead.org>
To:     Yanfei Xu <yanfei.xu@windriver.com>
Cc:     mingo@redhat.com, will@kernel.org, longman@redhat.com,
        boqun.feng@gmail.com, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2 2/3] locking/rwsem: disable preemption for spinning
 region
Message-ID: <YWlV7gVnPColm61C@hirez.programming.kicks-ass.net>
References: <20211013134154.1085649-1-yanfei.xu@windriver.com>
 <20211013134154.1085649-3-yanfei.xu@windriver.com>
 <YWlUZ5BlUZRA7LGR@hirez.programming.kicks-ass.net>
MIME-Version: 1.0
Content-Type: text/plain; charset=us-ascii
Content-Disposition: inline
In-Reply-To: <YWlUZ5BlUZRA7LGR@hirez.programming.kicks-ass.net>
Precedence: bulk

On Fri, Oct 15, 2021 at 12:13:59PM +0200, Peter Zijlstra wrote:
> On Wed, Oct 13, 2021 at 09:41:53PM +0800, Yanfei Xu wrote:
> > The spinning region rwsem_spin_on_owner() should not be preempted,
> > however the rwsem_down_write_slowpath() invokes it and don't disable
> > preemption. Fix it by adding a pair of preempt_disable/enable().
> 
> I'm thinking we should do this patch before #1, otherwise we have a
> single patch window where we'll trigger the assertion, no?

Anyway, I've stuck the lot (reordered) into my locking/core branch, lets
see what the robots make of it ;-)