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;
Subject: Re: linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359
To:     Matthew Wilcox <willy@infradead.org>,
        Oleksandr Natalenko <oleksandr@natalenko.name>
Cc:     linux-kernel@vger.kernel.org, stable@vger.kernel.org,
        Chris Rankin <rankincj@gmail.com>,
        "Paul E. McKenney" <paulmck@kernel.org>,
        Josh Triplett <josh@joshtriplett.org>,
        Steven Rostedt <rostedt@goodmis.org>,
        Mathieu Desnoyers <mathieu.desnoyers@efficios.com>,
        Lai Jiangshan <jiangshanlai@gmail.com>,
        Joel Fernandes <joel@joelfernandes.org>, rcu@vger.kernel.org,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org
References: <c9fd1311-662c-f993-c8ef-54af036f2f78@googlemail.com>
 <2245518.LNIG0phfVR@natalenko.name> <6698965.kvI7vG0SvZ@natalenko.name>
 <YPSbjXrBYsRZagAv@casper.infradead.org>
From:   Chris Clayton <chris2553@googlemail.com>
Message-ID: <f2a2c82b-bd5b-5ddb-1be5-4b5dcab5daf6@googlemail.com>
Date:   Sun, 18 Jul 2021 22:36:36 +0100
User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:78.0) Gecko/20100101
 Thunderbird/78.12.0
MIME-Version: 1.0
In-Reply-To: <YPSbjXrBYsRZagAv@casper.infradead.org>
Content-Type: text/plain; charset=utf-8
Content-Language: en-GB
Content-Transfer-Encoding: 8bit
Precedence: bulk


On 18/07/2021 22:22, Matthew Wilcox wrote:
> On Sun, Jul 18, 2021 at 11:03:51PM +0200, Oleksandr Natalenko wrote:
>> + stable@vger.kernel.org
>>
>> On neděle 18. července 2021 23:01:24 CEST Oleksandr Natalenko wrote:
>>> Hello.
>>>
>>> On sobota 17. července 2021 22:22:08 CEST Chris Clayton wrote:
>>>> I checked the output from dmesg yesterday and found the following warning:
>>>>
>>>> [Fri Jul 16 09:15:29 2021] ------------[ cut here ]------------
>>>> [Fri Jul 16 09:15:29 2021] WARNING: CPU: 11 PID: 2701 at
>>>> kernel/rcu/tree_plugin.h:359 rcu_note_context_switch+0x37/0x3d0 [Fri Jul
> 
> Could you run ./scripts/faddr2line vmlinux rcu_note_context_switch+0x37/0x3d0
> 
$ ./scripts/faddr2line vmlinux rcu_note_context_switch+0x37/0x3d0
rcu_note_context_switch+0x37/0x3d0:
rcu_note_context_switch at ??:?

>>>> [Fri Jul 16 09:15:29 2021] Call Trace:
>>>> [Fri Jul 16 09:15:29 2021]  __schedule+0x86/0x810
>>>> [Fri Jul 16 09:15:29 2021]  schedule+0x40/0xe0
>>>> [Fri Jul 16 09:15:29 2021]  io_schedule+0x3d/0x60
>>>> [Fri Jul 16 09:15:29 2021]  wait_on_page_bit_common+0x129/0x390
>>>> [Fri Jul 16 09:15:29 2021]  ? __filemap_set_wb_err+0x10/0x10
>>>> [Fri Jul 16 09:15:29 2021]  __lock_page_or_retry+0x13f/0x1d0
>>>> [Fri Jul 16 09:15:29 2021]  do_swap_page+0x335/0x5b0
>>>> [Fri Jul 16 09:15:29 2021]  __handle_mm_fault+0x444/0xb20
>>>> [Fri Jul 16 09:15:29 2021]  handle_mm_fault+0x5c/0x170
> 
> You were handling a page fault at the time.  The page you wanted was
> on swap and this warning fired as a result of waiting for the page
> to come back in from swap.  There are a number of warnings in that
> function, so it'd be good to track down exactly which one it is.
>