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Subject: Re: linux-5.13.2: warning from kernel/rcu/tree_plugin.h:359
To:     Greg KH <gregkh@linuxfoundation.org>,
        Matthew Wilcox <willy@infradead.org>
CC:     Zhouyi Zhou <zhouzhouyi@gmail.com>,
        Chris Clayton <chris2553@googlemail.com>,
        Oleksandr Natalenko <oleksandr@natalenko.name>,
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        <stable@vger.kernel.org>, Chris Rankin <rankincj@gmail.com>,
        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 <rcu@vger.kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>,
        Linux-MM <linux-mm@kvack.org>,
        "Huang, Ying" <ying.huang@intel.com>
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From:   Miaohe Lin <linmiaohe@huawei.com>
Message-ID: <01fef2db-bd7e-12b6-ec21-2addd02e7062@huawei.com>
Date:   Fri, 23 Jul 2021 09:51:09 +0800
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On 2021/7/22 22:00, Greg KH wrote:
> On Thu, Jul 22, 2021 at 03:26:52PM +0200, Greg KH wrote:
>> On Thu, Jul 22, 2021 at 01:36:02PM +0100, Matthew Wilcox wrote:
>>> On Thu, Jul 22, 2021 at 04:57:57PM +0800, Zhouyi Zhou wrote:
>>>> Thanks for reviewing,
>>>>
>>>> What I have deduced from the dmesg  is:
>>>> In function do_swap_page,
>>>> after invoking
>>>> 3385        si = get_swap_device(entry); /* rcu_read_lock */
>>>> and before
>>>> 3561    out:
>>>> 3562        if (si)
>>>> 3563            put_swap_device(si);
>>>> The thread got scheduled out in
>>>> 3454        locked = lock_page_or_retry(page, vma->vm_mm, vmf->flags);
>>>>
>>>> I am only familiar with Linux RCU subsystem, hope mm people can solve our
>>>> confusions.
>>>
>>> I don't understamd why you're still talking.  The problem is understood.
>>> You need to revert the unnecessary backport of 2799e77529c2 and
>>> 2efa33fc7f6e
>>
>> Sorry for the delay, will go do so in a minute...
> 
> Both now reverted from 5.10.y and 5.13.y.
> 

I browsed my previous backport notifying email and found that these two patches are also
backported into 5.12. And it seems it's missed.

Thanks.

> thanks,
> 
> greg k-h
> .
>