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Date:   Tue, 5 Apr 2022 13:45:48 +0200
From:   Michal Hocko <mhocko@suse.com>
To:     Alexander Sverdlin <alexander.sverdlin@nokia.com>
Cc:     Nicholas Piggin <npiggin@gmail.com>,
        Alexander Duyck <alexanderduyck@fb.com>,
        Matthew Wilcox <willy@infradead.org>,
        Hugh Dickins <hughd@google.com>, Yu Zhao <yuzhao@google.com>,
        Mel Gorman <mgorman@techsingularity.net>,
        Lee Schermerhorn <lee.schermerhorn@hp.com>,
        Sasha Levin <sashal@kernel.org>,
        Andrew Morton <akpm@linux-foundation.org>, linux-mm@kvack.org,
        linux-kernel@vger.kernel.org
Subject: Re: mm: swap: locking in release_pages()
Message-ID: <Ykwr7OHllqM+Dpii@dhcp22.suse.cz>
References: <89009285-c75d-0f09-5b08-d133c42a18f9@nokia.com>
 <YkwdRnuQBjoJ01YK@dhcp22.suse.cz>
 <dc5eb22d-5389-bacb-3756-253e774a8394@nokia.com>
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On Tue 05-04-22 13:36:09, Alexander Sverdlin wrote:
> Hello Michal,
> 
> thanks for the quick reply!
> 
> On 05/04/2022 12:43, Michal Hocko wrote:
> >> 1. Crash of v5.4.170 on an ARM32 machine:
> >>
> >> Unable to handle kernel NULL pointer dereference at virtual address 00000104
> >> pgd = e138149d
> >> [00000104] *pgd=84d2fd003, *pmd=8ffd6f003
> >> Internal error: Oops: a07 [#1] PREEMPT SMP ARM
> >> ...
> >> CPU: 1 PID: 6172 Comm: AaSysInfoRColle Tainted: G    B      O      5.4.170-... #1
> >> Hardware name: Keystone
> >> PC is at release_pages+0x194/0x358
> >> LR is at release_pages+0x10c/0x358
> > Which LOC does this correspond to? (faddr2line should give you a nice
> > output).
> 
> Sorry, I forgot this info in the initial report:
> 
> this is indeed the del_page_from_lru_list() in this crash.

Could you be more specific please? Is the problem in list_del or
update_lru_size?

-- 
Michal Hocko
SUSE Labs