From: Michal Hocko <mhocko@suse.com>
To: Tetsuo Handa <penguin-kernel@i-love.sakura.ne.jp>
Cc: "Mel Gorman" <mgorman@techsingularity.net>,
"Patrick Daly" <quic_pdaly@quicinc.com>,
"David Hildenbrand" <david@redhat.com>,
"Andrew Morton" <akpm@linux-foundation.org>,
syzkaller-bugs@googlegroups.com,
"Ilpo Järvinen" <ilpo.jarvinen@linux.intel.com>,
syzbot <syzbot+223c7461c58c58a4cb10@syzkaller.appspotmail.com>,
linux-mm <linux-mm@kvack.org>
Subject: Re: [PATCH] mm/page_alloc: don't check zonelist_update_seq from atomic allocations
Date: Mon, 3 Apr 2023 10:15:34 +0200 [thread overview]
Message-ID: <ZCqLJqxA9EuPPmAg@dhcp22.suse.cz> (raw)
In-Reply-To: <dfdb9da6-ca8f-7a81-bfdd-d74b4c401f11@I-love.SAKURA.ne.jp>
On Sun 02-04-23 19:48:29, Tetsuo Handa wrote:
> syzbot is reporting circular locking dependency which involves
> zonelist_update_seq seqlock, for zonelist_update_seq is checked
> while doing GFP_ATOMIC allocation.
Could you explain the the deadlock scenario?
> Since zonelist_update_seq is checked for avoiding unnecessary OOM kill,
> there is no need to check zonelist_update_seq for memory allocations
> which will fail without OOM kill.
>
> Therefore, let's keep locking dependency simple, by not checking
> zonelist_update_seq from !__GFP_DIRECT_RECLAIM allocations.
>
> Reported-by: syzbot <syzbot+223c7461c58c58a4cb10@syzkaller.appspotmail.com>
Is this
https://lore.kernel.org/all/0000000000001d74d205f7c1821f@google.com/ the
underlying report ?
> Link: https://syzkaller.appspot.com/bug?extid=223c7461c58c58a4cb10
> Fixes: 3d36424b3b58 ("mm/page_alloc: fix race condition between build_all_zonelists and page allocation")
> Signed-off-by: Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>
--
Michal Hocko
SUSE Labs
next prev parent reply other threads:[~2023-04-03 8:15 UTC|newest]
Thread overview: 20+ messages / expand[flat|nested] mbox.gz Atom feed top
[not found] <000000000000b21f0a05e9ec310d@google.com>
[not found] ` <f6bd471c-f961-ef5e-21c5-bf158be19d12@linux.intel.com>
2023-04-02 10:48 ` Tetsuo Handa
2023-04-03 8:15 ` Michal Hocko [this message]
2023-04-03 11:14 ` Tetsuo Handa
2023-04-03 12:09 ` Michal Hocko
2023-04-03 12:51 ` Tetsuo Handa
2023-04-03 13:44 ` Michal Hocko
2023-04-03 15:12 ` Petr Mladek
2023-04-04 0:37 ` [PATCH] mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock Tetsuo Handa
2023-04-04 2:11 ` Sergey Senozhatsky
2023-04-04 7:43 ` Petr Mladek
2023-04-04 7:54 ` Michal Hocko
2023-04-04 8:20 ` Tetsuo Handa
2023-04-04 11:05 ` Michal Hocko
2023-04-04 11:19 ` Tetsuo Handa
2023-04-04 14:31 ` [PATCH v2] " Tetsuo Handa
2023-04-04 15:20 ` Michal Hocko
2023-04-05 9:02 ` Mel Gorman
2023-04-04 21:25 ` Andrew Morton
2023-04-05 8:28 ` Michal Hocko
2023-04-05 8:53 ` Petr Mladek
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