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bh=zpcFZhnkXNejYUU3GeXml5SpleKhC+q8AUtQ+vmZs8g=; b=emKtkaODoxFMfSrdvbQy1RWSDVObi9qFMEGhwgUfU60zrEAhIHSQOZg8zLqwv2slpqhqru pJKqdaVtMjUX7uXehBKilbxAyQT7TgKRUzfXuKKI4pzLnJWXiXhmkEk5QBloo6ECXG6ANS qjliVtwIUQtSvviKHqaLRw3rKPfrCEc= Received: from imap2.suse-dmz.suse.de (imap2.suse-dmz.suse.de [192.168.254.74]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (P-521) server-digest SHA512) (No client certificate requested) by imap2.suse-dmz.suse.de (Postfix) with ESMTPS id B315313A10; Wed, 5 Apr 2023 08:28:08 +0000 (UTC) Received: from dovecot-director2.suse.de ([192.168.254.65]) by imap2.suse-dmz.suse.de with ESMTPSA id trVZKRgxLWTtQQAAMHmgww (envelope-from ); Wed, 05 Apr 2023 08:28:08 +0000 Date: Wed, 5 Apr 2023 10:28:07 +0200 From: Michal Hocko To: Andrew Morton Cc: Tetsuo Handa , Petr Mladek , Patrick Daly , Mel Gorman , David Hildenbrand , Sergey Senozhatsky , Steven Rostedt , John Ogness , syzkaller-bugs@googlegroups.com, Ilpo =?iso-8859-1?Q?J=E4rvinen?= , syzbot , linux-mm Subject: Re: [PATCH v2] mm/page_alloc: fix potential deadlock on zonelist_update_seq seqlock Message-ID: References: <78ff6e70-e986-1fcb-eafb-3edd5f2bceae@I-love.SAKURA.ne.jp> <6266b161-e4c3-7d65-6590-da6cc04d93ec@I-love.SAKURA.ne.jp> <0585ddb9-5de8-8cdd-202e-53887bbb6b5f@I-love.SAKURA.ne.jp> <8796b95c-3da3-5885-fddd-6ef55f30e4d3@I-love.SAKURA.ne.jp> <20230404142528.d232bcdc59ac9cf11de10580@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20230404142528.d232bcdc59ac9cf11de10580@linux-foundation.org> X-Rspam-User: X-Rspamd-Server: rspam03 X-Stat-Signature: akd8fu15x6s3zfiutaiox9fwx87ry19w X-Rspamd-Queue-Id: 7FCBD120010 X-HE-Tag: 1680683290-419780 X-HE-Meta: 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 U1Lz27KM GhVI+d/OjOSRd5p7LuTS1OIaNAyh+9wcN98ykoZzB1lfh1Aj/sI0p3/0aYij2YCBlJc3wrfYngOgAcmxupg3DPT7Pz9wiW3xkYDlHcEI+bQWS14lnuH+KqnC2raUJJG1PEP+M22UCnGRlVfuv2wIhRM2gG09oLmir6AnT+ygHeefT5SrH13f6KiejEKV9vzfo0gIacoDyQsAZDLHHWw4VdBUXoLQlC+pG7HSoS8TYPEKzdnXg6OcCpjYVKZvAG2aD+kEksYQE3sNBKKejUDvhcIAKOhLyo2erjV4ZZLB11MxY8DPcYewBHzdUkg== X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue 04-04-23 14:25:28, Andrew Morton wrote: > On Tue, 4 Apr 2023 23:31:58 +0900 Tetsuo Handa wrote: > > > syzbot is reporting circular locking dependency which involves > > zonelist_update_seq seqlock [1], for this lock is checked by memory > > allocation requests which do not need to be retried. > > I queued this, along with a note that an updated changelog is likely. > > Do we feel that a -stable backport is warranted? I think so, from your > earlier comments. Please add the cc:stable to the changelog in this > situation. Memory hotplug is pretty rare event so the deadlock is quite unlikely. On the other hand the fix is pretty easy so it shouldn't hurt to have it in stable kernels. -- Michal Hocko SUSE Labs