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Wed, 20 Mar 2024 18:42:53 +0900 (JST) (envelope-from penguin-kernel@I-love.SAKURA.ne.jp) Message-ID: <2b75a26f-6c8b-40b3-8ea7-d2cf275b58fe@I-love.SAKURA.ne.jp> Date: Wed, 20 Mar 2024 18:42:52 +0900 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2 1/2] mm,page_owner: Fix refcount imbalance Content-Language: en-US To: Oscar Salvador Cc: Andrew Morton , linux-kernel@vger.kernel.org, linux-mm@kvack.org, Michal Hocko , Vlastimil Babka , Marco Elver , Andrey Konovalov , Alexander Potapenko , syzbot+41bbfdb8d41003d12c0f@syzkaller.appspotmail.com References: <20240319183212.17156-1-osalvador@suse.de> <20240319183212.17156-2-osalvador@suse.de> <20240319162430.3e76504d06f12edc107029a4@linux-foundation.org> From: Tetsuo Handa In-Reply-To: Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 8736DC0025 X-Stat-Signature: rpdqes7d79fmwkpxaswm1fkyuryn1ymo X-Rspam-User: X-HE-Tag: 1710927789-448351 X-HE-Meta: U2FsdGVkX1+FsXRLUeYHggsdU7zj7LmgqeMCKIGiAsxBv8dylB7THEMKYLYSrdRcuyVOaaffj0KjNFRXpsAVP8xTRolS5WrKxyLmJVQocWHLfIS8oqA48lTZ6PKse6JZcLkH3NWE2+ZHSWNkA1K8Hg3iTt2JQxbUjQSSgSmiFHulvaNPOhGyIOapdsLXR8tQuZ9nAG0TExQFKOi6DzXvwbYJyfd316cqmtOYYBViBHqCdCVPNhU6ZFbt7czQyDQFrxGowlZtbASFIe8Ri6hIvNPSFdlz9c2cufwe3mZ6hyI7G3lQlvIQjqOcoIv8Ca3lsc9/1eSC/fMAK44nLA686B+OnNPLWdEbIEbubeKOWpMBcx3NZ8sHE6ltZQxknD9zYJEGvBXQ0ZGiQu/uGyjcQYF3vYi33ttcSI6pkNKEQFlHj3+b/WPUqzGHJ/WnTM9iFXiw9xkLtZJvPgIXlkZ4ILwGaWvP7FJ57dnHm6sEE0CTo6veLScx60Pe3Fi3VR2He8CbNGCs2Nys5heXMJv5Ofs7P0fJZ3wwMlG45nNRWwCMfxmkPSKoYsdYybdDkhyclyV9nqnmRquzl2NVYim12DOKZ8TErPSU8zWRa0/jixnOh9pFAhA3RYQhutBA6WtSU5dGuPq/o/mFd/RbvSbUJmnbnfX8DLqCu1kFjaeSchUDvFK9G+ibDfjgqmRFx4QScXt/HfH6EWxVZjG741JgN2pJLHEMIxOwSLv+gdfukjTdhO+X2zhNFZqdQMESqR4OJ7/eV5bgydqISxApIDKDV/wtycP1D16UTKA+ItlK5Zg3TzNHG3DmTmKag4q82Zwn8ETPswecoksIZt0NGY9yyn0tuD/mihq0Eii4FKdrFP7CIeiTUXTFM62ikRLJVaiVGECFwFJKo4DDd/+Elb/r6pT9SU3C1rJe6qA46HXYiDkecJHEVRzBMLsGJI2qQis8urcdTERFfF8y6bnfn8g 3JEtZbJX onUmLkF2UWAXmXWI6v/H0H6sEBzdw9HmvYNntEsGVTGmfDYvLJ5UEIlFtMG8z3j5SgwA8kCgGC9XLajwSh1RAQxmJi3MQa4nm2W7VxNyWFTLytsD7Q6aotQ+8YjbLovI5abfxXEO/91V9Ig5abtvoIubXb2gBjajnknq1 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: List-Subscribe: List-Unsubscribe: On 2024/03/20 14:49, Oscar Salvador wrote: > This should have the follwing on top: > > diff --git a/mm/page_owner.c b/mm/page_owner.c > index 2613805cb665..e477a71d6adc 100644 > --- a/mm/page_owner.c > +++ b/mm/page_owner.c > @@ -222,8 +222,11 @@ static void dec_stack_record_count(depot_stack_handle_t handle, > { > struct stack_record *stack_record = __stack_depot_get_stack_record(handle); > > - if (stack_record) > - refcount_sub_and_test(nr_base_pages, &stack_record->count); > + if (!stack_record) > + return; > + > + if (refcount_sub_and_test(nr_base_pages, &stack_record->count)) > + WARN(1, "%s refcount went to 0 for %u handle\n", __func__, handle); > } > > That fixed this problem. Thank you. -------- Forwarded Message -------- Date: Wed, 20 Mar 2024 01:31:03 -0700 In-Reply-To: <4362246e-d804-43de-800b-a7840b70919a@I-love.SAKURA.ne.jp> Message-ID: <000000000000410e3b061413692b@google.com> Subject: Re: [syzbot] [mm?] WARNING: refcount bug in __reset_page_owner From: syzbot To: linux-kernel@vger.kernel.org, penguin-kernel@i-love.sakura.ne.jp, syzkaller-bugs@googlegroups.com Hello, syzbot has tested the proposed patch and the reproducer did not trigger any issue: Reported-and-tested-by: syzbot+98c1a1753a0731df2dd4@syzkaller.appspotmail.com Tested on: commit: a4145ce1 Merge tag 'bcachefs-2024-03-19' of https://ev.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=131b1d66180000 kernel config: https://syzkaller.appspot.com/x/.config?x=9f47e8dfa53b0b11 dashboard link: https://syzkaller.appspot.com/bug?extid=98c1a1753a0731df2dd4 compiler: gcc (Debian 12.2.0-14) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 patch: https://syzkaller.appspot.com/x/patch.diff?x=13972985180000 Note: testing is done by a robot and is best-effort only.