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To: "Kirill A. Shutemov" , Andrew Morton Cc: syzbot , linux-kernel@vger.kernel.org, linux-mm@kvack.org, syzkaller-bugs@googlegroups.com, Matthew Wilcox , Ralph Campbell , David Hildenbrand , Mike Kravetz , Johannes Weiner References: <000000000000bc4fd705a6e090e2@google.com> <0000000000004c38cd05aad1d13f@google.com> <20200720165144.93189f7825bd28e234a42cb8@linux-foundation.org> <20200721111131.bo3g6qkcvbhpupon@black.fi.intel.com> From: Jens Axboe Message-ID: <16e40194-05ac-536b-303f-d2fd31493229@kernel.dk> Date: Tue, 21 Jul 2020 09:11:41 -0600 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:68.0) Gecko/20100101 Thunderbird/68.10.0 MIME-Version: 1.0 In-Reply-To: <20200721111131.bo3g6qkcvbhpupon@black.fi.intel.com> Content-Type: text/plain; charset=utf-8 Content-Language: en-US Content-Transfer-Encoding: 7bit X-Rspamd-Queue-Id: DDCD818103F26 X-Spamd-Result: default: False [0.00 / 100.00] X-Rspamd-Server: rspam03 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 7/21/20 5:11 AM, Kirill A. Shutemov wrote: > On Mon, Jul 20, 2020 at 04:51:44PM -0700, Andrew Morton wrote: >> On Sun, 19 Jul 2020 14:10:19 -0700 syzbot wrote: >> >>> syzbot has found a reproducer for the following issue on: >>> >>> HEAD commit: 4c43049f Add linux-next specific files for 20200716 >>> git tree: linux-next >>> console output: https://syzkaller.appspot.com/x/log.txt?x=12c56087100000 >>> kernel config: https://syzkaller.appspot.com/x/.config?x=2c76d72659687242 >>> dashboard link: https://syzkaller.appspot.com/bug?extid=c48f34012b06c4ac67dd >>> compiler: gcc (GCC) 10.1.0-syz 20200507 >>> syz repro: https://syzkaller.appspot.com/x/repro.syz?x=1344abeb100000 >>> >>> IMPORTANT: if you fix the issue, please add the following tag to the commit: >>> Reported-by: syzbot+c48f34012b06c4ac67dd@syzkaller.appspotmail.com >> >> Thanks. >> >> __handle_mm_fault >> ->pmd_migration_entry_wait >> ->migration_entry_to_page >> >> stumbled onto an unlocked page. >> >> I don't immediately see a cause. Perhaps Matthew's "THP prep patches", >> perhaps something else. >> >> Is it possible to perform a bisection? > > Maybe it's related to the new lock_page_async()? Shouldn't be used for any of those paths at all, though of course can't rule out a bug that triggers it somehow. A bisection would be nice. -- Jens Axboe