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Tue, 02 Jul 2019 09:01:12 -0700 (PDT) Received: from desktop-bart.svl.corp.google.com ([2620:15c:2cd:202:4308:52a3:24b6:2c60]) by smtp.gmail.com with ESMTPSA id q198sm22380266pfq.155.2019.07.02.09.01.11 (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Tue, 02 Jul 2019 09:01:11 -0700 (PDT) Subject: Re: INFO: task hung in blkdev_issue_flush (2) To: syzbot , axboe@kernel.dk, idryomov@gmail.com, linux-block@vger.kernel.org, linux-kernel@vger.kernel.org, sagi@grimberg.me, snitzer@redhat.com, syzkaller-bugs@googlegroups.com, torvalds@linux-foundation.org, wgh@torlan.ru, zkabelac@redhat.com References: <0000000000009c93d5058cb46073@google.com> From: Bart Van Assche Message-ID: <6a853698-6244-7c4e-77cd-73e4fd672376@acm.org> Date: Tue, 2 Jul 2019 09:01:10 -0700 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.1 MIME-Version: 1.0 In-Reply-To: <0000000000009c93d5058cb46073@google.com> Content-Type: text/plain; charset=utf-8; format=flowed Content-Language: en-US Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 7/2/19 8:27 AM, syzbot wrote: > Showing all locks held in the system: > 1 lock held by khungtaskd/1043: >  #0: 00000000f7c610b3 (rcu_read_lock){....}, at: > debug_show_all_locks+0x5f/0x27e kernel/locking/lockdep.c:5149 > 2 locks held by rsyslogd/8451: >  #0: 00000000dfc1566f (&f->f_pos_lock){+.+.}, at: > __fdget_pos+0xee/0x110 fs/file.c:801 >  #1: 0000000054220207 (&rq->lock){-.-.}, at: rq_lock > kernel/sched/sched.h:1168 [inline] >  #1: 0000000054220207 (&rq->lock){-.-.}, at: __schedule+0x1f5/0x1560 > kernel/sched/core.c:3397 > 2 locks held by getty/8541: >  #0: 000000004ff543bd (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 000000002a3905f3 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8542: >  #0: 000000006e67fcec (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 00000000ee71e4f3 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8543: >  #0: 00000000bd0907a0 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 000000000876abce (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8544: >  #0: 00000000710d6f7d (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 00000000af289586 (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8545: >  #0: 000000003399e62d (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 00000000ee97f91a (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8546: >  #0: 00000000ff2274c6 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 00000000b96c5a9f (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 > 2 locks held by getty/8547: >  #0: 000000005165f028 (&tty->ldisc_sem){++++}, at: > ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:341 >  #1: 00000000e89d5b4a (&ldata->atomic_read_lock){+.+.}, at: > n_tty_read+0x232/0x1b70 drivers/tty/n_tty.c:2156 Since the tty layer does not call any block layer code, does this mean that the root cause is in the tty code instead of in the block layer? Bart.