linux-kernel - [syzbot] INFO: task hung in blk_mq_freeze

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Message-ID: <0000000000003728d105d13b90c7@google.com>
Date:   Sat, 20 Nov 2021 09:17:16 -0800
From:   syzbot <syzbot+8ea6cf15ac5b5bb2f600@...kaller.appspotmail.com>
To:     catalin.marinas@....com, linux-arm-kernel@...ts.infradead.org,
        linux-kernel@...r.kernel.org, mark.rutland@....com, maz@...nel.org,
        pcc@...gle.com, peterz@...radead.org,
        syzkaller-bugs@...glegroups.com, will@...nel.org
Subject: [syzbot] INFO: task hung in blk_mq_freeze_queue (2)

Hello,

syzbot found the following issue on:

HEAD commit:    a90af8f15bdc Merge tag 'libata-5.16-rc2' of git://git.kern..
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=17d9e6deb00000
kernel config:  https://syzkaller.appspot.com/x/.config?x=b128da186442e627
dashboard link: https://syzkaller.appspot.com/bug?extid=8ea6cf15ac5b5bb2f600
compiler:       aarch64-linux-gnu-gcc (Debian 10.2.1-6) 10.2.1 20210110, GNU ld (GNU Binutils for Debian) 2.35.1
userspace arch: arm

Unfortunately, I don't have any reproducer for this issue yet.

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+8ea6cf15ac5b5bb2f600@...kaller.appspotmail.com

INFO: task syz-executor.0:11597 blocked for more than 430 seconds.
      Not tainted 5.16.0-rc1-syzkaller-00313-ga90af8f15bdc #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:    0 pid:11597 ppid:  2194 flags:0x00400001
Call trace:
 __switch_to+0x274/0x3b4 arch/arm64/kernel/process.c:526
 context_switch kernel/sched/core.c:4972 [inline]
 __schedule+0x818/0x1be0 kernel/sched/core.c:6253
 schedule+0xb8/0x224 kernel/sched/core.c:6326
 blk_mq_freeze_queue_wait+0xf4/0x130 block/blk-mq.c:178
 blk_freeze_queue block/blk-mq.c:205 [inline]
 blk_mq_freeze_queue+0x20/0x30 block/blk-mq.c:214
 nbd_add_socket+0x134/0x690 drivers/block/nbd.c:1109
 __nbd_ioctl drivers/block/nbd.c:1454 [inline]
 nbd_ioctl+0x42c/0x8f0 drivers/block/nbd.c:1511
 compat_blkdev_ioctl+0x774/0x9a0 block/ioctl.c:674
 __do_compat_sys_ioctl fs/ioctl.c:972 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:914 [inline]
 __arm64_compat_sys_ioctl+0x1d0/0x220 fs/ioctl.c:914
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
 el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
 do_el0_svc_compat+0x40/0x80 arch/arm64/kernel/syscall.c:187
 el0_svc_compat+0x64/0x290 arch/arm64/kernel/entry-common.c:736
 el0t_32_sync_handler+0x90/0x140 arch/arm64/kernel/entry-common.c:746
 el0t_32_sync+0x1a4/0x1a8 arch/arm64/kernel/entry.S:577
INFO: task syz-executor.0:11605 blocked for more than 430 seconds.
      Not tainted 5.16.0-rc1-syzkaller-00313-ga90af8f15bdc #0
"echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
task:syz-executor.0  state:D stack:    0 pid:11605 ppid:  2194 flags:0x00400001
Call trace:
 __switch_to+0x274/0x3b4 arch/arm64/kernel/process.c:526
 context_switch kernel/sched/core.c:4972 [inline]
 __schedule+0x818/0x1be0 kernel/sched/core.c:6253
 schedule+0xb8/0x224 kernel/sched/core.c:6326
 schedule_preempt_disabled+0x18/0x30 kernel/sched/core.c:6385
 __mutex_lock_common kernel/locking/mutex.c:680 [inline]
 __mutex_lock+0x3c0/0x7ec kernel/locking/mutex.c:740
 mutex_lock_nested+0x78/0x100 kernel/locking/mutex.c:792
 nbd_ioctl+0x108/0x8f0 drivers/block/nbd.c:1504
 compat_blkdev_ioctl+0x774/0x9a0 block/ioctl.c:674
 __do_compat_sys_ioctl fs/ioctl.c:972 [inline]
 __se_compat_sys_ioctl fs/ioctl.c:914 [inline]
 __arm64_compat_sys_ioctl+0x1d0/0x220 fs/ioctl.c:914
 __invoke_syscall arch/arm64/kernel/syscall.c:38 [inline]
 invoke_syscall+0x6c/0x260 arch/arm64/kernel/syscall.c:52
 el0_svc_common.constprop.0+0xc4/0x254 arch/arm64/kernel/syscall.c:142
 do_el0_svc_compat+0x40/0x80 arch/arm64/kernel/syscall.c:187
 el0_svc_compat+0x64/0x290 arch/arm64/kernel/entry-common.c:736
 el0t_32_sync_handler+0x90/0x140 arch/arm64/kernel/entry-common.c:746
 el0t_32_sync+0x1a4/0x1a8 arch/arm64/kernel/entry.S:577

Showing all locks held in the system:
1 lock held by khungtaskd/27:
 #0: ffff800015e18f20 (rcu_read_lock){....}-{1:2}, at: debug_show_all_locks+0x74/0x25c kernel/locking/lockdep.c:6460
1 lock held by syslogd/1983:
1 lock held by klogd/1987:
2 locks held by getty/2147:
 #0: ffff000013dc7098 (&tty->ldisc_sem){++++}-{0:0}, at: ldsem_down_read+0x3c/0x50 drivers/tty/tty_ldsem.c:340
 #1: ffff80001886b2e8 (&ldata->atomic_read_lock){+.+.}-{3:3}, at: n_tty_read+0x810/0xbe0 drivers/tty/n_tty.c:2113
3 locks held by kworker/0:1/5652:
2 locks held by kworker/u4:0/8438:
1 lock held by syz-executor.0/11597:
 #0: ffff0000105d4198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x108/0x8f0 drivers/block/nbd.c:1504
1 lock held by syz-executor.0/11605:
 #0: ffff0000105d4198 (&nbd->config_lock){+.+.}-{3:3}, at: nbd_ioctl+0x108/0x8f0 drivers/block/nbd.c:1504
3 locks held by kworker/1:0/11606:

=============================================



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