INFO: task syz-executor.0:2125 blocked for more than 140 seconds. Not tainted 4.9.169+ #44 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D25528 2125 1 0x00000004 ffff8801d1718000 ffff8801d062f900 ffff8801db721000 ffff8801d9925f00 ffff8801db721018 ffff8801aa24fa28 ffffffff8280152e ffffffff82e2ba28 ffffffff81208040 0000000200000000 ffff8801db7218f0 1ffff10035449f34 Call Trace: [<000000006f5b5b61>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<0000000031ca23d7>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000004114307e>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000004114307e>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000a251730b>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<0000000070caf85c>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<0000000070caf85c>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000d4e17cc0>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000009c609e49>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000009c609e49>] file_ioctl fs/ioctl.c:493 [inline] [<000000009c609e49>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<000000009706389b>] SYSC_ioctl fs/ioctl.c:694 [inline] [<000000009706389b>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<0000000017d1c754>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<0000000075fd7961>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [<000000000ebfa5db>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<000000000ebfa5db>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<000000005f4f7f0c>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1911: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000008b6c5380>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2038: #0: (&tty->ldisc_sem){++++++}, at: [<00000000e200abc0>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000b424b64d>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.0/2125: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a251730b>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.1/2127: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 3 locks held by syz-executor.4/2132: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000374b3a26>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000199cf232>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000096d1fb7c>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000096d1fb7c>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.2/2133: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b6a77c84>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.3/17373: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000a251730b>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d42953ce>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.3/17392: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/17379: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b6a77c84>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by blkid/17389: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000b6a77c84>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/17391: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000033505afd>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.169+ #44 ffff8801d98d7cc8 ffffffff81b4f7f1 0000000000000000 0000000000000000 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5aa8c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<0000000091624035>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000091624035>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<0000000032293aa7>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000b840b738>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000697475f7>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000018e7cab5>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000018e7cab5>] check_hung_task kernel/hung_task.c:125 [inline] [<0000000018e7cab5>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<0000000018e7cab5>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<000000002d3b8f1f>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ec957994>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff828105a2