INFO: task syz-executor.1:2118 blocked for more than 140 seconds. Not tainted 4.9.168+ #40 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.1 D25528 2118 1 0x00000004 ffff8801ce7497c0 0000000000000000 ffff8801db621000 ffff8801a5255f00 ffff8801db621018 ffff8801aaa1fa28 ffffffff8280028e 0000000041b58ab3 ffffffff82e2b728 00ffffff81200250 ffff8801db6218f0 1ffff10035543f34 Call Trace: [<00000000f5047822>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000007f9c160f>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000da62db47>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000da62db47>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000db904dd1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<000000006e541c28>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<000000006e541c28>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<000000001fad0c84>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000005051becf>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000005051becf>] file_ioctl fs/ioctl.c:493 [inline] [<000000005051becf>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000df8041d9>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000df8041d9>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<000000005d2f376f>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<00000000d6593588>] 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: [<000000002d472f1f>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<000000002d472f1f>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<000000004759cf45>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1903: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000002e65078c>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2031: #0: (&tty->ldisc_sem){++++++}, at: [<00000000d4ead64d>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000003cc5406b>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.1/2118: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000db904dd1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.3/2132: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000db904dd1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 2 locks held by syz-executor.4/24471: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000005acc7f9b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<0000000036341bb5>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 2 locks held by syz-executor.0/18555: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f94cbc36>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e354ee2f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.2/23537: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000001aebf687>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 3 locks held by syz-executor.4/13293: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000005acc7f9b>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<0000000036341bb5>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000003ead71eb>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<000000003ead71eb>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.2/13304: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000db904dd1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000493594dc>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by blkid/13322: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f94cbc36>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/13323: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f94cbc36>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e354ee2f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/13359: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f94cbc36>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.168+ #40 ffff8801d98d7cc8 ffffffff81b4f5d1 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5a86c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000f1e1bbf7>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000f1e1bbf7>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000003ef09014>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000963e9914>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000fbc9a4fc>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000047002248>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000047002248>] check_hung_task kernel/hung_task.c:125 [inline] [<0000000047002248>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<0000000047002248>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<000000001eb8b138>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ac0fafc5>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff8280f302