INFO: task syz-executor.5:2382 blocked for more than 140 seconds. Not tainted 4.9.170+ #48 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D25256 2382 1 0x00000004 ffff8801c9578000 0000000000000000 ffff8801db721000 ffff8801a1db0000 ffff8801db721018 ffff8801a8617a28 ffffffff82801a4e 0000000041b58ab3 ffffffff82e2b9f0 00ffffff81200360 ffff8801db7218f0 1ffff100350c2f34 Call Trace: [<000000008218fd5f>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000cce76619>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000005df10684>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000005df10684>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<0000000085f0f92c>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<00000000d6be77ad>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000d6be77ad>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000974c177f>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<00000000154d8e03>] vfs_ioctl fs/ioctl.c:43 [inline] [<00000000154d8e03>] file_ioctl fs/ioctl.c:493 [inline] [<00000000154d8e03>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<0000000027b274fc>] SYSC_ioctl fs/ioctl.c:694 [inline] [<0000000027b274fc>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000480a5197>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<0000000026d690d7>] 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: [<000000001686eedc>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000001686eedc>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000000fdb535b>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1905: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000adf8a546>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2032: #0: (&tty->ldisc_sem){++++++}, at: [<000000005d632cf5>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000c635a7f3>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2382: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<0000000085f0f92c>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 3 locks held by syz-executor.1/5989: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c68d2731>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000fe92a600>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000010b50f11>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000010b50f11>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.2/5995: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<0000000085f0f92c>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe450c03>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.2/6038: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ba8604e3>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/6007: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ba8604e3>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000267a1076>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.170+ #48 ffff8801d98d7cc8 ffffffff81b4fb21 0000000000000001 0000000000000000 0000000000000001 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adbc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<000000000d6972b7>] __dump_stack lib/dump_stack.c:15 [inline] [<000000000d6972b7>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000000594e2c2>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<0000000056ce8de5>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000694512e2>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000055df1cc2>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000055df1cc2>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000055df1cc2>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000055df1cc2>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000aba969cc>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000c4bf4056>] 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 0xffffffff82810ac2