INFO: task syz-executor.5:2118 blocked for more than 140 seconds. Not tainted 4.9.169+ #41 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24792 2118 1 0x00000004 ffff8801d659c740 0000000000000000 ffff8801db721000 ffff8801da6b2f80 ffff8801db721018 ffff8801ae217988 ffffffff8280152e 0000000000000000 ffffffff830c1d40 00ff8801ae2179b0 ffff8801db7218f0 1ffff10035c42f20 Call Trace: [<00000000d9406f46>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000f6ac6e04>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000059b3fdef>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000059b3fdef>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000248027f5>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 [<0000000035dd2190>] loop_reread_partitions+0x7c/0x90 drivers/block/loop.c:638 [<0000000001303c5f>] loop_clr_fd+0x7dd/0xa60 drivers/block/loop.c:1082 [<000000008c66a331>] lo_ioctl+0x7b6/0x1a10 drivers/block/loop.c:1415 [<00000000a8bf78a0>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<00000000a8bf78a0>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<00000000cb1d9fbe>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000000e9bb370>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000000e9bb370>] file_ioctl fs/ioctl.c:493 [inline] [<000000000e9bb370>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000baa7af57>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000baa7af57>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<000000003a535308>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<00000000e17f09d5>] 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: [<000000004e7c8931>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<000000004e7c8931>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<00000000af5b2cf8>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1903: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000e73413ed>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2031: #0: (&tty->ldisc_sem){++++++}, at: [<0000000033839954>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000082cfc00>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.5/2118: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<000000003ee48921>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000248027f5>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.2/2123: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f0f261b9>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000088112645>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.0/2126: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f0f261b9>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000088112645>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 3 locks held by syz-executor.3/14175: #0: (&bdev->bd_mutex){+.+.+.}, at: [<0000000030c194a7>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000bd793244>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000f5d280c3>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000f5d280c3>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 1 lock held by blkid/14186: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f0f261b9>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/14187: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000f0f261b9>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000088112645>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.169+ #41 ffff8801d98d7cc8 ffffffff81b4f7f1 0000000000000000 0000000000000000 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5aa8c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<00000000b241ec43>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000b241ec43>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000e08861a2>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000b950fd5d>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000400e2479>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000084d4cbff>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000084d4cbff>] check_hung_task kernel/hung_task.c:125 [inline] [<0000000084d4cbff>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<0000000084d4cbff>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<000000008606a3ab>] kthread+0x278/0x310 kernel/kthread.c:211 [<0000000068a281f5>] 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 CPU: 1 PID: 1901 Comm: rs:main Q:Reg Not tainted 4.9.169+ #41 task: 00000000385b16f8 task.stack: 000000001c5bdc57 RIP: 0010:[] c [<00000000fa98864a>] SyS_write+0x0/0x1c0 fs/read_write.c:598 RSP: 0018:ffff8801d5d07ef8 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: ffffffff81514c70 RCX: 0000000000000000 RDX: 0000000000000053 RSI: 0000000001e24a90 RDI: 0000000000000005 RBP: ffff8801d5d07f48 R08: 0000000001e24ad3 R09: 0000000000000000 R10: 1ffff1003aba0ff9 R11: 0000000000000000 R12: ffff8801d5d07f58 R13: ffff8801d5d07fd0 R14: ffff8801d3c5c740 R15: 0000000000000000 FS: 00007f12d50d3700(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00000000024903e0 CR3: 00000001d4bcb000 CR4: 00000000001606b0 Stack: ffffffff810056bdc 0000000000000000c 1ffff1003aba0ff9c 0000000000000000c 0000000000000000c 0000000000000000c 0000000000000000c 0000000000000000c 0000000000000000c 0000000000000000c 0000000000000000c ffffffff82811993c Call Trace: [<00000000e17f09d5>] entry_SYSCALL_64_after_swapgs+0x5d/0xdb Code: c48 c8b cbd c60 cff cff cff ce8 cef c40 cfe cff ce9 c10 cff cff cff ce8 cd5 c58 cbc cff c48 c8b cbd c60 cff cff cff ce8 c79 c41 cfe cff ce9 c50 cff cff cff c0f c1f c40 c00 c<55> c48 c89 ce5 c41 c57 c49 cbf c00 c00 c00 c00 c00 cfc cff cdf c41 c56 c41 c55 c4c c