INFO: task syz-executor.4:2101 blocked for more than 140 seconds. Not tainted 4.9.202+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.4 D25016 2101 1 0x00000004 0000000000000083 ffff8801d7f34740 ffff8801d0a9cd00 ffff8801db61ffc0 ffff8801d1a297c0 ffff8801db61ffd8 ffff8801a56af688 ffffffff8280a1de ffff8801d7f34740 ffffffff841f6b00 00ff8801a56af5e8 ffff8801db6208b0 Call Trace: [<00000000035afb2f>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000000616af25>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000c3c458d8>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000c3c458d8>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000008078432b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 [<0000000033b837ad>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<000000005247b815>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<00000000a0cc6c01>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000004ec10d14>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<00000000a4507b4d>] vfs_open+0x105/0x230 fs/open.c:904 [<000000001c8e4c91>] do_last fs/namei.c:3457 [inline] [<000000001c8e4c91>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<00000000e58c0101>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<0000000086c2ea5a>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000d2cb2811>] SYSC_open fs/open.c:1115 [inline] [<00000000d2cb2811>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000239e692b>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000009e1fb102>] 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: [<00000000ca07637a>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000ca07637a>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000005905ee5a>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 2 locks held by getty/2028: #0: (&tty->ldisc_sem){++++++}, at: [<0000000040f80e99>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<00000000b6460626>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.4/2101: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000008078432b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.2/4402: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a290bcb1>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 2 locks held by blkid/4405: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c17cb657>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000003aea3914>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664 2 locks held by syz-executor.3/4415: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000c17cb657>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000003aea3914>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664 1 lock held by syz-executor.3/4448: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.3/4450: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.5/4420: #0: (loop_index_mutex){+.+.+.}, at: [<00000000b769a494>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000528ec996>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 2 locks held by syz-executor.0/4430: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000c1613359>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000001642e856>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/4433: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000008078432b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.1/4442: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000008078432b>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/4441: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by blkid/4445: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000006e2915de>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.202+ #0 ffff8801d98f7cc8 ffffffff81b55d2b 0000000000000000 0000000000000000 0000000000000000 ffffffff8109a001 dffffc0000000000 ffff8801d98f7d00 ffffffff81b60fcc 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000005c3b4047>] __dump_stack lib/dump_stack.c:15 [inline] [<000000005c3b4047>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<000000001e72f6da>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000c7fef1b0>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000b978ee2a>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000319fa209>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000319fa209>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000319fa209>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000319fa209>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<0000000071c4d8ba>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ed204bdd>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.9.202+ #0 task: 000000001ff94229 task.stack: 0000000037f00f1d RIP: 0010:[] c [<000000005c2f7a89>] __lock_acquire+0x8b3/0x4390 kernel/locking/lockdep.c:3371 RSP: 0018:ffff8801db707d30 EFLAGS: 00000097 RAX: 0000000000000001 RBX: ffffffff83623460 RCX: 1ffff1003b4d670a RDX: 1ffff1003b4d6705 RSI: ffff8801da6b3830 RDI: ffffffff83623478 RBP: ffff8801db707eb8 R08: 0000000000000001 R09: 00000000000049f1 R10: ffff8801da6b3830 R11: 0000000000000001 R12: dffffc0000000000 R13: ffff8801da6b3830 R14: f6345063bd17a015 R15: ffff8801da6b2f80 FS: 0000000000000000(0000) GS:ffff8801db700000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f08eaf1c05d CR3: 00000001d0121000 CR4: 00000000001606b0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000600 Stack: ffff8801db707d30c ffff8801db707d78c ffffffff81bbc38cc ffff8801da6b3828c ffff8801da6b3830c 0000000000000246c ffffffff811d70e3c 0000000000000001c 0000000100000000c ffff8801da6b2f80c 0000000000000001c ffffffff83c77590c Call Trace: [<00000000e7581a3d>] lock_acquire+0x133/0x3d0 kernel/locking/lockdep.c:3759 [<000000006d7d5f65>] seqcount_lockdep_reader_access include/linux/seqlock.h:80 [inline] [<000000006d7d5f65>] read_seqcount_begin include/linux/seqlock.h:163 [inline] [<000000006d7d5f65>] ktime_get kernel/time/timekeeping.c:760 [inline] [<000000006d7d5f65>] ktime_get+0x6f/0x1c0 kernel/time/timekeeping.c:750 [<000000007e61f238>] tick_nohz_irq_enter kernel/time/tick-sched.c:1144 [inline] [<000000007e61f238>] tick_irq_enter+0xcc/0x220 kernel/time/tick-sched.c:1165 [<00000000566dd949>] irq_enter+0xb3/0xd0 kernel/softirq.c:349 [<000000002b1552ba>] smp_reschedule_interrupt+0xa/0x90 arch/x86/kernel/smp.c:275 [<00000000f1aa78cc>] reschedule_interrupt+0xa5/0xb0 arch/x86/entry/entry_64.S:676 d [<00000000eb42935d>] ? native_safe_halt+0x41/0x60 arch/x86/include/asm/irqflags.h:59 [<0000000001ecf9f6>] arch_safe_halt arch/x86/include/asm/paravirt.h:104 [inline] [<0000000001ecf9f6>] default_idle+0x56/0x370 arch/x86/kernel/process.c:500 [<00000000f85acc10>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:491 [<00000000016a89f2>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97 [<00000000f558166c>] cpuidle_idle_call kernel/sched/idle.c:155 [inline] [<00000000f558166c>] cpu_idle_loop kernel/sched/idle.c:248 [inline] [<00000000f558166c>] cpu_startup_entry+0x283/0x3a0 kernel/sched/idle.c:303 [<0000000002702d3c>] start_secondary+0x31c/0x410 arch/x86/kernel/smpboot.c:251 Code: cc0 c74 c08 c3c c03 c0f c8e c2b c2d c00 c00 c41 c8b c87 ca8 c08 c00 c00 c83 cc0 c01 c83 cf8 c2f c41 c89 c87 ca8 c08 c00 c00 c0f c87 cb9 c17 c00 c00 c3b c05 cbd cce c61 c02 c<41> cbb c01 c00 c00 c00 c0f c86 c99 c00 c00 c00 c89 c05 cab cce c61 c02 ce9 c8e c00 c