INFO: task syz-executor.5:2124 blocked for more than 140 seconds. Not tainted 4.9.171+ #49 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D25464 2124 1 0x00000004 ffff8801cfecc740 ffff8801d0b49600 ffff8801db721000 ffff8801cfc7af80 ffff8801db721018 ffff8801b1adfb28 ffffffff82801dde ffff8801cfecc740 ffff8801b1adfc00 0000000000000046 ffff8801db7218f0 1ffff1003635bf54 Call Trace: [<000000006debe064>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000acaada73>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000005c2044fd>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000005c2044fd>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000c7b3c216>] __lo_release drivers/block/loop.c:1642 [inline] [<00000000c7b3c216>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 [<00000000b96fced4>] __blkdev_put+0x461/0x840 fs/block_dev.c:1606 [<0000000086250784>] blkdev_put+0x88/0x560 fs/block_dev.c:1671 [<00000000cf8e18c6>] blkdev_close+0x8b/0xb0 fs/block_dev.c:1678 [<000000005c272562>] __fput+0x274/0x720 fs/file_table.c:208 [<00000000fd3475aa>] ____fput+0x16/0x20 fs/file_table.c:244 [<000000000d0216d9>] task_work_run+0x108/0x180 kernel/task_work.c:116 [<00000000f0092703>] tracehook_notify_resume include/linux/tracehook.h:191 [inline] [<00000000f0092703>] exit_to_usermode_loop+0x13b/0x160 arch/x86/entry/common.c:162 [<00000000e0b44480>] prepare_exit_to_usermode arch/x86/entry/common.c:194 [inline] [<00000000e0b44480>] syscall_return_slowpath arch/x86/entry/common.c:263 [inline] [<00000000e0b44480>] do_syscall_64+0x3f7/0x570 arch/x86/entry/common.c:290 [<00000000a443eaee>] 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: [<000000007e06d2a8>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000007e06d2a8>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000c052e38a>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2044: #0: (&tty->ldisc_sem){++++++}, at: [<00000000d547fdd6>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000423cd253>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 3 locks held by syz-executor.5/2124: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003c5d7618>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ce89c0ec>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c7b3c216>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<00000000c7b3c216>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by syz-executor.4/2128: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e2168fcd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.0/2135: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e2168fcd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.2/2136: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/2141: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e2168fcd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.2/3412: #0: (&tty->ldisc_sem){++++++}, at: [<00000000d547fdd6>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000423cd253>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/4067: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000f61452f2>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000002022ed4c>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by blkid/4070: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e2168fcd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/4072: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by blkid/4073: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e340ec59>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000e2168fcd>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.171+ #49 ffff8801d98d7cc8 ffffffff81b4fb61 0000000000000001 0000000000000000 0000000000000001 ffffffff81097501 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5adfc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000c5e21c07>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000c5e21c07>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<0000000050ae9771>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000bc684360>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000471ad8c6>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000007ccf63a5>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000007ccf63a5>] check_hung_task kernel/hung_task.c:126 [inline] [<000000007ccf63a5>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000007ccf63a5>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000007198b9f1>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000fe200961>] 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 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.9.171+ #49 task: 000000009c479bf5 task.stack: 000000006422e7e8 RIP: 0010:[] c [<00000000be457723>] reschedule_interrupt+0x0/0xb0 arch/x86/entry/entry_64.S:671 RSP: 0018:ffffffff83007d98 EFLAGS: 00000046 RAX: 0000000000000007 RBX: ffffffff833e37c8 RCX: 0000000000000000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffffffff83031a2c RBP: ffffffff83007df0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000 R13: ffffffff83031180 R14: dffffc0000000000 R15: ffffffff83031180 FS: 0000000000000000(0000) GS:ffff8801db600000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000000001803000 CR3: 00000001d4cea000 CR4: 00000000001606b0 Stack: ffffffff82810e52c 0000000000000010c 0000000000000246c ffffffff83007dc0c 0000000000000018c ffffffff828103e6c ffffffff83031180c 0000000000000000c ffffffff83031180c dffffc0000000000c ffffffff83031180c ffffffff83007e00c Call Trace: [<0000000019f672a1>] arch_cpu_idle+0x10/0x20 arch/x86/kernel/process.c:428 [<00000000855b9295>] default_idle_call+0x36/0x60 kernel/sched/idle.c:97 [<0000000051929695>] cpuidle_idle_call kernel/sched/idle.c:155 [inline] [<0000000051929695>] cpu_idle_loop kernel/sched/idle.c:248 [inline] [<0000000051929695>] cpu_startup_entry+0x283/0x3a0 kernel/sched/idle.c:303 [<00000000bc17dc8e>] rest_init+0x18b/0x194 init/main.c:409 [<000000004486c7c6>] start_kernel+0x61e/0x652 init/main.c:671 [<00000000a3e40641>] x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:196 [<0000000069119fb2>] x86_64_start_kernel+0x137/0x15a arch/x86/kernel/head64.c:177 Code: c7d c01 c00 c65 c48 c0f c44 c24 c25 c98 c7d c01 c00 c57 ce8 c24 ce3 c7e cfe ce8 c13 c18 c00 c00 ce9 c9b cec cff cff c0f c1f c40 c00 c66 c2e c0f c1f c84 c00 c00 c00 c00 c00 c<68> c02 cff cff cff cfc c48 c83 cc4 c88 c4c c89 c5c c24 c30 c4c c89 c54 c24 c38 c4c c