INFO: task syz-executor.3:5322 blocked for more than 140 seconds. Not tainted 4.9.183+ #4 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D25544 5322 5321 0x00000000 0000000000000087 ffff8801d3d04740 0000000000000000 ffff8801db621000 ffffffff83031180 ffff8801db621018 ffff8801d24bf6a8 ffffffff8280a5be 0000000000000246 ffffffff831f2f48 00ff8801d3d04fe8 ffff8801db6218f0 Call Trace: [<00000000ee311797>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000006b6e8808>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000006fe04bae>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000006fe04bae>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<000000001d6da6f1>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<000000004b33109f>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000008b648d38>] do_dentry_open+0x422/0xd20 fs/open.c:772 [<00000000725c3277>] vfs_open+0x105/0x230 fs/open.c:885 [<000000008a7be85e>] do_last fs/namei.c:3457 [inline] [<000000008a7be85e>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<0000000061b1a8a2>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<000000008f58607f>] do_sys_open+0x2f0/0x610 fs/open.c:1078 [<0000000090c95a90>] SYSC_open fs/open.c:1096 [inline] [<0000000090c95a90>] SyS_open+0x2d/0x40 fs/open.c:1091 [<000000001b11e78b>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000ca166546>] 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: [<0000000058adcfca>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<0000000058adcfca>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000009458fa22>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by rs:main Q:Reg/1906: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000272db086>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #1: (sb_writers#4){.+.+.+}, at: [<000000005f8fc619>] file_start_write include/linux/fs.h:2646 [inline] #1: (sb_writers#4){.+.+.+}, at: [<000000005f8fc619>] vfs_write+0x3e9/0x520 fs/read_write.c:558 2 locks held by getty/2036: #0: (&tty->ldisc_sem){++++++}, at: [<0000000069afee7e>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<0000000052f1a47b>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.3/5322: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.5/8502: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.4/10604: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.1/12242: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/20011: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000254b9315>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ac900dc3>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.2/20021: #0: (loop_index_mutex){+.+.+.}, at: [<00000000ab3caf2e>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<0000000077e24b38>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.2/20038: #0: (loop_index_mutex){+.+.+.}, at: [<00000000ab3caf2e>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by blkid/20023: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000028c26932>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/20026: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000028c26932>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/20028: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000028c26932>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/20030: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000028c26932>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/20032: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000003ac04405>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<0000000028c26932>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.183+ #4 ffff8801d98d7cc8 ffffffff81b580a1 0000000000000000 0000000000000000 0000000000000000 ffffffff81099a01 dffffc0000000000 ffff8801d98d7d00 ffffffff81b6333c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<000000001569ed29>] __dump_stack lib/dump_stack.c:15 [inline] [<000000001569ed29>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000faa68915>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<000000003985353c>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<0000000012e02856>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<0000000085ec71bc>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<0000000085ec71bc>] check_hung_task kernel/hung_task.c:126 [inline] [<0000000085ec71bc>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<0000000085ec71bc>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000002344d4a2>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000007393ab78>] 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 skipped: idling at pc 0xffffffff82819711