INFO: task syz-executor.5:2093 blocked for more than 140 seconds. Not tainted 4.9.189+ #2 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24728 2093 1 0x00000004 0000000000000087 ffff8801cef297c0 0000000000000000 ffff8801db721000 ffff8801da6b2f80 ffff8801db721018 ffff8801a9b376a8 ffffffff82818d1e 0000000000000246 ffffffff831f3668 00ff8801cef2a068 ffff8801db7218f0 Call Trace: [<00000000ee55e76e>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<000000001f370ccf>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000827136a9>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000827136a9>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<0000000040a7421d>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<000000004e2d812c>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000000b827089>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<0000000058007fe2>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000ac72eac9>] do_last fs/namei.c:3457 [inline] [<00000000ac72eac9>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<00000000d8fd29b3>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000c01010b8>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000a234f8d7>] SYSC_open fs/open.c:1115 [inline] [<00000000a234f8d7>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000d2c00e9a>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<00000000015604d6>] 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: [<00000000b787f033>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000b787f033>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000689d0cd4>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by rs:main Q:Reg/1894: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000cb06560c>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #1: (sb_writers#4){.+.+.+}, at: [<0000000049023549>] file_start_write include/linux/fs.h:2646 [inline] #1: (sb_writers#4){.+.+.+}, at: [<0000000049023549>] vfs_write+0x3e9/0x520 fs/read_write.c:558 1 lock held by rsyslogd/1897: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000cb06560c>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2024: #0: (&tty->ldisc_sem){++++++}, at: [<000000008c0fa8a0>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000004c600da3>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2093: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/2097: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d42c3e12>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.2/2104: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d42c3e12>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.3/4612: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000009dfc505f>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000000b6b5f07>] lo_release+0x20/0x1b0 drivers/block/loop.c:1663 2 locks held by syz-executor.0/20260: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000936dfd04>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a273c552>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.4/20270: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e7d4708>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000a67af544>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.3/20271: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e7d4708>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by blkid/20275: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d42c3e12>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/20276: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d42c3e12>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 1 lock held by blkid/20281: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000438e78df>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.189+ #2 ffff8801d98d7cc8 ffffffff81b65c01 0000000000000000 0000000000000000 0000000000000000 ffffffff81099a01 dffffc0000000000 ffff8801d98d7d00 ffffffff81b70e9c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<00000000c934677d>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000c934677d>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<0000000006d899f4>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000d04607e6>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000000e02217d>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000ebf420c2>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000ebf420c2>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000ebf420c2>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000ebf420c2>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<00000000cf5220c7>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000002bea77dc>] 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 0xffffffff82827e71