INFO: task syz-executor.5:2108 blocked for more than 140 seconds. Not tainted 4.9.168+ #40 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24872 2108 1 0x00000004 ffff8801c97497c0 ffff8801d12e5800 ffff8801db721000 ffff8801d098af80 ffff8801db721018 ffff8801a6cffa28 ffffffff8280028e 0000000041b58ab3 ffffffff82e2b728 00ffffff81200250 ffff8801db7218f0 1ffff10034d9ff34 Call Trace: [<00000000a1f710f1>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000225e7693>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000009f09a32c>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000009f09a32c>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000526426d1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 [<0000000075ebdc75>] __blkdev_driver_ioctl block/ioctl.c:294 [inline] [<0000000075ebdc75>] blkdev_ioctl+0xe14/0x19e0 block/ioctl.c:590 [<000000005d37f666>] block_ioctl+0xde/0x120 fs/block_dev.c:1696 [<000000002bb47a08>] vfs_ioctl fs/ioctl.c:43 [inline] [<000000002bb47a08>] file_ioctl fs/ioctl.c:493 [inline] [<000000002bb47a08>] do_vfs_ioctl+0xb87/0x11d0 fs/ioctl.c:677 [<00000000e6d5c488>] SYSC_ioctl fs/ioctl.c:694 [inline] [<00000000e6d5c488>] SyS_ioctl+0x8f/0xc0 fs/ioctl.c:685 [<00000000a1ef4676>] do_syscall_64+0x1ad/0x570 arch/x86/entry/common.c:285 [<000000005b4501f6>] 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: [<0000000075363638>] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [<0000000075363638>] watchdog+0x13c/0xae0 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [<000000002e963b5b>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 3 locks held by rs:main Q:Reg/1891: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000bb1202db>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #1: (sb_writers#4){.+.+.+}, at: [<00000000150a0133>] file_start_write include/linux/fs.h:2642 [inline] #1: (sb_writers#4){.+.+.+}, at: [<00000000150a0133>] vfs_write+0x3e9/0x520 fs/read_write.c:558 #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<00000000a72bfd73>] inode_lock include/linux/fs.h:768 [inline] #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<00000000a72bfd73>] __generic_file_fsync+0xcd/0x1c0 fs/libfs.c:978 1 lock held by rsyslogd/1894: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000bb1202db>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2021: #0: (&tty->ldisc_sem){++++++}, at: [<000000009aa57307>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000005f5ee019>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2108: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000526426d1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 1 lock held by syz-executor.1/2109: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004e917a15>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.4/2126: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004e917a15>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.2/6059: #0: (loop_ctl_mutex/1){+.+.+.}, at: [<00000000526426d1>] lo_ioctl+0x85/0x1a10 drivers/block/loop.c:1405 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000005d04c6a7>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 3 locks held by blkid/6063: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000355b604e>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000000b1824f5>] lo_release+0x1e/0x1b0 drivers/block/loop.c:1664 #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000010d128f8>] __lo_release drivers/block/loop.c:1642 [inline] #2: (loop_ctl_mutex#2){+.+.+.}, at: [<0000000010d128f8>] lo_release+0x84/0x1b0 drivers/block/loop.c:1665 2 locks held by blkid/6072: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004e917a15>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000211c6dc6>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by blkid/6073: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004e917a15>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000211c6dc6>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.168+ #40 ffff8801d98d7cc8 ffffffff81b4f5d1 0000000000000000 0000000000000000 0000000000000000 ffffffff81097401 dffffc0000000000 ffff8801d98d7d00 ffffffff81b5a86c 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<00000000c0a4e298>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000c0a4e298>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000f7075e15>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000282ec836>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000b1445416>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000c2cbb7cc>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000c2cbb7cc>] check_hung_task kernel/hung_task.c:125 [inline] [<00000000c2cbb7cc>] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [<00000000c2cbb7cc>] watchdog+0x661/0xae0 kernel/hung_task.c:239 [<000000000e2938d1>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ead66645>] 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 skipped: idling at pc 0xffffffff8280f302