INFO: task syz-executor.5:2096 blocked for more than 140 seconds. Not tainted 4.9.194+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D24792 2096 1 0x00000004 0000000000000087 ffff8801cf308000 0000000000000000 ffff8801db621000 ffffffff83031180 ffff8801db621018 ffff8801aa4276a8 ffffffff8281af8e 0000000000000246 ffffffff831f3ca8 00ff8801cf3088a8 ffff8801db6218f0 Call Trace: [<00000000326881a2>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000ed1f0bd8>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000ef8c618e>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000ef8c618e>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<0000000004d29e8f>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<0000000089a5d359>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<00000000d897edbc>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<00000000f3861555>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000d539ca71>] do_last fs/namei.c:3541 [inline] [<00000000d539ca71>] path_openat+0xbf5/0x2f60 fs/namei.c:3665 [<0000000047094f49>] do_filp_open+0x1a1/0x280 fs/namei.c:3699 [<00000000098ba387>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<0000000096fcb9ef>] SYSC_open fs/open.c:1115 [inline] [<0000000096fcb9ef>] SyS_open+0x2d/0x40 fs/open.c:1110 [<00000000583ecbf8>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000003ffcd3d2>] 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: [<00000000ba77bdd6>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<00000000ba77bdd6>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<000000005564ff88>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 2 locks held by getty/2026: #0: (&tty->ldisc_sem){++++++}, at: [<0000000094a3a749>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+...}, at: [<000000003a235940>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/2096: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/2105: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d83d766f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.2/4582: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000117da7eb>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.2/4594: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/4600: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/4601: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/4602: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/4603: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 1 lock held by syz-executor.2/4604: #0: (loop_index_mutex){+.+.+.}, at: [<00000000a966773f>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by syz-executor.0/4584: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000015882bb5>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<0000000064b3ac78>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.4/4585: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000015882bb5>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 1 lock held by syz-executor.4/4598: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000015882bb5>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 1 lock held by syz-executor.3/4586: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000ff24b1e8>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 2 locks held by blkid/4592: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d83d766f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/4593: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d83d766f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/4596: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000fe660b82>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000d83d766f>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.194+ #0 ffff8801d98efcc8 ffffffff81b67001 0000000000000001 0000000000000000 0000000000000001 ffffffff81099d01 dffffc0000000000 ffff8801d98efd00 ffffffff81b7229c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000068664a71>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000068664a71>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<000000002fc68eff>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000622a4333>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000105eb16c>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000005aec21c6>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000005aec21c6>] check_hung_task kernel/hung_task.c:126 [inline] [<000000005aec21c6>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000005aec21c6>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000004164bf8b>] kthread+0x278/0x310 kernel/kthread.c:211 [<00000000ef1a520c>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff8282a0e1