INFO: task syz-executor.3:12379 blocked for more than 140 seconds. Not tainted 4.9.202+ #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.3 D25544 12379 1 0x00000004 0000000000000083 ffff8801a12297c0 ffff8801d62aee00 ffff8801db61ffc0 ffff8801cf08af80 ffff8801db61ffd8 ffff8801c8d47688 ffffffff8280a1de 0000000041b58ab3 ffffffff82e2ad88 00ffffff812051e0 ffff8801db6208b0 Call Trace: [<0000000022961b1d>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000da51441e>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<0000000027d5b959>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<0000000027d5b959>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000407579f5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 [<00000000cb1e7650>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<00000000de162e6b>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<000000008db920bb>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<00000000bb6b6779>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<00000000c2a72041>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000c5450dba>] do_last fs/namei.c:3457 [inline] [<00000000c5450dba>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<00000000411f9fa5>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000c7b7ca0d>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000f07b6b62>] SYSC_open fs/open.c:1115 [inline] [<00000000f07b6b62>] SyS_open+0x2d/0x40 fs/open.c:1110 [<0000000011d39137>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<0000000021211d64>] 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: [<000000009c8ab129>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000009c8ab129>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.+..}, at: [<00000000d61eec77>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 1 lock held by rsyslogd/1896: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000f8e04c2a>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2024: #0: (&tty->ldisc_sem){++++++}, at: [<000000009434487f>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<000000006db80454>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/12379: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000407579f5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.4/17323: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000edd956f3>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<00000000481966f6>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664 1 lock held by syz-executor.4/17326: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000000f92c5c1>] blkdev_put+0x2b/0x560 fs/block_dev.c:1629 2 locks held by syz-executor.2/17338: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000407579f5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.2/17372: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/17344: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<00000000bf0559f4>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000009f3ab647>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/17352: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/17368: #0: (loop_index_mutex){+.+.+.}, at: [<000000004c497623>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000436fa485>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 2 locks held by blkid/17369: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000407579f5>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by blkid/17370: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000e71989c4>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.202+ #0 ffff8801d98d7cc8 ffffffff81b55d2b 0000000000000001 0000000000000000 0000000000000001 ffffffff8109a001 dffffc0000000000 ffff8801d98d7d00 ffffffff81b60fcc 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<0000000043cc10db>] __dump_stack lib/dump_stack.c:15 [inline] [<0000000043cc10db>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<00000000ad7d7bb5>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000f12449a4>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<00000000f5bdc8bb>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000afc13d41>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000afc13d41>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000afc13d41>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000afc13d41>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<0000000060da3bb4>] kthread+0x278/0x310 kernel/kthread.c:211 [<0000000096f0ddc6>] 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 0xffffffff82819331