INFO: task syz-executor.0:2093 blocked for more than 140 seconds. Not tainted 4.9.141+ #23 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.0 D24456 2093 1 0x20020004 ffff8801d03217c0 ffff8801d004f380 ffff8801ca732680 ffff8801d105df00 ffff8801db621018 ffff8801af5b7658 ffffffff828075c2 0000000000000000 ffff8801d0322070 ffffed003a06440d 00ff8801d03217c0 ffff8801db6218f0 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3553 [] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3586 [] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [] mutex_lock_nested+0x38d/0x900 kernel/locking/mutex.c:621 [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 [] blkdev_get+0x2da/0x920 fs/block_dev.c:1416 [] blkdev_open+0x1a5/0x250 fs/block_dev.c:1571 [] do_dentry_open+0x3ef/0xc90 fs/open.c:766 [] vfs_open+0x11c/0x210 fs/open.c:879 [] do_last fs/namei.c:3410 [inline] [] path_openat+0x542/0x2790 fs/namei.c:3534 [] do_filp_open+0x197/0x270 fs/namei.c:3568 [] do_sys_open+0x30d/0x5c0 fs/open.c:1072 [] C_SYSC_open fs/compat.c:1081 [inline] [] compat_SyS_open+0x2a/0x40 fs/compat.c:1079 [] do_syscall_32_irqs_on arch/x86/entry/common.c:328 [inline] [] do_fast_syscall_32+0x2f1/0xa10 arch/x86/entry/common.c:390 [] entry_SYSENTER_compat+0x90/0xa2 arch/x86/entry/entry_64_compat.S:137 Showing all locks held in the system: 2 locks held by khungtaskd/24: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x11c/0xa20 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x79/0x218 kernel/locking/lockdep.c:4336 1 lock held by rsyslogd/1897: #0: (&f->f_pos_lock){+.+.+.}, at: [] __fdget_pos+0xac/0xd0 fs/file.c:781 2 locks held by getty/2024: #0: (&tty->ldisc_sem){++++++}, at: [] ldsem_down_read+0x32/0x40 drivers/tty/tty_ldsem.c:367 #1: (&ldata->atomic_read_lock){+.+...}, at: [] n_tty_read+0x202/0x16e0 drivers/tty/n_tty.c:2142 1 lock held by syz-executor.0/2093: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 2 locks held by syz-executor.4/5346: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 #1: (loop_index_mutex){+.+.+.}, at: [] lo_open+0x1b/0xa0 drivers/block/loop.c:1589 2 locks held by syz-executor.1/6175: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 #1: (loop_index_mutex){+.+.+.}, at: [] lo_open+0x1b/0xa0 drivers/block/loop.c:1589 1 lock held by syz-executor.5/6989: #0: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_put+0x2a/0x560 fs/block_dev.c:1621 1 lock held by syz-executor.5/7010: #0: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_put+0x2a/0x560 fs/block_dev.c:1621 2 locks held by syz-executor.2/8202: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_put+0xbb/0x840 fs/block_dev.c:1579 #1: (loop_index_mutex){+.+.+.}, at: [] lo_release+0x1f/0x1a0 drivers/block/loop.c:1631 1 lock held by syz-executor.5/8895: #0: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_put+0x2a/0x560 fs/block_dev.c:1621 1 lock held by syz-executor.5/15303: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 2 locks held by syz-executor.5/15311: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [] loop_control_ioctl+0x186/0x300 drivers/block/loop.c:1955 1 lock held by syz-executor.5/15313: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 1 lock held by syz-executor.5/15314: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 1 lock held by syz-executor.5/15320: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 1 lock held by syz-executor.5/15322: #0: (loop_index_mutex){+.+.+.}, at: [] loop_control_ioctl+0x7a/0x300 drivers/block/loop.c:1941 2 locks held by syz-executor.3/15304: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_put+0xbb/0x840 fs/block_dev.c:1579 #1: (loop_index_mutex){+.+.+.}, at: [] lo_release+0x1f/0x1a0 drivers/block/loop.c:1631 2 locks held by syz-executor.2/15310: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [] lo_ioctl+0x8c/0x1910 drivers/block/loop.c:1372 #1: (&bdev->bd_mutex){+.+.+.}, at: [] blkdev_reread_part+0x1e/0x40 block/ioctl.c:189 1 lock held by blkid/15329: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 1 lock held by blkid/15330: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 1 lock held by blkid/15332: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd60 fs/block_dev.c:1268 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.141+ #23 ffff8801d9907d08 ffffffff81b42e79 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810983b0 ffff8801d9907d40 ffffffff81b4df89 0000000000000001 0000000000000000 0000000000000003 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace.cold.0+0x48/0x87 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x12c/0x151 lib/nmi_backtrace.c:60 [] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [] check_hung_task kernel/hung_task.c:125 [inline] [] check_hung_uninterruptible_tasks kernel/hung_task.c:182 [inline] [] watchdog+0x6ad/0xa20 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:373 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff82816496