INFO: task syz-executor.5:25412 blocked for more than 140 seconds. Not tainted 4.9.189+ #1 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor.5 D25528 25412 1 0x00000004 0000000000000087 ffff8801ceeac740 0000000000000000 ffff8801db621000 ffffffff83031180 ffff8801db621018 ffff88017ce376a8 ffffffff82818c7e 0000000000000246 ffffffff831f3668 00ff8801ceeacfe8 ffff8801db6218f0 Call Trace: [<000000000ef35b63>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000402d1c33>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<000000001aaa1445>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<000000001aaa1445>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 [<000000006ac5000a>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<0000000065d405c3>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<00000000f22868d6>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<0000000071d8526f>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000f0da4a5b>] do_last fs/namei.c:3457 [inline] [<00000000f0da4a5b>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<0000000012d0367d>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<00000000bcd27354>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000b20826d4>] SYSC_open fs/open.c:1115 [inline] [<00000000b20826d4>] SyS_open+0x2d/0x40 fs/open.c:1110 [<0000000005698e1b>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<0000000078ed0c2a>] 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: [<000000001b6f4c5f>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<000000001b6f4c5f>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.?..}, at: [<00000000e1984153>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4336 3 locks held by rs:main Q:Reg/1895: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000009c52cfb8>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #1: (sb_writers#4){.+.+.+}, at: [<00000000b0b9caac>] file_start_write include/linux/fs.h:2646 [inline] #1: (sb_writers#4){.+.+.+}, at: [<00000000b0b9caac>] vfs_write+0x3e9/0x520 fs/read_write.c:558 #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<00000000e325c665>] inode_lock include/linux/fs.h:771 [inline] #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<00000000e325c665>] __generic_file_fsync+0xcd/0x1c0 fs/libfs.c:978 1 lock held by rsyslogd/1898: #0: (&f->f_pos_lock){+.+.+.}, at: [<000000009c52cfb8>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2025: #0: (&tty->ldisc_sem){++++++}, at: [<00000000f66a2b51>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:377 #1: (&ldata->atomic_read_lock){+.+...}, at: [<00000000e3d0de4b>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 1 lock held by syz-executor.5/25412: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/9620: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<0000000071a80688>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<000000004b7eb034>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 2 locks held by syz-executor.4/9651: #0: (loop_index_mutex){+.+.+.}, at: [<0000000071980da0>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000f113be3d>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1987 1 lock held by syz-executor.4/9658: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by syz-executor.4/9664: #0: (loop_index_mutex){+.+.+.}, at: [<0000000071980da0>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1973 2 locks held by blkid/9648: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ffda7989>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/9649: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ffda7989>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by blkid/9653: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ffda7989>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 2 locks held by syz-executor.2/9657: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ffda7989>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 1 lock held by syz-executor.2/9659: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 1 lock held by blkid/9655: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.1/9671: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000a7d6349b>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<00000000ffda7989>] lo_open+0x1d/0xb0 drivers/block/loop.c:1621 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 24 Comm: khungtaskd Not tainted 4.9.189+ #1 ffff8801d98efcc8 ffffffff81b65c01 0000000000000001 0000000000000000 0000000000000001 ffffffff81099a01 dffffc0000000000 ffff8801d98efd00 ffffffff81b70e9c 0000000000000001 0000000000000000 0000000000000001 Call Trace: [<00000000b1443643>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000b1443643>] dump_stack+0xc1/0x120 lib/dump_stack.c:51 [<00000000917829fc>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000c84593de>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000001f74d74b>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<000000005bb057d9>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<000000005bb057d9>] check_hung_task kernel/hung_task.c:126 [inline] [<000000005bb057d9>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<000000005bb057d9>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000001d7eb57e>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000007bfd685c>] 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 0xffffffff82827dd1