INFO: task syz-executor.3:22905 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 22905 1 0x00000004 0000000000000083 ffff8801d2e32f80 0000000000000000 ffff8801db71ffc0 ffff8801b463df00 ffff8801db71ffd8 ffff8801cb2ef688 ffffffff8280a1de ffffffff81bbc38c ffffffff841f6b00 000060fe2460cf48 ffff8801db7208b0 Call Trace: [<00000000ea4cc68d>] schedule+0x92/0x1c0 kernel/sched/core.c:3546 [<00000000ceb2bcae>] schedule_preempt_disabled+0x13/0x20 kernel/sched/core.c:3579 [<00000000cfaff68d>] __mutex_lock_common kernel/locking/mutex.c:582 [inline] [<00000000cfaff68d>] mutex_lock_nested+0x38d/0x920 kernel/locking/mutex.c:621 [<000000003c399663>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 [<0000000079aa51ef>] __blkdev_get+0x268/0xeb0 fs/block_dev.c:1287 [<000000001255ae21>] blkdev_get+0x2e8/0x920 fs/block_dev.c:1424 [<00000000bbd5b7ed>] blkdev_open+0x1aa/0x250 fs/block_dev.c:1579 [<000000007078f57b>] do_dentry_open+0x422/0xd20 fs/open.c:791 [<000000005830c30d>] vfs_open+0x105/0x230 fs/open.c:904 [<00000000ff1d6e96>] do_last fs/namei.c:3457 [inline] [<00000000ff1d6e96>] path_openat+0xbf5/0x2f60 fs/namei.c:3581 [<00000000bb5e8811>] do_filp_open+0x1a1/0x280 fs/namei.c:3615 [<0000000072a52343>] do_sys_open+0x2f0/0x610 fs/open.c:1097 [<00000000c3390e7d>] SYSC_open fs/open.c:1115 [inline] [<00000000c3390e7d>] SyS_open+0x2d/0x40 fs/open.c:1110 [<000000006235daeb>] do_syscall_64+0x1ad/0x5c0 arch/x86/entry/common.c:288 [<000000006b23c8c3>] 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: [<0000000052220e59>] check_hung_uninterruptible_tasks kernel/hung_task.c:169 [inline] #0: (rcu_read_lock){......}, at: [<0000000052220e59>] watchdog+0x14b/0xaf0 kernel/hung_task.c:263 #1: (tasklist_lock){.+.?..}, at: [<000000005989d9ce>] debug_show_all_locks+0x7f/0x21f kernel/locking/lockdep.c:4339 3 locks held by rs:main Q:Reg/1915: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000bcec2670>] __fdget_pos+0xa8/0xd0 fs/file.c:782 #1: (sb_writers#4){.+.+.+}, at: [<00000000e45a214b>] file_start_write include/linux/fs.h:2645 [inline] #1: (sb_writers#4){.+.+.+}, at: [<00000000e45a214b>] vfs_write+0x3e9/0x520 fs/read_write.c:558 #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<000000008d07db78>] inode_lock include/linux/fs.h:771 [inline] #2: (&sb->s_type->i_mutex_key#9){++++++}, at: [<000000008d07db78>] __generic_file_fsync+0xcd/0x1c0 fs/libfs.c:982 1 lock held by rsyslogd/1918: #0: (&f->f_pos_lock){+.+.+.}, at: [<00000000bcec2670>] __fdget_pos+0xa8/0xd0 fs/file.c:782 2 locks held by getty/2045: #0: (&tty->ldisc_sem){++++++}, at: [<000000003aacb799>] ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:376 #1: (&ldata->atomic_read_lock){+.+.+.}, at: [<000000004bbe603a>] n_tty_read+0x1fe/0x1820 drivers/tty/n_tty.c:2156 2 locks held by syz-executor.3/22905: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d91317ea>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000003c399663>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 1 lock held by syz-executor.5/25577: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d91317ea>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.0/26050: #0: (&lo->lo_ctl_mutex/1){+.+.+.}, at: [<000000008d0197a7>] lo_ioctl+0x8e/0x1b10 drivers/block/loop.c:1404 #1: (&bdev->bd_mutex){+.+.+.}, at: [<00000000354a7c00>] blkdev_reread_part+0x1f/0x40 block/ioctl.c:189 1 lock held by syz-executor.0/26075: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d91317ea>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 2 locks held by syz-executor.2/26061: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e4643bc>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 #1: (&lo->lo_ctl_mutex#2){+.+.+.}, at: [<00000000a1590234>] loop_control_ioctl+0x17f/0x320 drivers/block/loop.c:1988 1 lock held by syz-executor.2/26069: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e4643bc>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.2/26070: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e4643bc>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 1 lock held by syz-executor.2/26072: #0: (loop_index_mutex){+.+.+.}, at: [<000000006e4643bc>] loop_control_ioctl+0x7a/0x320 drivers/block/loop.c:1974 2 locks held by blkid/26060: #0: (&bdev->bd_mutex){+.+.+.}, at: [<000000004140a62f>] __blkdev_put+0xbb/0x840 fs/block_dev.c:1587 #1: (loop_index_mutex){+.+.+.}, at: [<000000002db4eb57>] lo_release+0x20/0x1b0 drivers/block/loop.c:1664 2 locks held by blkid/26066: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d91317ea>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000003c399663>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 2 locks held by syz-executor.4/26084: #0: (&bdev->bd_mutex){+.+.+.}, at: [<00000000d91317ea>] __blkdev_get+0x10e/0xeb0 fs/block_dev.c:1273 #1: (loop_index_mutex){+.+.+.}, at: [<000000003c399663>] lo_open+0x1d/0xb0 drivers/block/loop.c:1622 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 24 Comm: khungtaskd Not tainted 4.9.202+ #0 ffff8801d98d7cc8 ffffffff81b55d2b 0000000000000000 0000000000000000 0000000000000000 ffffffff8109a001 dffffc0000000000 ffff8801d98d7d00 ffffffff81b60fcc 0000000000000000 0000000000000000 0000000000000000 Call Trace: [<00000000e49a78db>] __dump_stack lib/dump_stack.c:15 [inline] [<00000000e49a78db>] dump_stack+0xcb/0x130 lib/dump_stack.c:56 [<000000001593005d>] nmi_cpu_backtrace.cold+0x47/0x87 lib/nmi_backtrace.c:99 [<00000000e3cb0e12>] nmi_trigger_cpumask_backtrace+0x124/0x155 lib/nmi_backtrace.c:60 [<000000005f3123f3>] arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:37 [<00000000f55851cd>] trigger_all_cpu_backtrace include/linux/nmi.h:58 [inline] [<00000000f55851cd>] check_hung_task kernel/hung_task.c:126 [inline] [<00000000f55851cd>] check_hung_uninterruptible_tasks kernel/hung_task.c:183 [inline] [<00000000f55851cd>] watchdog+0x670/0xaf0 kernel/hung_task.c:263 [<000000003ef575d7>] kthread+0x278/0x310 kernel/kthread.c:211 [<000000008f4c20d4>] ret_from_fork+0x5c/0x70 arch/x86/entry/entry_64.S:375 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at pc 0xffffffff82819331