INFO: task syz-executor3:13952 blocked for more than 120 seconds. Not tainted 4.9.64-gfbb7468 #94 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor3 D28736 13952 3506 0x00000004 ffff8801c6150000 ffff8801cb8a24c0 ffff8801ca2def40 ffff8801ce090000 ffff8801db321418 ffff8801ce3279b0 ffffffff83897fdb ffffffff812395a0 ffffe8ffffd03d00 00ff8801ce327a70 ffff8801db321d40 ffff8801db321d68 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3540 [] schedule_timeout+0x643/0x1220 kernel/time/timer.c:1770 [] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5162 [] io_schedule include/linux/sched.h:460 [inline] [] bit_wait_io+0x19/0xa0 kernel/sched/wait.c:582 [] __wait_on_bit+0x57/0x120 kernel/sched/wait.c:383 [] wait_on_page_bit+0xf4/0x140 mm/filemap.c:802 [] wait_on_page_writeback include/linux/pagemap.h:526 [inline] [] __filemap_fdatawait_range+0x1c1/0x2b0 mm/filemap.c:453 [] filemap_fdatawait_keep_errors+0x63/0x80 mm/filemap.c:511 [] fdatawait_one_bdev+0x50/0x70 fs/sync.c:94 [] iterate_bdevs+0x109/0x260 fs/block_dev.c:1978 [] sys_sync+0xe1/0x170 fs/sync.c:116 [] entry_SYSCALL_64_fastpath+0x23/0xc6 Showing all locks held in the system: 2 locks held by khungtaskd/514: #0: (rcu_read_lock){......}, at: [] check_hung_uninterruptible_tasks kernel/hung_task.c:168 [inline] #0: (rcu_read_lock){......}, at: [] watchdog+0x125/0xa70 kernel/hung_task.c:239 #1: (tasklist_lock){.+.+..}, at: [] debug_show_all_locks+0x70/0x280 kernel/locking/lockdep.c:4336 2 locks held by getty/3217: #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+0x1f4/0x16c0 drivers/tty/n_tty.c:2133 3 locks held by kworker/u4:5/3814: #0: ("writeback"){++++.+}, at: [] __write_once_size include/linux/compiler.h:272 [inline] #0: ("writeback"){++++.+}, at: [] atomic64_set arch/x86/include/asm/atomic64_64.h:33 [inline] #0: ("writeback"){++++.+}, at: [] atomic_long_set include/asm-generic/atomic-long.h:56 [inline] #0: ("writeback"){++++.+}, at: [] set_work_data kernel/workqueue.c:616 [inline] #0: ("writeback"){++++.+}, at: [] set_work_pool_and_clear_pending kernel/workqueue.c:643 [inline] #0: ("writeback"){++++.+}, at: [] process_one_work+0x6a9/0x15f0 kernel/workqueue.c:2083 #1: ((&(&wb->dwork)->work)){+.+.+.}, at: [] process_one_work+0x6db/0x15f0 kernel/workqueue.c:2087 #2: (&type->s_umount_key#28){.+.+..}, at: [] trylock_super+0x20/0x100 fs/super.c:393 1 lock held by syz-executor3/13952: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor3/13959: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor6/13985: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor6/14007: #0: (&bdev->bd_mutex){+.+.+.}, at: [] iterate_bdevs+0xc8/0x260 fs/block_dev.c:1976 1 lock held by syz-executor2/14002: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor2/14011: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor2/14016: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor2/14023: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor7/14006: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor7/14018: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor5/14042: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 1 lock held by syz-executor5/14053: #0: (&bdev->bd_mutex){+.+.+.}, at: [] __blkdev_get+0x10c/0xd50 fs/block_dev.c:1268 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.64-gfbb7468 #94 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d8f8fd00 ffffffff81d90429 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810ba170 ffff8801d8f8fd38 ffffffff81d9b54d 0000000000000001 0000000000000000 ffff8801d1300418 Call Trace: [] __dump_stack lib/dump_stack.c:15 [inline] [] dump_stack+0xc1/0x128 lib/dump_stack.c:51 [] nmi_cpu_backtrace+0xfd/0x120 lib/nmi_backtrace.c:99 [] nmi_trigger_cpumask_backtrace+0x117/0x190 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+0x6f0/0xa70 kernel/hung_task.c:239 [] kthread+0x26d/0x300 kernel/kthread.c:211 [] ret_from_fork+0x2a/0x40 arch/x86/entry/entry_64.S:433 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff838a8416