INFO: task syz-executor2:10762 blocked for more than 120 seconds. Not tainted 4.9.66-g87cdf4e #104 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor2 D28864 10762 3530 0x00000004 ffff8801b8d18000 0000000000000000 ffff8801cae9e4c0 ffffffff84426880 ffff8801db221418 ffff8801b71b7b10 ffffffff838981cb ffffffff81239470 ffff8801b71b7bb8 00ffffff81cfbb2a ffff8801db221ce8 ffff8801db221d10 Call Trace: [] schedule+0x7f/0x1b0 kernel/sched/core.c:3550 [] schedule_timeout+0x643/0x1220 kernel/time/timer.c:1770 [] io_schedule_timeout+0x1be/0x390 kernel/sched/core.c:5172 [] do_wait_for_common kernel/sched/completion.c:75 [inline] [] __wait_for_common kernel/sched/completion.c:93 [inline] [] wait_for_common_io kernel/sched/completion.c:107 [inline] [] wait_for_completion_io+0x20e/0x2e0 kernel/sched/completion.c:155 [] submit_bio_wait+0x11b/0x180 block/bio.c:885 [] blkdev_issue_flush+0x157/0x220 block/blk-flush.c:518 [] blkdev_fsync+0x85/0xb0 fs/block_dev.c:378 [] vfs_fsync_range+0x10a/0x250 fs/sync.c:195 [] vfs_fsync fs/sync.c:209 [inline] [] do_fsync+0x42/0xb0 fs/sync.c:219 [] SYSC_fsync fs/sync.c:228 [inline] [] SyS_fsync+0x16/0x20 fs/sync.c:226 [] 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/3228: #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 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 514 Comm: khungtaskd Not tainted 4.9.66-g87cdf4e #104 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 ffff8801d8e6fd00 ffffffff81d90749 0000000000000000 0000000000000001 0000000000000001 0000000000000001 ffffffff810ba170 ffff8801d8e6fd38 ffffffff81d9b86d 0000000000000001 0000000000000000 ffff8801ca308418 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:437 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 skipped: idling at pc 0xffffffff838a8606