INFO: task syz-executor139:9745 blocked for more than 143 seconds. Not tainted 5.5.0-rc2-next-20191220-syzkaller #0 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-executor139 D26816 9745 9743 0x00004000 Call Trace: context_switch kernel/sched/core.c:3385 [inline] __schedule+0x934/0x1f90 kernel/sched/core.c:4081 schedule+0xdc/0x2b0 kernel/sched/core.c:4155 io_schedule+0x1c/0x70 kernel/sched/core.c:5799 wait_on_page_bit_common mm/filemap.c:1175 [inline] wait_on_page_bit+0x27c/0xa60 mm/filemap.c:1224 wait_on_page_writeback+0x1b2/0x4f0 mm/page-writeback.c:2822 __filemap_fdatawait_range+0x145/0x340 mm/filemap.c:526 filemap_fdatawait_keep_errors+0x22/0x30 mm/filemap.c:621 wait_sb_inodes fs/fs-writeback.c:2436 [inline] sync_inodes_sb+0x6e4/0xb50 fs/fs-writeback.c:2558 __sync_filesystem fs/sync.c:34 [inline] sync_filesystem fs/sync.c:67 [inline] sync_filesystem+0x168/0x260 fs/sync.c:48 generic_shutdown_super+0x75/0x370 fs/super.c:448 kill_block_super+0xa0/0x100 fs/super.c:1444 deactivate_locked_super+0x95/0x100 fs/super.c:335 deactivate_super fs/super.c:366 [inline] deactivate_super+0x1bd/0x1e0 fs/super.c:362 cleanup_mnt+0x351/0x4c0 fs/namespace.c:1102 __cleanup_mnt+0x16/0x20 fs/namespace.c:1109 task_work_run+0x145/0x1c0 kernel/task_work.c:113 tracehook_notify_resume include/linux/tracehook.h:188 [inline] exit_to_usermode_loop+0x316/0x380 arch/x86/entry/common.c:164 prepare_exit_to_usermode arch/x86/entry/common.c:195 [inline] syscall_return_slowpath arch/x86/entry/common.c:278 [inline] do_syscall_64+0x676/0x790 arch/x86/entry/common.c:304 entry_SYSCALL_64_after_hwframe+0x49/0xbe RIP: 0033:0x448757 Code: Bad RIP value. RSP: 002b:00007ffcbb13cc08 EFLAGS: 00000202 ORIG_RAX: 00000000000000a6 RAX: 0000000000000000 RBX: 000000000004f2b3 RCX: 0000000000448757 RDX: 0000000000400c50 RSI: 0000000000000002 RDI: 00007ffcbb13ccb0 RBP: 0000000000002d93 R08: 0000000000000000 R09: 000000000000000b R10: 0000000000000005 R11: 0000000000000202 R12: 00007ffcbb13dd10 R13: 0000000002481940 R14: 0000000000000000 R15: 0000000000000000 Showing all locks held in the system: 1 lock held by khungtaskd/1134: #0: ffffffff89baf980 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 kernel/locking/lockdep.c:5334 1 lock held by rsyslogd/9631: #0: ffff8880a3044620 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 fs/file.c:803 2 locks held by getty/9721: #0: ffff8880a06a9090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000176b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9722: #0: ffff8880a8c32090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000197b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9723: #0: ffff888097737090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000195b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9724: #0: ffff888094a22090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000196b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9725: #0: ffff8880a786c090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000176f2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9726: #0: ffff888094ccc090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc9000193b2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by getty/9727: #0: ffff888214846090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 drivers/tty/tty_ldsem.c:340 #1: ffffc900011552e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 drivers/tty/n_tty.c:2156 2 locks held by syz-executor139/9745: #0: ffff88808fb160d8 (&type->s_umount_key#41){+.+.}, at: deactivate_super fs/super.c:365 [inline] #0: ffff88808fb160d8 (&type->s_umount_key#41){+.+.}, at: deactivate_super+0x1b5/0x1e0 fs/super.c:362 #1: ffff88808fb168b8 (&s->s_sync_lock){+.+.}, at: wait_sb_inodes fs/fs-writeback.c:2375 [inline] #1: ffff88808fb168b8 (&s->s_sync_lock){+.+.}, at: sync_inodes_sb+0x246/0xb50 fs/fs-writeback.c:2558 ============================================= NMI backtrace for cpu 0 CPU: 0 PID: 1134 Comm: khungtaskd Not tainted 5.5.0-rc2-next-20191220-syzkaller #0 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 Call Trace: __dump_stack lib/dump_stack.c:77 [inline] dump_stack+0x197/0x210 lib/dump_stack.c:118 nmi_cpu_backtrace.cold+0x70/0xb2 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x23b/0x28b lib/nmi_backtrace.c:62 arch_trigger_cpumask_backtrace+0x14/0x20 arch/x86/kernel/apic/hw_nmi.c:38 trigger_all_cpu_backtrace include/linux/nmi.h:146 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:249 [inline] watchdog+0xdf1/0x14e0 kernel/hung_task.c:333 kthread+0x361/0x430 kernel/kthread.c:255 ret_from_fork+0x24/0x30 arch/x86/entry/entry_64.S:352 Sending NMI from CPU 0 to CPUs 1: NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 arch/x86/include/asm/irqflags.h:60