INFO: task hung in do_page_mkwriteINFO: task syz-fuzzer:4925 blocked for more than 140 seconds. Not tainted 4.19.0-rc2-next-20180905+ #56 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-fuzzer D21000 4925 4918 0x00000000 Call Trace: context_switch kernel/sched/core.c:2825 [inline] __schedule+0x87c/0x1df0 kernel/sched/core.c:3473 schedule+0xfb/0x450 kernel/sched/core.c:3517 io_schedule+0x1c/0x70 kernel/sched/core.c:5140 wait_on_page_bit_common mm/filemap.c:1100 [inline] __lock_page+0x5b7/0x7a0 mm/filemap.c:1273 lock_page include/linux/pagemap.h:483 [inline] do_page_mkwrite+0x429/0x520 mm/memory.c:2391 do_shared_fault mm/memory.c:3717 [inline] do_fault mm/memory.c:3756 [inline] handle_pte_fault mm/memory.c:3983 [inline] __handle_mm_fault+0x2a0a/0x4350 mm/memory.c:4107 handle_mm_fault+0x53e/0xc80 mm/memory.c:4144 __do_page_fault+0x620/0xe50 arch/x86/mm/fault.c:1395 do_page_fault+0xf6/0x7a4 arch/x86/mm/fault.c:1470 page_fault+0x1e/0x30 arch/x86/entry/entry_64.S:1164 RIP: 0033:0x70b591 Code: 48 89 6c 24 10 48 8d 6c 24 10 48 8b 44 24 20 48 8b 48 08 48 8b 50 10 48 8d 58 08 48 83 fa 08 0f 8c 1e 01 00 00 48 8b 54 24 28 <88> 11 48 8b 48 08 48 8b 70 10 48 83 fe 01 0f 86 44 01 00 00 48 89 RSP: 002b:000000c4200313f0 EFLAGS: 00010212 RAX: 000000c420031508 RBX: 000000c420031510 RCX: 00007f90bac4e000 RDX: 0000000000000537 RSI: 000000000072a470 RDI: 000000c420031348 RBP: 000000c420031400 R08: 0000000000000000 R09: 0000000000000000 R10: 00000000009496ca R11: 0000000000000004 R12: 0000000000000000 R13: 0000000000000020 R14: 0000000000000013 R15: 000000000000000f Showing all locks held in the system: 4 locks held by kworker/u4:3/134: #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 00000000e0bfa010 ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xb44/0x1aa0 kernel/workqueue.c:2124 #1: 000000006a1794bd ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb9b/0x1aa0 kernel/workqueue.c:2128 #2: 000000006cefa6ed (&fc->fs_type->s_umount_key#29){++++}, at: trylock_super+0x22/0x110 fs/super.c:411 #3: 000000007e4b3c28 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0x9a/0x1a0 mm/page-writeback.c:2340 1 lock held by khungtaskd/792: #0: 00000000ef98dca6 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4436 1 lock held by khugepaged/799: #0: 0000000019c0cdf4 (&mm->mmap_sem){++++}, at: collapse_huge_page+0x2bf/0x2250 mm/khugepaged.c:1007 1 lock held by rsyslogd/4806: #0: 00000000e45ad4d1 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/4896: #0: 00000000b0d63840 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000084e5ea07 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4897: #0: 000000001c573826 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000fd92ad9b (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4898: #0: 0000000092ce3f74 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 0000000003e57a0d (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4899: #0: 00000000fdf64db6 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000853b1f37 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4900: #0: 0000000063017494 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000f83e49dd (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4901: #0: 00000000526add4a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000e0c0e4d5 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4902: #0: 00000000e4a3225a (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000008b8fb769 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-fuzzer/4925: #0: 0000000019c0cdf4 (&mm->mmap_sem){++++}, at: __do_page_fault+0x389/0xe50 arch/x86/mm/fault.c:1324 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 792 Comm: khungtaskd Not tainted 4.19.0-rc2-next-20180905+ #56 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+0x1c9/0x2b4 lib/dump_stack.c:113 nmi_cpu_backtrace.cold.4+0x48/0x88 lib/nmi_backtrace.c:101 nmi_trigger_cpumask_backtrace+0x1b6/0x1cd 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:144 [inline] check_hung_uninterruptible_tasks kernel/hung_task.c:204 [inline] watchdog+0xb39/0x1040 kernel/hung_task.c:265 kthread+0x35a/0x420 kernel/kthread.c:246 ret_from_fork+0x3a/0x50 arch/x86/entry/entry_64.S:415 Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 PID: 0 Comm: swapper/0 Not tainted 4.19.0-rc2-next-20180905+ #56 Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 RIP: 0010:rcu_sched_qs+0x0/0x150 kernel/rcu/tree.c:213 Code: 83 c4 68 5b 41 5c 41 5d 5d c3 e8 eb 15 54 00 eb a8 48 89 45 80 e8 80 16 54 00 48 8b 45 80 eb b9 e8 95 c0 df ff 0f 1f 44 00 00 <55> 48 89 e5 53 48 83 ec 08 e8 d2 a0 fe ff 85 c0 74 0d 80 3d aa 73 RSP: 0018:ffffffff88007930 EFLAGS: 00000002 RAX: 0000000000000001 RBX: 1ffffffff1000f28 RCX: 0000000000000000 RDX: 1ffffffff10237d5 RSI: 00000000ffffffff RDI: 0000000000000082 RBP: ffffffff88007ac8 R08: ffffed003b6046df R09: ffffed003b6046de R10: ffffed003b6046de R11: ffff8801db0236f3 R12: ffffffff88007960 R13: ffffffff88007aa0 R14: 0000000000023700 R15: ffff8801db02cc80 FS: 0000000000000000(0000) GS:ffff8801db000000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: ffffffffff600400 CR3: 00000001d9685000 CR4: 00000000001406f0 DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400 Call Trace: __schedule+0x245/0x1df0 kernel/sched/core.c:3401 schedule_idle+0x45/0x80 kernel/sched/core.c:3544 do_idle+0x17f/0x580 kernel/sched/idle.c:286 cpu_startup_entry+0x10c/0x120 kernel/sched/idle.c:368 rest_init+0xe1/0xe4 init/main.c:442 start_kernel+0x8f9/0x934 init/main.c:739 x86_64_start_reservations+0x29/0x2b arch/x86/kernel/head64.c:452 x86_64_start_kernel+0x76/0x79 arch/x86/kernel/head64.c:433 secondary_startup_64+0xa4/0xb0 arch/x86/kernel/head_64.S:242