INFO: task hung in do_page_mkwriteINFO: task syz-fuzzer:4868 blocked for more than 140 seconds. Not tainted 4.19.0-rc2-next-20180905+ #57 "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. syz-fuzzer D21704 4868 4866 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: 0033:0x70b581 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: 00007f5d5ea47000 RDX: 0000000000000543 RSI: 000000000072a460 RDI: 000000c420031348 RBP: 000000c420031400 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000949c4a R11: 0000000000000004 R12: 0000000000000000 R13: 0000000000000020 R14: 0000000000000013 R15: 000000000000000f Showing all locks held in the system: 4 locks held by kworker/u4:2/41: #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: __write_once_size include/linux/compiler.h:215 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: arch_atomic64_set arch/x86/include/asm/atomic64_64.h:34 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: atomic64_set include/asm-generic/atomic-instrumented.h:40 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: atomic_long_set include/asm-generic/atomic-long.h:59 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: set_work_data kernel/workqueue.c:617 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: set_work_pool_and_clear_pending kernel/workqueue.c:644 [inline] #0: 000000002dc51066 ((wq_completion)"writeback"){+.+.}, at: process_one_work+0xb44/0x1aa0 kernel/workqueue.c:2124 #1: 0000000090cba0f6 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0xb9b/0x1aa0 kernel/workqueue.c:2128 #2: 000000004a799f2a (&fc->fs_type->s_umount_key#29){++++}, at: trylock_super+0x22/0x110 fs/super.c:411 #3: 0000000007800486 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0x9a/0x1a0 mm/page-writeback.c:2340 1 lock held by khungtaskd/793: #0: 0000000082e38aa8 (rcu_read_lock){....}, at: debug_show_all_locks+0xd0/0x428 kernel/locking/lockdep.c:4436 1 lock held by khugepaged/799: #0: 00000000e7f87b91 (&mm->mmap_sem){++++}, at: collapse_huge_page+0x2bf/0x2250 mm/khugepaged.c:1007 1 lock held by rsyslogd/4756: #0: 0000000030d80d1a (&f->f_pos_lock){+.+.}, at: __fdget_pos+0x1bb/0x200 fs/file.c:766 2 locks held by getty/4846: #0: 000000000a2bb201 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000027754d8 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4847: #0: 00000000a840976b (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000a78963a9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4848: #0: 00000000b33ab2f3 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000007acda6aa (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4849: #0: 00000000e8862c91 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 000000000bc10255 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4850: #0: 00000000850e505f (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000d32c5849 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4851: #0: 00000000d7dcc906 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000ad7236e9 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 2 locks held by getty/4852: #0: 0000000074bf3088 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x37/0x40 drivers/tty/tty_ldsem.c:353 #1: 00000000905ef677 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x335/0x1ce0 drivers/tty/n_tty.c:2140 1 lock held by syz-fuzzer/4868: #0: 00000000e7f87b91 (&mm->mmap_sem){++++}, at: __do_page_fault+0x389/0xe50 arch/x86/mm/fault.c:1324 1 lock held by syz-fuzzer/4872: #0: 000000003fcf37de (&rq->lock){-.-.}, at: rq_lock kernel/sched/sched.h:1821 [inline] #0: 000000003fcf37de (&rq->lock){-.-.}, at: __schedule+0x24d/0x1df0 kernel/sched/core.c:3411 ============================================= NMI backtrace for cpu 1 CPU: 1 PID: 793 Comm: khungtaskd Not tainted 4.19.0-rc2-next-20180905+ #57 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 skipped: idling at native_safe_halt+0x6/0x10 arch/x86/include/asm/irqflags.h:57