[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 62.830745][ T26] audit: type=1800 audit(1572178211.737:25): pid=8535 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 62.851371][ T26] audit: type=1800 audit(1572178211.737:26): pid=8535 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 62.919702][ T26] audit: type=1800 audit(1572178211.747:27): pid=8535 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="restorecond" dev="sda1" ino=2436 res=0 [....] Starting periodic command scheduler: cron[?25l[?1c7[ ok 8[?25h[?0c. [....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[ ok 8[?25h[?0c. Debian GNU/Linux 7 syzkaller ttyS0 Warning: Permanently added '10.128.1.53' (ECDSA) to the list of known hosts. syzkaller login: [ 242.859513][ T1077] INFO: task khugepaged:1084 blocked for more than 143 seconds. [ 242.867423][ T1077] Not tainted 5.4.0-rc4-next-20191025 #0 [ 242.873648][ T1077] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 242.882365][ T1077] khugepaged D27848 1084 2 0x80004000 [ 242.888690][ T1077] Call Trace: [ 242.892108][ T1077] __schedule+0x94a/0x1e70 [ 242.896600][ T1077] ? __sched_text_start+0x8/0x8 [ 242.901530][ T1077] ? blk_insert_cloned_request+0x530/0x530 [ 242.907387][ T1077] ? _raw_spin_unlock_irq+0x23/0x80 [ 242.912637][ T1077] ? __lock_page+0x3d9/0xab0 [ 242.917237][ T1077] ? _raw_spin_unlock_irq+0x23/0x80 [ 242.922476][ T1077] schedule+0xdc/0x2b0 [ 242.926555][ T1077] io_schedule+0x1c/0x70 [ 242.930853][ T1077] __lock_page+0x422/0xab0 [ 242.935299][ T1077] ? wait_on_page_bit+0xa60/0xa60 [ 242.940460][ T1077] ? page_cache_next_miss+0x340/0x340 [ 242.945837][ T1077] ? ___might_sleep+0x163/0x2c0 [ 242.950735][ T1077] ? __might_sleep+0x95/0x190 [ 242.955418][ T1077] mpage_prepare_extent_to_map+0xb3f/0xf90 [ 242.961877][ T1077] ? mpage_process_page_bufs+0x780/0x780 [ 242.967564][ T1077] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 242.974363][ T1077] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 242.980666][ T1077] ext4_writepages+0xb6a/0x2e70 [ 242.985568][ T1077] ? __this_cpu_preempt_check+0x2c/0x190 [ 242.991990][ T1077] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 242.997441][ T1077] ? 0xffffffff81000000 [ 243.001636][ T1077] ? mark_lock+0xc2/0x1220 [ 243.006073][ T1077] ? prep_new_page+0x19f/0x200 [ 243.010903][ T1077] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 243.016888][ T1077] ? find_held_lock+0x35/0x130 [ 243.022412][ T1077] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 243.028397][ T1077] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 243.033908][ T1077] do_writepages+0xfa/0x2a0 [ 243.038934][ T1077] ? do_writepages+0xfa/0x2a0 [ 243.043672][ T1077] ? lock_downgrade+0x920/0x920 [ 243.048522][ T1077] ? page_writeback_cpu_online+0x20/0x20 [ 243.054194][ T1077] ? __kasan_check_read+0x11/0x20 [ 243.059221][ T1077] ? do_raw_spin_unlock+0x57/0x270 [ 243.065099][ T1077] ? _raw_spin_unlock+0x28/0x40 [ 243.070343][ T1077] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 243.076582][ T1077] ? wbc_attach_and_unlock_inode+0x5bf/0x920 [ 243.082608][ T1077] __filemap_fdatawrite_range+0x2bc/0x3b0 [ 243.088342][ T1077] ? delete_from_page_cache_batch+0xfe0/0xfe0 [ 243.094477][ T1077] ? lockdep_hardirqs_on+0x421/0x5e0 [ 243.099803][ T1077] filemap_flush+0x24/0x30 [ 243.104221][ T1077] collapse_file+0x36b1/0x41a0 [ 243.108970][ T1077] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 243.115902][ T1077] ? khugepaged+0x21d0/0x4360 [ 243.124460][ T1077] ? trace_event_raw_event_mm_collapse_huge_page_isolate+0x370/0x370 [ 243.132575][ T1077] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 243.138302][ T1077] ? khugepaged_find_target_node+0x142/0x180 [ 243.145461][ T1077] khugepaged+0x2da9/0x4360 [ 243.150292][ T1077] ? __kasan_check_read+0x11/0x20 [ 243.155884][ T1077] ? __lock_acquire+0x16f2/0x4a00 [ 243.160948][ T1077] ? _raw_spin_unlock_irq+0x23/0x80 [ 243.166148][ T1077] ? finish_task_switch+0x147/0x750 [ 243.172118][ T1077] ? _raw_spin_unlock_irq+0x23/0x80 [ 243.177320][ T1077] ? lockdep_hardirqs_on+0x421/0x5e0 [ 243.182675][ T1077] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 243.188307][ T1077] ? lock_downgrade+0x920/0x920 [ 243.193202][ T1077] ? finish_wait+0x260/0x260 [ 243.197988][ T1077] ? lockdep_hardirqs_on+0x421/0x5e0 [ 243.203364][ T1077] ? trace_hardirqs_on+0x67/0x240 [ 243.208402][ T1077] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 243.214715][ T1077] ? __kthread_parkme+0x108/0x1c0 [ 243.219874][ T1077] ? __kasan_check_read+0x11/0x20 [ 243.224901][ T1077] kthread+0x361/0x430 [ 243.229226][ T1077] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 243.234909][ T1077] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 243.241342][ T1077] ret_from_fork+0x24/0x30 [ 243.245862][ T1077] [ 243.245862][ T1077] Showing all locks held in the system: [ 243.255296][ T1077] 4 locks held by kworker/u4:2/102: [ 243.260618][ T1077] #0: ffff8880a7e70128 ((wq_completion)writeback){+.+.}, at: process_one_work+0x88b/0x1740 [ 243.290805][ T1077] #1: ffff8880a960fdc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 [ 243.302155][ T1077] #2: ffff8882159cc0d8 (&type->s_umount_key#32){++++}, at: trylock_super+0x22/0x110 [ 243.320552][ T1077] #3: ffff8882159ce990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 243.330466][ T1077] 1 lock held by khungtaskd/1077: [ 243.335490][ T1077] #0: ffffffff88faba80 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 [ 243.344860][ T1077] 1 lock held by khugepaged/1084: [ 243.349924][ T1077] #0: ffff8882159ce990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 243.360278][ T1077] 2 locks held by getty/8663: [ 243.364947][ T1077] #0: ffff888098f71090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.373944][ T1077] #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.383653][ T1077] 2 locks held by getty/8664: [ 243.388314][ T1077] #0: ffff8880a8b68090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.397312][ T1077] #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.408239][ T1077] 2 locks held by getty/8665: [ 243.413646][ T1077] #0: ffff88809a5cb090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.422872][ T1077] #1: ffffc90005f412e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.432604][ T1077] 2 locks held by getty/8666: [ 243.437285][ T1077] #0: ffff88809d54b090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.446329][ T1077] #1: ffffc90005f1d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.455933][ T1077] 2 locks held by getty/8667: [ 243.460648][ T1077] #0: ffff8880a393e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.469662][ T1077] #1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.479251][ T1077] 2 locks held by getty/8668: [ 243.483987][ T1077] #0: ffff88808da72090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.492977][ T1077] #1: ffffc90005f3d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.502684][ T1077] 2 locks held by getty/8669: [ 243.507649][ T1077] #0: ffff88809b0d5090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 243.517377][ T1077] #1: ffffc90005f092e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 243.527102][ T1077] 1 lock held by syz-execprog/8689: [ 243.532337][ T1077] #0: ffff8880970103a8 (&ei->i_mmap_sem){++++}, at: ext4_filemap_fault+0x7e/0xb2 [ 243.541624][ T1077] [ 243.543951][ T1077] ============================================= [ 243.543951][ T1077] [ 243.552392][ T1077] NMI backtrace for cpu 1 [ 243.556722][ T1077] CPU: 1 PID: 1077 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 243.567665][ T1077] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 243.577887][ T1077] Call Trace: [ 243.581177][ T1077] dump_stack+0x172/0x1f0 [ 243.585512][ T1077] nmi_cpu_backtrace.cold+0x70/0xb2 [ 243.590702][ T1077] ? vprintk_func+0x86/0x189 [ 243.595298][ T1077] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 243.600997][ T1077] nmi_trigger_cpumask_backtrace+0x23b/0x28b [ 243.606982][ T1077] arch_trigger_cpumask_backtrace+0x14/0x20 [ 243.612869][ T1077] watchdog+0xc8f/0x1350 [ 243.617538][ T1077] kthread+0x361/0x430 [ 243.621595][ T1077] ? reset_hung_task_detector+0x30/0x30 [ 243.628870][ T1077] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 243.634641][ T1077] ret_from_fork+0x24/0x30 [ 243.639167][ T1077] Sending NMI from CPU 1 to CPUs 0: [ 243.644487][ C0] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 [ 243.646202][ T1077] Kernel panic - not syncing: hung_task: blocked tasks [ 243.659593][ T1077] CPU: 1 PID: 1077 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 243.668159][ T1077] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 243.678196][ T1077] Call Trace: [ 243.681490][ T1077] dump_stack+0x172/0x1f0 [ 243.685809][ T1077] panic+0x2e3/0x75c [ 243.689682][ T1077] ? add_taint.cold+0x16/0x16 [ 243.694341][ T1077] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 243.699978][ T1077] ? ___preempt_schedule+0x16/0x18 [ 243.705087][ T1077] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 243.711227][ T1077] ? nmi_trigger_cpumask_backtrace+0x24c/0x28b [ 243.717373][ T1077] ? nmi_trigger_cpumask_backtrace+0x256/0x28b [ 243.723523][ T1077] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 243.729675][ T1077] watchdog+0xca0/0x1350 [ 243.733911][ T1077] kthread+0x361/0x430 [ 243.737967][ T1077] ? reset_hung_task_detector+0x30/0x30 [ 243.743490][ T1077] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 243.749200][ T1077] ret_from_fork+0x24/0x30 [ 243.756090][ T1077] Kernel Offset: disabled [ 243.760424][ T1077] Rebooting in 86400 seconds..