[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 55.965621][ T26] audit: type=1800 audit(1572173799.380:25): pid=8668 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 55.986350][ T26] audit: type=1800 audit(1572173799.380:26): pid=8668 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 56.007293][ T26] audit: type=1800 audit(1572173799.390:27): pid=8668 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 '10.128.0.179' (ECDSA) to the list of known hosts. syzkaller login: [ 215.234629][ T1078] INFO: task khugepaged:1086 blocked for more than 143 seconds. [ 215.242583][ T1078] Not tainted 5.4.0-rc4-next-20191025 #0 [ 215.248992][ T1078] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 215.257731][ T1078] khugepaged D27840 1086 2 0x80004000 [ 215.264079][ T1078] Call Trace: [ 215.267455][ T1078] __schedule+0x94a/0x1e70 [ 215.271901][ T1078] ? __sched_text_start+0x8/0x8 [ 215.276816][ T1078] ? blk_insert_cloned_request+0x530/0x530 [ 215.282644][ T1078] ? _raw_spin_unlock_irq+0x23/0x80 [ 215.288610][ T1078] ? __lock_page+0x3d9/0xab0 [ 215.293431][ T1078] ? _raw_spin_unlock_irq+0x23/0x80 [ 215.298713][ T1078] schedule+0xdc/0x2b0 [ 215.302804][ T1078] io_schedule+0x1c/0x70 [ 215.307111][ T1078] __lock_page+0x422/0xab0 [ 215.311659][ T1078] ? wait_on_page_bit+0xa60/0xa60 [ 215.316785][ T1078] ? page_cache_next_miss+0x340/0x340 [ 215.322182][ T1078] ? ___might_sleep+0x163/0x2c0 [ 215.327124][ T1078] ? __might_sleep+0x95/0x190 [ 215.331825][ T1078] mpage_prepare_extent_to_map+0xb3f/0xf90 [ 215.337723][ T1078] ? mpage_process_page_bufs+0x780/0x780 [ 215.343379][ T1078] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 215.349413][ T1078] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 215.355726][ T1078] ext4_writepages+0xb6a/0x2e70 [ 215.360606][ T1078] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 215.366135][ T1078] ? 0xffffffff81000000 [ 215.370315][ T1078] ? mark_lock+0xc2/0x1220 [ 215.374797][ T1078] ? prep_new_page+0x19f/0x200 [ 215.379586][ T1078] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 215.385611][ T1078] ? find_held_lock+0x35/0x130 [ 215.390401][ T1078] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 215.396459][ T1078] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 215.402075][ T1078] do_writepages+0xfa/0x2a0 [ 215.406776][ T1078] ? do_writepages+0xfa/0x2a0 [ 215.411477][ T1078] ? lock_downgrade+0x920/0x920 [ 215.417154][ T1078] ? page_writeback_cpu_online+0x20/0x20 [ 215.422807][ T1078] ? __kasan_check_read+0x11/0x20 [ 215.427877][ T1078] ? do_raw_spin_unlock+0x57/0x270 [ 215.433148][ T1078] ? _raw_spin_unlock+0x28/0x40 [ 215.438105][ T1078] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 215.444715][ T1078] ? wbc_attach_and_unlock_inode+0x5bf/0x920 [ 215.450904][ T1078] __filemap_fdatawrite_range+0x2bc/0x3b0 [ 215.456881][ T1078] ? delete_from_page_cache_batch+0xfe0/0xfe0 [ 215.463167][ T1078] ? lockdep_hardirqs_on+0x421/0x5e0 [ 215.468518][ T1078] filemap_flush+0x24/0x30 [ 215.472956][ T1078] collapse_file+0x36b1/0x41a0 [ 215.477790][ T1078] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 215.483962][ T1078] ? khugepaged+0x21d0/0x4360 [ 215.488696][ T1078] ? trace_event_raw_event_mm_collapse_huge_page_isolate+0x370/0x370 [ 215.496849][ T1078] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 215.502958][ T1078] ? khugepaged_find_target_node+0x142/0x180 [ 215.509164][ T1078] khugepaged+0x2da9/0x4360 [ 215.513702][ T1078] ? __kasan_check_read+0x11/0x20 [ 215.518814][ T1078] ? __lock_acquire+0x16f2/0x4a00 [ 215.523865][ T1078] ? _raw_spin_unlock_irq+0x23/0x80 [ 215.529114][ T1078] ? finish_task_switch+0x147/0x750 [ 215.534425][ T1078] ? _raw_spin_unlock_irq+0x23/0x80 [ 215.539728][ T1078] ? lockdep_hardirqs_on+0x421/0x5e0 [ 215.545764][ T1078] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 215.551412][ T1078] ? lock_downgrade+0x920/0x920 [ 215.556397][ T1078] ? finish_wait+0x260/0x260 [ 215.561063][ T1078] ? lockdep_hardirqs_on+0x421/0x5e0 [ 215.566409][ T1078] ? trace_hardirqs_on+0x67/0x240 [ 215.571445][ T1078] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 215.577756][ T1078] ? __kthread_parkme+0x108/0x1c0 [ 215.582815][ T1078] ? __kasan_check_read+0x11/0x20 [ 215.588060][ T1078] kthread+0x361/0x430 [ 215.592147][ T1078] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 215.597892][ T1078] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 215.603635][ T1078] ret_from_fork+0x24/0x30 [ 215.608191][ T1078] [ 215.608191][ T1078] Showing all locks held in the system: [ 215.616405][ T1078] 4 locks held by kworker/u4:2/95: [ 215.621509][ T1078] #0: ffff8880a7b2ed28 ((wq_completion)writeback){+.+.}, at: process_one_work+0x88b/0x1740 [ 215.631629][ T1078] #1: ffff8880a95c7dc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 [ 215.642986][ T1078] #2: ffff88809b65a0d8 (&type->s_umount_key#32){++++}, at: trylock_super+0x22/0x110 [ 215.652498][ T1078] #3: ffff88809b65c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 215.662390][ T1078] 1 lock held by khungtaskd/1078: [ 215.667445][ T1078] #0: ffffffff88faba80 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 [ 215.677486][ T1078] 1 lock held by khugepaged/1086: [ 215.682507][ T1078] #0: ffff88809b65c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 215.692388][ T1078] 1 lock held by rsyslogd/8706: [ 215.697346][ T1078] #0: ffff888096129420 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 [ 215.705985][ T1078] 2 locks held by getty/8796: [ 215.710665][ T1078] #0: ffff8880a06fa090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.719772][ T1078] #1: ffffc90005f192e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.729451][ T1078] 2 locks held by getty/8797: [ 215.734120][ T1078] #0: ffff88809aa87090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.743272][ T1078] #1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.753042][ T1078] 2 locks held by getty/8798: [ 215.757847][ T1078] #0: ffff88809540e090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.766841][ T1078] #1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.776477][ T1078] 2 locks held by getty/8799: [ 215.781262][ T1078] #0: ffff8880954f9090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.790250][ T1078] #1: ffffc90005f352e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.799881][ T1078] 2 locks held by getty/8800: [ 215.805307][ T1078] #0: ffff8880a0c06090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.814268][ T1078] #1: ffffc90005f392e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.823889][ T1078] 2 locks held by getty/8801: [ 215.828704][ T1078] #0: ffff888097c4a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.837745][ T1078] #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.847357][ T1078] 2 locks held by getty/8802: [ 215.852031][ T1078] #0: ffff88809a993090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 215.861066][ T1078] #1: ffffc90005f012e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 215.870701][ T1078] 1 lock held by syz-execprog/8820: [ 215.875946][ T1078] #0: ffff8880ae934d58 (&rq->lock){-.-.}, at: __schedule+0x266/0x1e70 [ 215.884214][ T1078] 1 lock held by syz-execprog/8822: [ 215.889464][ T1078] #0: ffff88809085b368 (&ei->i_mmap_sem){++++}, at: ext4_filemap_fault+0x7e/0xb2 [ 215.898819][ T1078] [ 215.901135][ T1078] ============================================= [ 215.901135][ T1078] [ 215.909656][ T1078] NMI backtrace for cpu 0 [ 215.914007][ T1078] CPU: 0 PID: 1078 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 215.922602][ T1078] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 215.932667][ T1078] Call Trace: [ 215.935963][ T1078] dump_stack+0x172/0x1f0 [ 215.940301][ T1078] nmi_cpu_backtrace.cold+0x70/0xb2 [ 215.945507][ T1078] ? vprintk_func+0x86/0x189 [ 215.950211][ T1078] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 215.955861][ T1078] nmi_trigger_cpumask_backtrace+0x23b/0x28b [ 215.961871][ T1078] arch_trigger_cpumask_backtrace+0x14/0x20 [ 215.967768][ T1078] watchdog+0xc8f/0x1350 [ 215.972052][ T1078] kthread+0x361/0x430 [ 215.976139][ T1078] ? reset_hung_task_detector+0x30/0x30 [ 215.981675][ T1078] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 215.987380][ T1078] ret_from_fork+0x24/0x30 [ 215.991951][ T1078] Sending NMI from CPU 0 to CPUs 1: [ 215.997256][ C1] NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10 [ 215.998981][ T1078] Kernel panic - not syncing: hung_task: blocked tasks [ 216.012357][ T1078] CPU: 0 PID: 1078 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 216.020931][ T1078] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 216.030972][ T1078] Call Trace: [ 216.034271][ T1078] dump_stack+0x172/0x1f0 [ 216.038598][ T1078] panic+0x2e3/0x75c [ 216.042484][ T1078] ? add_taint.cold+0x16/0x16 [ 216.047150][ T1078] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 216.052805][ T1078] ? ___preempt_schedule+0x16/0x18 [ 216.057905][ T1078] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 216.064052][ T1078] ? nmi_trigger_cpumask_backtrace+0x24c/0x28b [ 216.070195][ T1078] ? nmi_trigger_cpumask_backtrace+0x256/0x28b [ 216.076340][ T1078] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 216.082484][ T1078] watchdog+0xca0/0x1350 [ 216.086721][ T1078] kthread+0x361/0x430 [ 216.090775][ T1078] ? reset_hung_task_detector+0x30/0x30 [ 216.096319][ T1078] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 216.102024][ T1078] ret_from_fork+0x24/0x30 [ 216.108077][ T1078] Kernel Offset: disabled [ 216.112445][ T1078] Rebooting in 86400 seconds..