[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c.
[ 56.615676][ T26] audit: type=1800 audit(1572582295.275:25): pid=8620 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0
[ 56.635491][ T26] audit: type=1800 audit(1572582295.275:26): pid=8620 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0
[ 56.661939][ T26] audit: type=1800 audit(1572582295.285:27): pid=8620 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[1G[[32m ok [39;49m8[?25h[?0c.
[....] Starting OpenBSD Secure Shell server: sshd[?25l[?1c7[1G[[32m ok [39;49m8[?25h[?0c.
Debian GNU/Linux 7 syzkaller ttyS0
Warning: Permanently added '10.128.10.36' (ECDSA) to the list of known hosts.
syzkaller login: [ 216.572034][ T1079] INFO: task khugepaged:1086 blocked for more than 143 seconds.
[ 216.579859][ T1079] Not tainted 5.4.0-rc5-next-20191031 #0
[ 216.587065][ T1079] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message.
[ 216.595830][ T1079] khugepaged D27848 1086 2 0x80004000
[ 216.602217][ T1079] Call Trace:
[ 216.605510][ T1079] __schedule+0x94a/0x1e70
[ 216.609941][ T1079] ? __sched_text_start+0x8/0x8
[ 216.614853][ T1079] ? blk_insert_cloned_request+0x530/0x530
[ 216.620668][ T1079] ? _raw_spin_unlock_irq+0x23/0x80
[ 216.625926][ T1079] ? __lock_page+0x3d9/0xab0
[ 216.630527][ T1079] ? _raw_spin_unlock_irq+0x23/0x80
[ 216.635786][ T1079] schedule+0xdc/0x2b0
[ 216.639861][ T1079] io_schedule+0x1c/0x70
[ 216.644257][ T1079] __lock_page+0x422/0xab0
[ 216.648668][ T1079] ? wait_on_page_bit+0xa60/0xa60
[ 216.653746][ T1079] ? page_cache_next_miss+0x340/0x340
[ 216.659129][ T1079] ? ___might_sleep+0x163/0x2c0
[ 216.664037][ T1079] ? __might_sleep+0x95/0x190
[ 216.668712][ T1079] mpage_prepare_extent_to_map+0xb3f/0xf90
[ 216.674577][ T1079] ? mpage_process_page_bufs+0x780/0x780
[ 216.680233][ T1079] ? rcu_read_lock_any_held.part.0+0x50/0x50
[ 216.686274][ T1079] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[ 216.692580][ T1079] ext4_writepages+0xb6a/0x2e70
[ 216.698212][ T1079] ? get_page_from_freelist+0x21fb/0x4330
[ 216.703985][ T1079] ? find_held_lock+0x35/0x130
[ 216.708746][ T1079] ? get_page_from_freelist+0x21fb/0x4330
[ 216.715255][ T1079] ? ext4_mark_inode_dirty+0x9b0/0x9b0
[ 216.720714][ T1079] ? 0xffffffff81000000
[ 216.724921][ T1079] ? mark_lock+0xc2/0x1220
[ 216.729367][ T1079] ? prep_new_page+0x19f/0x200
[ 216.734191][ T1079] ? wbc_attach_and_unlock_inode+0x515/0x920
[ 216.740178][ T1079] ? find_held_lock+0x35/0x130
[ 216.744997][ T1079] ? wbc_attach_and_unlock_inode+0x515/0x920
[ 216.750985][ T1079] ? ext4_mark_inode_dirty+0x9b0/0x9b0
[ 216.756492][ T1079] do_writepages+0xfa/0x2a0
[ 216.762443][ T1079] ? do_writepages+0xfa/0x2a0
[ 216.767121][ T1079] ? lock_downgrade+0x920/0x920
[ 216.772017][ T1079] ? page_writeback_cpu_online+0x20/0x20
[ 216.777669][ T1079] ? __kasan_check_read+0x11/0x20
[ 216.782738][ T1079] ? do_raw_spin_unlock+0x57/0x270
[ 216.787857][ T1079] ? _raw_spin_unlock+0x28/0x40
[ 216.792765][ T1079] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20
[ 216.799004][ T1079] ? wbc_attach_and_unlock_inode+0x5bf/0x920
[ 216.805030][ T1079] __filemap_fdatawrite_range+0x2bc/0x3b0
[ 216.810752][ T1079] ? delete_from_page_cache_batch+0xfe0/0xfe0
[ 216.817443][ T1079] ? lockdep_hardirqs_on+0x421/0x5e0
[ 216.822795][ T1079] filemap_flush+0x24/0x30
[ 216.827220][ T1079] collapse_file+0x36b1/0x41a0
[ 216.832052][ T1079] ? khugepaged+0x21c0/0x4360
[ 216.836730][ T1079] ? trace_event_raw_event_mm_collapse_huge_page_isolate+0x370/0x370
[ 216.845578][ T1079] ? rcu_preempt_deferred_qs_irqrestore+0x4ff/0xd60
[ 216.852235][ T1079] ? __sanitizer_cov_trace_cmp4+0x16/0x20
[ 216.857964][ T1079] ? khugepaged_find_target_node+0x142/0x180
[ 216.864007][ T1079] khugepaged+0x2da9/0x4360
[ 216.868521][ T1079] ? __kasan_check_read+0x11/0x20
[ 216.873579][ T1079] ? __lock_acquire+0x16f2/0x4a00
[ 216.878614][ T1079] ? _raw_spin_unlock_irq+0x23/0x80
[ 216.883861][ T1079] ? finish_task_switch+0x147/0x750
[ 216.889065][ T1079] ? _raw_spin_unlock_irq+0x23/0x80
[ 216.894380][ T1079] ? lockdep_hardirqs_on+0x421/0x5e0
[ 216.899674][ T1079] ? collapse_pte_mapped_thp+0xbe0/0xbe0
[ 216.905346][ T1079] ? lock_downgrade+0x920/0x920
[ 216.910212][ T1079] ? finish_wait+0x260/0x260
[ 216.914835][ T1079] ? lockdep_hardirqs_on+0x421/0x5e0
[ 216.920129][ T1079] ? trace_hardirqs_on+0x67/0x240
[ 216.925218][ T1079] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20
[ 216.931460][ T1079] ? __kthread_parkme+0x108/0x1c0
[ 216.936527][ T1079] ? __kasan_check_read+0x11/0x20
[ 216.941561][ T1079] kthread+0x361/0x430
[ 216.945686][ T1079] ? collapse_pte_mapped_thp+0xbe0/0xbe0
[ 216.951317][ T1079] ? kthread_mod_delayed_work+0x1f0/0x1f0
[ 216.957093][ T1079] ret_from_fork+0x24/0x30
[ 216.961628][ T1079]
[ 216.961628][ T1079] Showing all locks held in the system:
[ 216.969408][ T1079] 4 locks held by kworker/u4:0/7:
[ 216.975140][ T1079] #0: ffff8880a7dfc928 ((wq_completion)writeback){+.+.}, at: process_one_work+0x88b/0x1740
[ 216.985289][ T1079] #1: ffff8880a988fdc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x8c1/0x1740
[ 216.996634][ T1079] #2: ffff88809ad2e0d8 (&type->s_umount_key#32){++++}, at: trylock_super+0x22/0x110
[ 217.006174][ T1079] #3: ffff88809ad30990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0
[ 217.016068][ T1079] 1 lock held by khungtaskd/1079:
[ 217.021072][ T1079] #0: ffffffff88faba40 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279
[ 217.030442][ T1079] 1 lock held by khugepaged/1086:
[ 217.035499][ T1079] #0: ffff88809ad30990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0
[ 217.045675][ T1079] 1 lock held by rsyslogd/8658:
[ 217.050534][ T1079] #0: ffff8880a1f601a0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110
[ 217.059420][ T1079] 2 locks held by getty/8748:
[ 217.064279][ T1079] #0: ffff88809a003090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.073283][ T1079] #1: ffffc90005f092e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.083003][ T1079] 2 locks held by getty/8749:
[ 217.087673][ T1079] #0: ffff888093b39090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.096798][ T1079] #1: ffffc90005f312e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.107097][ T1079] 2 locks held by getty/8750:
[ 217.111763][ T1079] #0: ffff888091435090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.120752][ T1079] #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.130363][ T1079] 2 locks held by getty/8751:
[ 217.135082][ T1079] #0: ffff888091d2f090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.144093][ T1079] #1: ffffc90005f2d2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.153701][ T1079] 2 locks held by getty/8752:
[ 217.158366][ T1079] #0: ffff8880a8a60090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.167392][ T1079] #1: ffffc90005f112e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.177018][ T1079] 2 locks held by getty/8753:
[ 217.181697][ T1079] #0: ffff8880a4f56090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.191060][ T1079] #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.200960][ T1079] 2 locks held by getty/8754:
[ 217.205713][ T1079] #0: ffff88808ea55090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40
[ 217.214725][ T1079] #1: ffffc90005ef92e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0
[ 217.224414][ T1079] 1 lock held by syz-execprog/8776:
[ 217.229645][ T1079] #0: ffff8880a32f33a8 (&ei->i_mmap_sem){++++}, at: ext4_filemap_fault+0x7e/0xb2
[ 217.239638][ T1079]
[ 217.242014][ T1079] =============================================
[ 217.242014][ T1079]
[ 217.250418][ T1079] NMI backtrace for cpu 0
[ 217.254794][ T1079] CPU: 0 PID: 1079 Comm: khungtaskd Not tainted 5.4.0-rc5-next-20191031 #0
[ 217.263432][ T1079] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 217.273481][ T1079] Call Trace:
[ 217.276763][ T1079] dump_stack+0x172/0x1f0
[ 217.281090][ T1079] nmi_cpu_backtrace.cold+0x70/0xb2
[ 217.286286][ T1079] ? vprintk_func+0x86/0x189
[ 217.290892][ T1079] ? lapic_can_unplug_cpu.cold+0x3a/0x3a
[ 217.296515][ T1079] nmi_trigger_cpumask_backtrace+0x23b/0x28b
[ 217.302490][ T1079] arch_trigger_cpumask_backtrace+0x14/0x20
[ 217.308366][ T1079] watchdog+0xc8f/0x1350
[ 217.312603][ T1079] kthread+0x361/0x430
[ 217.316661][ T1079] ? reset_hung_task_detector+0x30/0x30
[ 217.322202][ T1079] ? kthread_mod_delayed_work+0x1f0/0x1f0
[ 217.327969][ T1079] ret_from_fork+0x24/0x30
[ 217.332452][ T1079] Sending NMI from CPU 0 to CPUs 1:
[ 217.337704][ C1] NMI backtrace for cpu 1 skipped: idling at native_safe_halt+0xe/0x10
[ 217.338650][ T1079] Kernel panic - not syncing: hung_task: blocked tasks
[ 217.352799][ T1079] CPU: 0 PID: 1079 Comm: khungtaskd Not tainted 5.4.0-rc5-next-20191031 #0
[ 217.361372][ T1079] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011
[ 217.371438][ T1079] Call Trace:
[ 217.374729][ T1079] dump_stack+0x172/0x1f0
[ 217.379069][ T1079] panic+0x2e3/0x75c
[ 217.382957][ T1079] ? add_taint.cold+0x16/0x16
[ 217.387647][ T1079] ? __sanitizer_cov_trace_cmp4+0x16/0x20
[ 217.393354][ T1079] ? printk_safe_flush+0xf2/0x140
[ 217.398363][ T1079] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20
[ 217.404601][ T1079] ? nmi_trigger_cpumask_backtrace+0x224/0x28b
[ 217.410776][ T1079] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b
[ 217.417027][ T1079] watchdog+0xca0/0x1350
[ 217.421293][ T1079] kthread+0x361/0x430
[ 217.425372][ T1079] ? reset_hung_task_detector+0x30/0x30
[ 217.430912][ T1079] ? kthread_mod_delayed_work+0x1f0/0x1f0
[ 217.436627][ T1079] ret_from_fork+0x24/0x30
[ 217.442515][ T1079] Kernel Offset: disabled
[ 217.446850][ T1079] Rebooting in 86400 seconds..