[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 57.177179][ T23] audit: type=1800 audit(1572202708.973:25): pid=8563 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 57.243673][ T23] audit: type=1800 audit(1572202708.973:26): pid=8563 uid=0 auid=4294967295 ses=4294967295 subj==unconfined op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 57.276506][ T23] audit: type=1800 audit(1572202708.973:27): pid=8563 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 '10.128.0.32' (ECDSA) to the list of known hosts. syzkaller login: [ 237.562410][ T955] INFO: task kworker/u4:1:21 blocked for more than 143 seconds. [ 237.570616][ T955] Not tainted 5.4.0-rc4-next-20191025 #0 [ 237.578247][ T955] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 237.587310][ T955] kworker/u4:1 D24344 21 2 0x80004000 [ 237.593725][ T955] Workqueue: writeback wb_workfn (flush-8:0) [ 237.599725][ T955] Call Trace: [ 237.603114][ T955] __schedule+0x94a/0x1e70 [ 237.607644][ T955] ? __sched_text_start+0x8/0x8 [ 237.613103][ T955] ? blk_insert_cloned_request+0x530/0x530 [ 237.618922][ T955] ? __sanitizer_cov_trace_const_cmp4+0x16/0x20 [ 237.625215][ T955] ? kthread_data+0x58/0xc0 [ 237.629740][ T955] schedule+0xdc/0x2b0 [ 237.633904][ T955] io_schedule+0x1c/0x70 [ 237.638167][ T955] __lock_page+0x422/0xab0 [ 237.642659][ T955] ? wait_on_page_bit+0xa60/0xa60 [ 237.647741][ T955] ? page_cache_next_miss+0x340/0x340 [ 237.653200][ T955] ? ___might_sleep+0x163/0x2c0 [ 237.658065][ T955] ? __might_sleep+0x95/0x190 [ 237.662916][ T955] mpage_prepare_extent_to_map+0xb3f/0xf90 [ 237.668749][ T955] ? mpage_process_page_bufs+0x780/0x780 [ 237.674475][ T955] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 237.680255][ T955] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 237.686354][ T955] ? kmem_cache_alloc_node_trace+0x4ef/0x750 [ 237.692435][ T955] ext4_writepages+0x954/0x2e70 [ 237.697434][ T955] ? ___might_sleep+0x163/0x2c0 [ 237.703149][ T955] ? __might_sleep+0x80/0x190 [ 237.707858][ T955] ? print_usage_bug+0xb1/0xd0 [ 237.712693][ T955] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 237.718166][ T955] ? __kasan_check_read+0x11/0x20 [ 237.723267][ T955] ? __lock_acquire+0x16f2/0x4a00 [ 237.728306][ T955] ? __kasan_check_read+0x11/0x20 [ 237.733466][ T955] ? mark_lock+0xc2/0x1220 [ 237.737899][ T955] ? mark_held_locks+0xf0/0xf0 [ 237.742729][ T955] ? __kasan_check_read+0x11/0x20 [ 237.747768][ T955] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 237.753341][ T955] do_writepages+0xfa/0x2a0 [ 237.757876][ T955] ? do_writepages+0xfa/0x2a0 [ 237.762678][ T955] ? page_writeback_cpu_online+0x20/0x20 [ 237.768328][ T955] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 237.774582][ T955] ? rcu_read_lock_sched_held+0x9c/0xd0 [ 237.780206][ T955] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 237.786267][ T955] __writeback_single_inode+0x136/0x1400 [ 237.791993][ T955] ? _raw_spin_unlock+0x28/0x40 [ 237.796933][ T955] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 237.803335][ T955] ? wbc_attach_and_unlock_inode+0x5bf/0x920 [ 237.809477][ T955] writeback_sb_inodes+0x596/0xf20 [ 237.814679][ T955] ? __writeback_single_inode+0x1400/0x1400 [ 237.820596][ T955] ? trylock_super+0x22/0x110 [ 237.825367][ T955] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 237.831627][ T955] __writeback_inodes_wb+0xc3/0x260 [ 237.837640][ T955] wb_writeback+0x910/0xd90 [ 237.842159][ T955] ? mark_lock+0xc2/0x1220 [ 237.846641][ T955] ? writeback_inodes_wb.constprop.0+0x1a0/0x1a0 [ 237.853038][ T955] ? __sanitizer_cov_trace_cmp8+0x18/0x20 [ 237.858775][ T955] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 237.864550][ T955] ? get_nr_dirty_inodes+0xe2/0x140 [ 237.869772][ T955] wb_workfn+0xba5/0x1220 [ 237.874205][ T955] ? inode_wait_for_writeback+0x40/0x40 [ 237.879770][ T955] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 237.886015][ T955] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 237.892016][ T955] ? trace_hardirqs_on+0x67/0x240 [ 237.897118][ T955] process_one_work+0x9af/0x1740 [ 237.902095][ T955] ? pwq_dec_nr_in_flight+0x320/0x320 [ 237.907598][ T955] ? lock_acquire+0x190/0x410 [ 237.912369][ T955] worker_thread+0x98/0xe40 [ 237.916904][ T955] kthread+0x361/0x430 [ 237.921079][ T955] ? process_one_work+0x1740/0x1740 [ 237.926357][ T955] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 237.932094][ T955] ret_from_fork+0x24/0x30 [ 237.936608][ T955] INFO: task khugepaged:961 blocked for more than 143 seconds. [ 237.944205][ T955] Not tainted 5.4.0-rc4-next-20191025 #0 [ 237.950361][ T955] "echo 0 > /proc/sys/kernel/hung_task_timeout_secs" disables this message. [ 237.959117][ T955] khugepaged D27456 961 2 0x80004000 [ 237.966283][ T955] Call Trace: [ 237.969578][ T955] __schedule+0x94a/0x1e70 [ 237.974073][ T955] ? __sched_text_start+0x8/0x8 [ 237.978941][ T955] ? blk_insert_cloned_request+0x530/0x530 [ 237.984807][ T955] ? _raw_spin_unlock_irq+0x23/0x80 [ 237.990024][ T955] ? __lock_page+0x3d9/0xab0 [ 237.994687][ T955] ? _raw_spin_unlock_irq+0x23/0x80 [ 237.999916][ T955] schedule+0xdc/0x2b0 [ 238.004049][ T955] io_schedule+0x1c/0x70 [ 238.008312][ T955] __lock_page+0x422/0xab0 [ 238.012804][ T955] ? wait_on_page_bit+0xa60/0xa60 [ 238.017855][ T955] ? page_cache_next_miss+0x340/0x340 [ 238.023288][ T955] ? ___might_sleep+0x163/0x2c0 [ 238.028175][ T955] ? __might_sleep+0x95/0x190 [ 238.032933][ T955] mpage_prepare_extent_to_map+0xb3f/0xf90 [ 238.038777][ T955] ? mpage_process_page_bufs+0x780/0x780 [ 238.044549][ T955] ? rcu_read_lock_any_held.part.0+0x50/0x50 [ 238.050567][ T955] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 238.056979][ T955] ext4_writepages+0xb6a/0x2e70 [ 238.061917][ T955] ? get_page_from_freelist+0x21fb/0x4330 [ 238.067709][ T955] ? find_held_lock+0x35/0x130 [ 238.072665][ T955] ? get_page_from_freelist+0x21fb/0x4330 [ 238.078423][ T955] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 238.083971][ T955] ? 0xffffffff81000000 [ 238.088138][ T955] ? mark_lock+0xc2/0x1220 [ 238.093368][ T955] ? prep_new_page+0x19f/0x200 [ 238.098142][ T955] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 238.104176][ T955] ? find_held_lock+0x35/0x130 [ 238.108963][ T955] ? wbc_attach_and_unlock_inode+0x515/0x920 [ 238.115010][ T955] ? ext4_mark_inode_dirty+0x9b0/0x9b0 [ 238.120479][ T955] do_writepages+0xfa/0x2a0 [ 238.125125][ T955] ? do_writepages+0xfa/0x2a0 [ 238.129819][ T955] ? lock_downgrade+0x920/0x920 [ 238.134740][ T955] ? page_writeback_cpu_online+0x20/0x20 [ 238.140491][ T955] ? __kasan_check_read+0x11/0x20 [ 238.145572][ T955] ? do_raw_spin_unlock+0x57/0x270 [ 238.150702][ T955] ? _raw_spin_unlock+0x28/0x40 [ 238.155612][ T955] ? __sanitizer_cov_trace_const_cmp8+0x18/0x20 [ 238.161881][ T955] ? wbc_attach_and_unlock_inode+0x5bf/0x920 [ 238.167925][ T955] __filemap_fdatawrite_range+0x2bc/0x3b0 [ 238.173762][ T955] ? delete_from_page_cache_batch+0xfe0/0xfe0 [ 238.179861][ T955] ? lockdep_hardirqs_on+0x421/0x5e0 [ 238.185224][ T955] filemap_flush+0x24/0x30 [ 238.189652][ T955] collapse_file+0x36b1/0x41a0 [ 238.194482][ T955] ? rcu_lockdep_current_cpu_online+0xe3/0x130 [ 238.201652][ T955] ? khugepaged+0x21d0/0x4360 [ 238.206418][ T955] ? trace_event_raw_event_mm_collapse_huge_page_isolate+0x370/0x370 [ 238.214556][ T955] ? __sanitizer_cov_trace_cmp4+0x16/0x20 [ 238.220288][ T955] ? khugepaged_find_target_node+0x142/0x180 [ 238.227246][ T955] khugepaged+0x2da9/0x4360 [ 238.231885][ T955] ? __kasan_check_read+0x11/0x20 [ 238.237057][ T955] ? __lock_acquire+0x16f2/0x4a00 [ 238.242226][ T955] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 238.247942][ T955] ? lock_downgrade+0x920/0x920 [ 238.253198][ T955] ? finish_wait+0x260/0x260 [ 238.257812][ T955] ? lockdep_hardirqs_on+0x421/0x5e0 [ 238.263289][ T955] ? trace_hardirqs_on+0x67/0x240 [ 238.268382][ T955] ? __sanitizer_cov_trace_const_cmp1+0x1a/0x20 [ 238.274712][ T955] ? __kthread_parkme+0x108/0x1c0 [ 238.279762][ T955] ? __kasan_check_read+0x11/0x20 [ 238.284877][ T955] kthread+0x361/0x430 [ 238.288969][ T955] ? collapse_pte_mapped_thp+0xbe0/0xbe0 [ 238.294664][ T955] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 238.300410][ T955] ret_from_fork+0x24/0x30 [ 238.304993][ T955] [ 238.304993][ T955] Showing all locks held in the system: [ 238.312762][ T955] 4 locks held by kworker/u4:1/21: [ 238.317872][ T955] #0: ffff8880a7cadd28 ((wq_completion)writeback){+.+.}, at: process_one_work+0x88b/0x1740 [ 238.328009][ T955] #1: ffff8880a9a07dc0 ((work_completion)(&(&wb->dwork)->work)){+.+.}, at: process_one_work+0x8c1/0x1740 [ 238.339514][ T955] #2: ffff88821597a0d8 (&type->s_umount_key#32){++++}, at: trylock_super+0x22/0x110 [ 238.349196][ T955] #3: ffff88821597c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 238.359792][ T955] 1 lock held by khungtaskd/955: [ 238.364915][ T955] #0: ffffffff88faba80 (rcu_read_lock){....}, at: debug_show_all_locks+0x5f/0x279 [ 238.374396][ T955] 1 lock held by khugepaged/961: [ 238.379320][ T955] #0: ffff88821597c990 (&sbi->s_journal_flag_rwsem){.+.+}, at: do_writepages+0xfa/0x2a0 [ 238.389246][ T955] 2 locks held by rsyslogd/8601: [ 238.394231][ T955] #0: ffff8880a3e18de0 (&f->f_pos_lock){+.+.}, at: __fdget_pos+0xee/0x110 [ 238.402871][ T955] #1: ffff8880ae826dd8 (hrtimer_bases.lock){-.-.}, at: try_to_wake_up+0xb0/0x1ab0 [ 238.412184][ T955] 2 locks held by getty/8691: [ 238.416916][ T955] #0: ffff888095c27090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.425916][ T955] #1: ffffc90005efd2e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.435626][ T955] 2 locks held by getty/8692: [ 238.440300][ T955] #0: ffff8880a08ee090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.449307][ T955] #1: ffffc90005f152e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.458957][ T955] 2 locks held by getty/8693: [ 238.463683][ T955] #0: ffff88809c8b7090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.472702][ T955] #1: ffffc90005f252e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.483077][ T955] 2 locks held by getty/8694: [ 238.489429][ T955] #0: ffff888093017090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.498437][ T955] #1: ffffc90005f212e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.508057][ T955] 2 locks held by getty/8695: [ 238.512786][ T955] #0: ffff88809a37a090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.521878][ T955] #1: ffffc90005f012e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.531754][ T955] 2 locks held by getty/8696: [ 238.536491][ T955] #0: ffff88808d9b7090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.545524][ T955] #1: ffffc90005f292e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.555269][ T955] 2 locks held by getty/8697: [ 238.560031][ T955] #0: ffff888098664090 (&tty->ldisc_sem){++++}, at: ldsem_down_read+0x33/0x40 [ 238.569068][ T955] #1: ffffc90005ef12e0 (&ldata->atomic_read_lock){+.+.}, at: n_tty_read+0x220/0x1bf0 [ 238.578946][ T955] 1 lock held by syz-execprog/8716: [ 238.584213][ T955] #0: ffff8880a31a8428 (&ei->i_mmap_sem){++++}, at: ext4_filemap_fault+0x7e/0xb2 [ 238.593501][ T955] [ 238.595847][ T955] ============================================= [ 238.595847][ T955] [ 238.604435][ T955] NMI backtrace for cpu 1 [ 238.608775][ T955] CPU: 1 PID: 955 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 238.617284][ T955] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 238.627341][ T955] Call Trace: [ 238.630650][ T955] dump_stack+0x172/0x1f0 [ 238.634987][ T955] nmi_cpu_backtrace.cold+0x70/0xb2 [ 238.640196][ T955] ? vprintk_func+0x86/0x189 [ 238.644865][ T955] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 238.650537][ T955] nmi_trigger_cpumask_backtrace+0x23b/0x28b [ 238.656551][ T955] arch_trigger_cpumask_backtrace+0x14/0x20 [ 238.662463][ T955] watchdog+0xc8f/0x1350 [ 238.666730][ T955] kthread+0x361/0x430 [ 238.670911][ T955] ? reset_hung_task_detector+0x30/0x30 [ 238.676451][ T955] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 238.682172][ T955] ret_from_fork+0x24/0x30 [ 238.686699][ T955] Sending NMI from CPU 1 to CPUs 0: [ 238.691970][ C0] NMI backtrace for cpu 0 skipped: idling at native_safe_halt+0xe/0x10 [ 238.693709][ T955] Kernel panic - not syncing: hung_task: blocked tasks [ 238.707066][ T955] CPU: 1 PID: 955 Comm: khungtaskd Not tainted 5.4.0-rc4-next-20191025 #0 [ 238.715685][ T955] Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 01/01/2011 [ 238.725735][ T955] Call Trace: [ 238.729025][ T955] dump_stack+0x172/0x1f0 [ 238.733347][ T955] panic+0x2e3/0x75c [ 238.737272][ T955] ? add_taint.cold+0x16/0x16 [ 238.741948][ T955] ? lapic_can_unplug_cpu.cold+0x3a/0x3a [ 238.747576][ T955] ? ___preempt_schedule+0x16/0x18 [ 238.752696][ T955] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 238.758954][ T955] ? nmi_trigger_cpumask_backtrace+0x24c/0x28b [ 238.765150][ T955] ? nmi_trigger_cpumask_backtrace+0x256/0x28b [ 238.771516][ T955] ? nmi_trigger_cpumask_backtrace+0x21b/0x28b [ 238.777687][ T955] watchdog+0xca0/0x1350 [ 238.781945][ T955] kthread+0x361/0x430 [ 238.786003][ T955] ? reset_hung_task_detector+0x30/0x30 [ 238.791553][ T955] ? kthread_mod_delayed_work+0x1f0/0x1f0 [ 238.797268][ T955] ret_from_fork+0x24/0x30 [ 238.805132][ T955] Kernel Offset: disabled [ 238.809469][ T955] Rebooting in 86400 seconds..