[....] Starting enhanced syslogd: rsyslogd[?25l[?1c7[ ok 8[?25h[?0c. [ 45.928509][ T26] audit: type=1800 audit(1561232342.503:25): pid=8082 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="cron" dev="sda1" ino=2414 res=0 [ 45.949163][ T26] audit: type=1800 audit(1561232342.503:26): pid=8082 uid=0 auid=4294967295 ses=4294967295 subj=_ op=collect_data cause=failed(directio) comm="startpar" name="mcstrans" dev="sda1" ino=2457 res=0 [ 45.982610][ T26] audit: type=1800 audit(1561232342.513:27): pid=8082 uid=0 auid=4294967295 ses=4294967295 subj=_ 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 '10.128.0.241' (ECDSA) to the list of known hosts. executing program executing program syzkaller login: [ 1166.023129][ C1] rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: [ 1166.030179][ C1] (detected by 1, t=10502 jiffies, g=6221, q=39) [ 1166.036613][ C1] rcu: All QSes seen, last rcu_preempt kthread activity 10503 (4295053756-4295043253), jiffies_till_next_fqs=1, root ->qsmask 0x0 [ 1166.050067][ C1] syz-executor551 R running task 22976 8244 8242 0x00004000 [ 1166.057995][ C1] Call Trace: [ 1166.061294][ C1] [ 1166.064373][ C1] sched_show_task+0x3bd/0x490 [ 1166.069159][ C1] ? __ia32_sys_sched_rr_get_interval_time32+0xf0/0xf0 [ 1166.076089][ C1] ? find_next_bit+0x10c/0x120 [ 1166.080900][ C1] ? check_preemption_disabled+0x47/0x280 [ 1166.086679][ C1] rcu_sched_clock_irq+0x1607/0x1740 [ 1166.092028][ C1] update_process_times+0x134/0x190 [ 1166.097371][ C1] tick_sched_timer+0x257/0x410 [ 1166.102237][ C1] ? tick_setup_sched_timer+0x2b0/0x2b0 [ 1166.107793][ C1] __hrtimer_run_queues+0x471/0x8b0 [ 1166.113008][ C1] ? hrtimer_interrupt+0xda0/0xda0 [ 1166.118194][ C1] ? ktime_get_update_offsets_now+0x234/0x250 [ 1166.124288][ C1] hrtimer_interrupt+0x38c/0xda0 [ 1166.129329][ C1] ? rcu_read_lock_sched_held+0x127/0x1c0 [ 1166.135979][ C1] smp_apic_timer_interrupt+0xee/0x260 [ 1166.141448][ C1] apic_timer_interrupt+0xf/0x20 [ 1166.146386][ C1] [ 1166.149391][ C1] RIP: 0010:__find_get_block+0x235/0x1080 [ 1166.155119][ C1] Code: fc ff df 80 3c 08 00 74 0c 48 c7 c7 a0 63 aa 88 e8 a0 a6 e8 ff 48 83 3d 08 2f e4 06 00 0f 84 d9 0d 00 00 fb 66 0f 1f 44 00 00 <48> 85 db 74 50 e8 41 7d af ff 48 89 df e8 d9 d6 ff ff 49 89 de 48 [ 1166.174814][ C1] RSP: 0018:ffff888097faedd8 EFLAGS: 00000282 ORIG_RAX: ffffffffffffff13 [ 1166.183300][ C1] RAX: 1ffffffff1154c74 RBX: ffff88809137abd0 RCX: dffffc0000000000 [ 1166.191374][ C1] RDX: dffffc0000000000 RSI: ffff88808ee6ade8 RDI: ffff88808ee6ad68 [ 1166.199459][ C1] RBP: ffff888097faee38 R08: ffff88808ee6ad80 R09: ffffed101226f587 [ 1166.207788][ C1] R10: ffffed101226f587 R11: 1ffff1101226f586 R12: 0000000000031528 [ 1166.215767][ C1] R13: 0000000000000000 R14: 0000000000001000 R15: 0000000000000001 [ 1166.223774][ C1] ? __find_get_block+0x1f9/0x1080 [ 1166.228907][ C1] __getblk_gfp+0x30/0x9c0 [ 1166.233418][ C1] ? ext4_get_group_desc+0x24e/0x2a0 [ 1166.238785][ C1] __ext4_get_inode_loc+0x37b/0xcb0 [ 1166.245508][ C1] ext4_reserve_inode_write+0xe9/0x220 [ 1166.250989][ C1] ext4_mark_inode_dirty+0x102/0x790 [ 1166.256292][ C1] ? trace_ext4_evict_inode+0x290/0x290 [ 1166.261863][ C1] ? __ext4_journal_start_sb+0x286/0x300 [ 1166.267534][ C1] ext4_dirty_inode+0x8b/0xb0 [ 1166.272218][ C1] ? trace_ext4_mark_inode_dirty+0x290/0x290 [ 1166.278281][ C1] __mark_inode_dirty+0xbf/0x700 [ 1166.283313][ C1] ? unlock_page+0x162/0x1d0 [ 1166.287981][ C1] generic_write_end+0x151/0x320 [ 1166.292934][ C1] ext4_da_write_end+0x72e/0x8a0 [ 1166.297887][ C1] ? ext4_da_write_begin+0xcd0/0xcd0 [ 1166.303276][ C1] generic_perform_write+0x3ac/0x550 [ 1166.308579][ C1] ? grab_cache_page_write_begin+0xa0/0xa0 [ 1166.314452][ C1] ? file_remove_privs+0x600/0x600 [ 1166.319652][ C1] ? trace_lock_acquire+0x11c/0x190 [ 1166.324878][ C1] ? lock_acquire+0x158/0x250 [ 1166.329589][ C1] __generic_file_write_iter+0x24b/0x520 [ 1166.335239][ C1] ? generic_write_checks+0x3e5/0x480 [ 1166.340624][ C1] ext4_file_write_iter+0x902/0x12e0 [ 1166.345923][ C1] ? ext4_file_read_iter+0x370/0x370 [ 1166.351284][ C1] ? kasan_kmalloc+0x9/0x10 [ 1166.355795][ C1] ? __kmalloc+0x23c/0x310 [ 1166.360215][ C1] ? kmalloc_array+0x32/0x60 [ 1166.364813][ C1] ? iter_file_splice_write+0x220/0xf40 [ 1166.370362][ C1] ? direct_splice_actor+0xf7/0x130 [ 1166.375561][ C1] ? splice_direct_to_actor+0x4c6/0xb40 [ 1166.381284][ C1] ? do_splice_direct+0x279/0x3d0 [ 1166.386384][ C1] ? do_sendfile+0x8a3/0x1110 [ 1166.391595][ C1] ? __x64_sys_sendfile64+0x13b/0x220 [ 1166.396974][ C1] ? entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 1166.403139][ C1] ? trace_lock_acquire+0x190/0x190 [ 1166.408357][ C1] do_iter_readv_writev+0x6f5/0x9c0 [ 1166.413580][ C1] ? vfs_dedupe_file_range+0x9c0/0x9c0 [ 1166.419403][ C1] ? security_file_permission+0x148/0x350 [ 1166.425173][ C1] ? rw_verify_area+0x1c2/0x360 [ 1166.430045][ C1] do_iter_write+0x180/0x590 [ 1166.434646][ C1] ? rcu_read_lock_sched_held+0x127/0x1c0 [ 1166.440380][ C1] ? trace_kmalloc+0xcd/0x130 [ 1166.445110][ C1] ? splice_from_pipe_next+0xa2/0x440 [ 1166.450492][ C1] ? __kmalloc+0x254/0x310 [ 1166.454923][ C1] vfs_iter_write+0x7c/0xa0 [ 1166.459444][ C1] iter_file_splice_write+0x79f/0xf40 [ 1166.465877][ C1] ? atime_needs_update+0x2d9/0x570 [ 1166.471112][ C1] ? splice_from_pipe+0x200/0x200 [ 1166.476170][ C1] ? splice_from_pipe+0x200/0x200 [ 1166.481213][ C1] direct_splice_actor+0xf7/0x130 [ 1166.486250][ C1] splice_direct_to_actor+0x4c6/0xb40 [ 1166.491636][ C1] ? do_splice_direct+0x3d0/0x3d0 [ 1166.496669][ C1] ? pipe_to_sendpage+0x310/0x310 [ 1166.501708][ C1] ? rw_verify_area+0x1c2/0x360 [ 1166.506573][ C1] do_splice_direct+0x279/0x3d0 [ 1166.511452][ C1] ? splice_direct_to_actor+0xb40/0xb40 [ 1166.517020][ C1] ? rcu_read_lock_sched_held+0xc0/0x1c0 [ 1166.522667][ C1] ? rcu_sync_lockdep_assert+0x5e/0xa0 [ 1166.528136][ C1] ? __sb_start_write+0x199/0x360 [ 1166.533161][ C1] ? security_file_permission+0x148/0x350 [ 1166.538892][ C1] do_sendfile+0x8a3/0x1110 [ 1166.543417][ C1] ? compat_writev+0x3b0/0x3b0 [ 1166.548189][ C1] ? kasan_check_write+0x14/0x20 [ 1166.553480][ C1] ? _copy_from_user+0xe0/0x120 [ 1166.558345][ C1] __x64_sys_sendfile64+0x13b/0x220 [ 1166.563632][ C1] ? prepare_exit_to_usermode+0x1e1/0x4f0 [ 1166.569374][ C1] ? __ia32_sys_sendfile+0xb0/0xb0 [ 1166.574541][ C1] ? trace_irq_disable_rcuidle+0x23/0x1c0 [ 1166.580287][ C1] ? do_syscall_64+0x1d/0x140 [ 1166.585428][ C1] do_syscall_64+0xfe/0x140 [ 1166.589963][ C1] entry_SYSCALL_64_after_hwframe+0x49/0xbe [ 1166.595959][ C1] RIP: 0033:0x4417c9 [ 1166.599895][ C1] Code: e8 7c e7 ff ff 48 83 c4 18 c3 0f 1f 80 00 00 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 0f 83 bb 07 fc ff c3 66 2e 0f 1f 84 00 00 00 00 [ 1166.619516][ C1] RSP: 002b:00007ffda91c5b38 EFLAGS: 00000246 ORIG_RAX: 0000000000000028 [ 1166.627947][ C1] RAX: ffffffffffffffda RBX: 00007ffda91c5ce0 RCX: 00000000004417c9 [ 1166.635935][ C1] RDX: 0000000020000000 RSI: 0000000000000003 RDI: 0000000000000003 [ 1166.643928][ C1] RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000 [ 1166.651915][ C1] R10: 00008080fffffffe R11: 0000000000000246 R12: 0000000000000000 [ 1166.659906][ C1] R13: 00000000004024a0 R14: 0000000000000000 R15: 0000000000000000 [ 1166.668016][ C1] rcu: rcu_preempt kthread starved for 10566 jiffies! g6221 f0x2 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 [ 1166.679130][ C1] rcu: RCU grace-period kthread stack dump: [ 1166.685032][ C1] rcu_preempt R running task 26336 10 2 0x80004000 [ 1166.692954][ C1] Call Trace: [ 1166.696380][ C1] __schedule+0x658/0x9e0 [ 1166.700748][ C1] ? is_mmconf_reserved+0x410/0x410 [ 1166.706413][ C1] ? debug_object_init+0x20/0x20 [ 1166.711648][ C1] schedule+0x131/0x1d0 [ 1166.715912][ C1] schedule_timeout+0x19d/0x2b0 [ 1166.720867][ C1] ? console_conditional_schedule+0x40/0x40 [ 1166.726783][ C1] ? run_local_timers+0x120/0x120 [ 1166.732074][ C1] ? prepare_to_swait_exclusive+0x2a0/0x2a0 [ 1166.738039][ C1] rcu_gp_kthread+0xfd8/0x1880 [ 1166.742845][ C1] ? kasan_check_write+0x14/0x20 [ 1166.747806][ C1] ? rcu_report_qs_rsp+0x150/0x150 [ 1166.752934][ C1] ? _raw_spin_unlock_irqrestore+0x77/0xe0 [ 1166.758843][ C1] ? _raw_spin_unlock_irqrestore+0xbc/0xe0 [ 1166.764672][ C1] ? __kthread_parkme+0xfb/0x150 [ 1166.769626][ C1] kthread+0x325/0x350 [ 1166.773702][ C1] ? rcu_report_qs_rsp+0x150/0x150 [ 1166.778819][ C1] ? kthread_blkcg+0xe0/0xe0 [ 1166.783428][ C1] ret_from_fork+0x24/0x30