Hi all,

So I'd just like to give this a prod. I'm still getting DomU's randomly
go to 100% CPU usage using kernel 4.4.6 now. It seems running 4.4.6 as
the DomU does not induce these problems.

Latest crash message from today:
INFO: rcu_sched self-detected stall on CPU
        0-...: (20869552 ticks this GP) idle=9c9/140000000000001/0
softirq=1440865/1440865 fqs=15068
         (t=20874993 jiffies g=1354899 c=1354898 q=798)
rcu_sched kthread starved for 20829030 jiffies! g1354899 c1354898 f0x0
s3 ->state=0x0
Task dump for CPU 0:
kworker/u4:1    R  running task        0  5853      2 0x00000088
Workqueue: writeback wb_workfn (flush-202:0)
 ffffffff818d0c00 ffff88007fc03c58 ffffffff810a625f 0000000000000000
 ffffffff818d0c00 ffff88007fc03c70 ffffffff810a8699 0000000000000001
 ffff88007fc03ca0 ffffffff810d0e5a ffff88007fc170c0 ffffffff818d0c00
Call Trace:
 <IRQ>  [<ffffffff810a625f>] sched_show_task+0xaf/0x110
 [<ffffffff810a8699>] dump_cpu_task+0x39/0x40
 [<ffffffff810d0e5a>] rcu_dump_cpu_stacks+0x8a/0xc0
 [<ffffffff810d4884>] rcu_check_callbacks+0x424/0x7a0
 [<ffffffff810a91e1>] ? account_system_time+0x81/0x110
 [<ffffffff810a9481>] ? account_process_tick+0x61/0x160
 [<ffffffff810e8050>] ? tick_sched_do_timer+0x30/0x30
 [<ffffffff810d9749>] update_process_times+0x39/0x60
 [<ffffffff810e7aa6>] tick_sched_handle.isra.15+0x36/0x50
 [<ffffffff810e808d>] tick_sched_timer+0x3d/0x70
 [<ffffffff810da342>] __hrtimer_run_queues+0xf2/0x250
 [<ffffffff810da698>] hrtimer_interrupt+0xa8/0x190
 [<ffffffff8100c61e>] xen_timer_interrupt+0x2e/0x140
 [<ffffffff810c8555>] handle_irq_event_percpu+0x55/0x1e0
 [<ffffffff810cbbca>] handle_percpu_irq+0x3a/0x50
 [<ffffffff810c7d22>] generic_handle_irq+0x22/0x30
 [<ffffffff813e50ff>] __evtchn_fifo_handle_events+0x15f/0x180
 [<ffffffff813e5130>] evtchn_fifo_handle_events+0x10/0x20
 [<ffffffff813e2233>] __xen_evtchn_do_upcall+0x43/0x80
 [<ffffffff813e3ea0>] xen_evtchn_do_upcall+0x30/0x50
 [<ffffffff8165deb2>] xen_hvm_callback_vector+0x82/0x90
 <EOI>  [<ffffffff810b9ce2>] ? queued_spin_lock_slowpath+0x22/0x170
 [<ffffffff8165bc70>] _raw_spin_lock+0x20/0x30
 [<ffffffff811f1f34>] writeback_sb_inodes+0x124/0x560
 [<ffffffff8165ba36>] ? _raw_spin_unlock_irqrestore+0x16/0x20
 [<ffffffff811f23f6>] __writeback_inodes_wb+0x86/0xc0
 [<ffffffff811f2606>] wb_writeback+0x1d6/0x2d0
 [<ffffffff811f2e94>] wb_workfn+0x284/0x3e0
 [<ffffffff81093831>] process_one_work+0x151/0x400
 [<ffffffff8109437a>] worker_thread+0x11a/0x460
 [<ffffffff8165848f>] ? __schedule+0x2bf/0x880
 [<ffffffff81094260>] ? rescuer_thread+0x2f0/0x2f0
 [<ffffffff810993d9>] kthread+0xc9/0xe0
 [<ffffffff81099310>] ? kthread_park+0x60/0x60
 [<ffffffff8165c38f>] ret_from_fork+0x3f/0x70
 [<ffffffff81099310>] ? kthread_park+0x60/0x60

This repeats over and over causing 100% CPU usage - eventually on all
vcpus assigned to the DomU and the only recovery is 'xl destroy'.

I'm currently running Xen 4.6.1 on this system - with kernel 4.4.6 in
both the DomU and Dom0.

On 17/03/2016 8:39 AM, Steven Haigh wrote:
> Hi all,
> 
> I've noticed the following problem that ends up with a non-repsonsive PV
> DomU using kernel 4.4.5 under heavy disk IO:
> 
> INFO: rcu_sched self-detected stall on CPU
>         0-...: (6759098 ticks this GP) idle=cb3/140000000000001/0
> softirq=3244615/3244615 fqs=4
>          (t=6762321 jiffies g=2275626 c=2275625 q=54)
> rcu_sched kthread starved for 6762309 jiffies! g2275626 c2275625 f0x0 s3
> ->state=0x0
> Task dump for CPU 0:
> updatedb        R  running task        0  6027   6021 0x00000088
>  ffffffff818d0c00 ffff88007fc03c58 ffffffff810a625f 0000000000000000
>  ffffffff818d0c00 ffff88007fc03c70 ffffffff810a8699 0000000000000001
>  ffff88007fc03ca0 ffffffff810d0e5a ffff88007fc170c0 ffffffff818d0c00
> Call Trace:
>  <IRQ>  [<ffffffff810a625f>] sched_show_task+0xaf/0x110
>  [<ffffffff810a8699>] dump_cpu_task+0x39/0x40
>  [<ffffffff810d0e5a>] rcu_dump_cpu_stacks+0x8a/0xc0
>  [<ffffffff810d4884>] rcu_check_callbacks+0x424/0x7a0
>  [<ffffffff810a91e1>] ? account_system_time+0x81/0x110
>  [<ffffffff810a9481>] ? account_process_tick+0x61/0x160
>  [<ffffffff810e8050>] ? tick_sched_do_timer+0x30/0x30
>  [<ffffffff810d9749>] update_process_times+0x39/0x60
>  [<ffffffff810e7aa6>] tick_sched_handle.isra.15+0x36/0x50
>  [<ffffffff810e808d>] tick_sched_timer+0x3d/0x70
>  [<ffffffff810da342>] __hrtimer_run_queues+0xf2/0x250
>  [<ffffffff810da698>] hrtimer_interrupt+0xa8/0x190
>  [<ffffffff8100c61e>] xen_timer_interrupt+0x2e/0x140
>  [<ffffffff810c8555>] handle_irq_event_percpu+0x55/0x1e0
>  [<ffffffff810cbbca>] handle_percpu_irq+0x3a/0x50
>  [<ffffffff810c7d22>] generic_handle_irq+0x22/0x30
>  [<ffffffff813e51af>] __evtchn_fifo_handle_events+0x15f/0x180
>  [<ffffffff813e51e0>] evtchn_fifo_handle_events+0x10/0x20
>  [<ffffffff813e22e3>] __xen_evtchn_do_upcall+0x43/0x80
>  [<ffffffff813e3f50>] xen_evtchn_do_upcall+0x30/0x50
>  [<ffffffff8165def2>] xen_hvm_callback_vector+0x82/0x90
>  <EOI>  [<ffffffff810b9cd0>] ? queued_spin_lock_slowpath+0x10/0x170
>  [<ffffffff8165bcc0>] _raw_spin_lock+0x20/0x30
>  [<ffffffff811df221>] find_inode_fast+0x61/0xa0
>  [<ffffffff811df7ce>] iget_locked+0x6e/0x170
>  [<ffffffff81249203>] ext4_iget+0x33/0xae0
>  [<ffffffff81658f02>] ? out_of_line_wait_on_bit+0x72/0x80
>  [<ffffffff81249ce0>] ext4_iget_normal+0x30/0x40
>  [<ffffffff81253415>] ext4_lookup+0xd5/0x140
>  [<ffffffff811ceffd>] lookup_real+0x1d/0x50
>  [<ffffffff811cf3b3>] __lookup_hash+0x33/0x40
>  [<ffffffff811d1af7>] walk_component+0x177/0x280
>  [<ffffffff811d2c50>] path_lookupat+0x60/0x110
>  [<ffffffff811d47dc>] filename_lookup+0x9c/0x150
>  [<ffffffff811a982d>] ? kfree+0x10d/0x290
>  [<ffffffff8124122c>] ? call_filldir+0x9c/0x130
>  [<ffffffff811d441f>] ? getname_flags+0x4f/0x1f0
>  [<ffffffff811d4946>] user_path_at_empty+0x36/0x40
>  [<ffffffff811ca6f3>] vfs_fstatat+0x53/0xa0
>  [<ffffffff811c7919>] ? __fput+0x169/0x1d0
>  [<ffffffff811cab42>] SYSC_newlstat+0x22/0x40
>  [<ffffffff8110cad0>] ? __audit_syscall_exit+0x1f0/0x270
>  [<ffffffff81078115>] ? syscall_slow_exit_work+0x3f/0xc0
>  [<ffffffff8110c88f>] ? __audit_syscall_entry+0xaf/0x100
>  [<ffffffff811cad4e>] SyS_newlstat+0xe/0x10
>  [<ffffffff8165c06e>] entry_SYSCALL_64_fastpath+0x12/0x71
> 
> This ends up with the system not responding at 100% CPU usage.
> 
> Has anyone else seen this using kernel 4.4.5 in a DomU?
> 
> 
> 
> _______________________________________________
> Xen-devel mailing list
> Xen-devel@lists.xen.org
> http://lists.xen.org/xen-devel
> 

-- 
Steven Haigh

Email: netwiz@crc.id.au
Web: https://www.crc.id.au
Phone: (03) 9001 6090 - 0412 935 897