linux-kernel - Re: [PATCH v4 1/2] timers: Don't wake ktimersoftd on every tick

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Message-ID: <b4691b85-2346-36ac-3270-ff722032ea1a@ni.com>
Date:   Wed, 20 Jun 2018 09:24:43 -0500
From:   Haris Okanovic <haris.okanovic@...com>
To:     Daniel Bristot de Oliveira <daniel@...stot.me>
Cc:     Mike Galbraith <efault@....de>, linux-rt-users@...r.kernel.org,
        linux-kernel@...r.kernel.org
Subject: Re: [PATCH v4 1/2] timers: Don't wake ktimersoftd on every tick

Hi Daniel,

I didn't have time to look at it yet, aside from confirming Mike's issue 
reproduces on my machine. It's still on my backlog to investigate.

-- Haris


On 06/19/2018 07:43 AM, Daniel Bristot de Oliveira wrote:
> 
> 
> On 04/12/2018 05:00 PM, Haris Okanovic wrote:
>> Hi Mike,
>>
>> I haven't tested the patch with wireshark until now. My system also
>> hangs shortly after it starts. I'm pretty sure I hit workqueues in my
>> earlier tests via the block driver, but it's clearly not whatever
>> wireshark is using. I'll look at it and try to post a fix. CCing the
>> list to avoid this patch until then.
> 
> Hi Haris,
> 
> Do we have any update regarding a newer version of this patch?
> 
> -- Daniel
> 
>> Thanks,
>> Haris
>>
>>
>> On 04/09/2018 11:02 PM, Mike Galbraith wrote:
>>> Hi,
>>>
>>> Are these patches dead, or are you planning another submission?  I ask
>>> because I discovered that with them applied, firing up wireshark hangs
>>> the box 100% repeatably, with wireshark never fully initializing.
>>>
>>> Applying them to an otherwise virgin 4.14.20-rt17 to be sure...
>>>
>>> crash> bt 6016PID: 6016   TASK: ffff95dd68572180  CPU: 2   COMMAND:
>>> "dumpcap"
>>>    #0 [ffffb490094f3bc0] __schedule at ffffffffa56d55b9
>>>    #1 [ffffb490094f3c40] schedule at ffffffffa56d5a03
>>>    #2 [ffffb490094f3c58] schedule_timeout at ffffffffa56d8467
>>>    #3 [ffffb490094f3cd8] wait_for_completion at ffffffffa56d6e34
>>>    #4 [ffffb490094f3d18] __wait_rcu_gp at ffffffffa50e59cd
>>>    #5 [ffffb490094f3d58] synchronize_rcu at ffffffffa50ec14e
>>>    #6 [ffffb490094f3d98] packet_set_ring at ffffffffc0c74da0 [af_packet]
>>>    #7 [ffffb490094f3e50] packet_setsockopt at ffffffffc0c75d23 [af_packet]
>>>    #8 [ffffb490094f3ef8] sys_setsockopt at ffffffffa558a5e2
>>>    #9 [ffffb490094f3f30] do_syscall_64 at ffffffffa5001b05
>>> #10 [ffffb490094f3f50] entry_SYSCALL_64_after_hwframe at ffffffffa5800065
>>>       RIP: 00007f3107a1cfaa  RSP: 00007ffc9745c2e8  RFLAGS: 00000246
>>>       RAX: ffffffffffffffda  RBX: 0000000000000001  RCX: 00007f3107a1cfaa
>>>       RDX: 0000000000000005  RSI: 0000000000000107  RDI: 0000000000000003
>>>       RBP: 000055ae1d8eb470   R8: 000000000000001c   R9: 0000000000000002
>>>       R10: 00007ffc9745c350  R11: 0000000000000246  R12: 00007ffc9745c350
>>>       R13: 0000000000000000  R14: 000055ae1d8eb200  R15: 000055ae1d8eb2d0
>>>       ORIG_RAX: 0000000000000036  CS: 0033  SS: 002b
>>> crash> dmesg
>>> ...
>>> [  483.808197] BUG: workqueue lockup - pool cpus=2 node=0 flags=0x0
>>> nice=0 stuck for 52s!
>>> [  483.808204] Showing busy workqueues and worker pools:
>>> [  483.808206] workqueue events: flags=0x0
>>> [  483.808208]   pwq 4: cpus=2 node=0 flags=0x0 nice=0 active=1/256
>>> [  483.808211]     pending: check_corruption
>>> [  492.695124] sysrq: SysRq : Trigger a crash
>>>
>> -- 
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