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SubjectRe: kswapd craziness round 2
From
On Mon, Feb 18, 2013 at 2:18 PM, Daniel J Blueman
<daniel@numascale-asia.com> wrote:
> On Monday, 18 February 2013 06:10:02 UTC+8, Jiri Slaby wrote:
>
>> Hi,
>>
>> You still feel the sour taste of the "kswapd craziness in v3.7" thread,
>> right? Welcome to the hell, part two :{.
>>
>> I believe this started happening after update from
>> 3.8.0-rc4-next-20130125 to 3.8.0-rc7-next-20130211. The same as before,
>> many hours of uptime are needed and perhaps some suspend/resume cycles
>> too. Memory pressure is not high, plenty of I/O cache:
>> # free
>> total used free shared buffers cached
>> Mem: 6026692 5571184 455508 0 351252 2016648
>> -/+ buffers/cache: 3203284 2823408
>> Swap: 0 0 0
>>
>> kswap is working very toughly though:
>> root 580 0.6 0.0 0 0 ? S úno12 46:21 [kswapd0]
>>
>> This happens on I/O activity right now. For example by updatedb or find
>> /. This is what the stack trace of kswapd0 looks like:
>> [<ffffffff8113c431>] shrink_slab+0xa1/0x2d0
>> [<ffffffff8113ecd1>] kswapd+0x541/0x930
>> [<ffffffff810a3000>] kthread+0xc0/0xd0
>> [<ffffffff816beb5c>] ret_from_fork+0x7c/0xb0
>> [<ffffffffffffffff>] 0xffffffffffffffff
>
> Likewise with 3.8-rc, I've been able to reproduce [1] a livelock scenario
> which hoses the box and observe RCU stalls are observed [2].
>
> There may be a connection; I'll do a bit more debugging in the next few
> days.
>
> Daniel
>
> --- [1]
>
> 1. live-booted image using ramdisk
> 2. boot 3.8-rc with <16GB memory and without swap
> 3. run OpenMP NAS Parallel Benchmark dc.B against local disk (ie not
> ramdisk)
> 4. observe hang O(30) mins later
>
> --- [2]
>
> [ 2675.587878] INFO: rcu_sched self-detected stall on CPU { 5} (t=24000
> jiffies g=6313 c=6312 q=68)

Does Ingo's revert help? https://lkml.org/lkml/2013/2/15/168
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