linux-kernel - Re: Why kmem_cache_free occupy CPU for more than 10 seconds?

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Message-ID: <ac8af0be0704110253p74de6197p1df6a5b99585709c@mail.gmail.com>
Date:	Wed, 11 Apr 2007 17:53:49 +0800
From:	"Zhao Forrest" <forrest.zhao@...il.com>
To:	"Pekka Enberg" <penberg@...helsinki.fi>
Cc:	linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: Re: Why kmem_cache_free occupy CPU for more than 10 seconds?

I got some new information:
Before soft lockup message is out, we have:
[root@...sh-dhcp-149 home]# cat /proc/slabinfo |grep buffer_head
buffer_head       10927942 10942560    120   32    1 : tunables   32
16    8 : slabdata 341955 341955      6 : globalstat 37602996 11589379
1174373    6                              0    1 6918 12166031 1013708
: cpustat 35254590 2350698 13610965 907286

Then after buffer_head is freed, we have:
[root@...sh-dhcp-149 home]# cat /proc/slabinfo |grep buffer_head
buffer_head         9542  36384    120   32    1 : tunables   32   16
  8 : slabdata   1137   1137    245 : globalstat 37602996 11589379
1174373    6                                  0    1 6983 20507478
1708818 : cpustat 35254625 2350704 16027174 1068367

Does this huge number of buffer_head cause the soft lockup?

Thanks,
Forrest

On 4/11/07, Pekka Enberg <penberg@...helsinki.fi> wrote:
> On 4/11/07, Zhao Forrest <forrest.zhao@...il.com> wrote:
> > We're using RHEL5 with kernel version 2.6.18-8.el5.
> > When doing a stress test on raw device for about 3-4 hours, we found
> > the soft lockup message in dmesg.
> > I know we're not reporting the bug on the latest kernel, but does any
> > expert know if this is the known issue in old kernel? Or why
> > kmem_cache_free occupy CPU for more than 10 seconds?
>
> Sounds like slab corruption. CONFIG_DEBUG_SLAB should tell you more.
>
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