linux-kernel - Re: [PROBLEM] hard-lock with kmemtrace, relayfs, and splice

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Date:	Fri, 24 Oct 2008 12:44:48 +0800
From:	"Peter Teoh" <htmldeveloper@...il.com>
To:	"Pekka Enberg" <penberg@...helsinki.fi>,
	"Eduard - Gabriel Munteanu" <eduard.munteanu@...ux360.ro>
Cc:	zanussi@...cast.net, jens.axboe@...cle.com,
	linux-kernel@...r.kernel.org
Subject: Re: [PROBLEM] hard-lock with kmemtrace, relayfs, and splice

after doing a

git clone git://repo.or.cz/linux-2.6/kmemtrace.git

I reboot the OS and encountered several application crashes.....the
logs are as per attached....please comment.

for bug0 and bug1, the system go into a state of complete
non-responsive, even connecting via SSH into the system becomes
impossible, and bug0 and bug1 was generated just before it goes into
this state.

for bug2, the mouse seemed to respond, i managed to output the dmesg
(which is bug2 itself).

any comments?

On Fri, Oct 10, 2008 at 5:42 PM, Pekka Enberg <penberg@...helsinki.fi> wrote:
> (I'm cc'ing Tom, Jens, and LKML.)
>
> On Fri, 2008-10-10 at 12:10 +0300, Pekka Enberg wrote:
>> > I'm seeing a hard lock on my machine when I run kmemtraced with the
>> > following patch applied:
>> >
>> > http://git.kernel.org/?p=linux/kernel/git/penberg/slab-2.6.git;a=commitdiff;h=17ca1d5506b1db433f0b7167a627bfd55d319dd3
>> >
>> > I can enable/disable kmemtrace via the debugfs files fine and can also
>> > read the relay files with cat.
>> >
>> > Any idea where this is coming from?
>>
>> OK, it's the first splice() call in reader_thread() that causes the
>> hang. Hmm.
>
> To recap, with a CONFIG_KMEMTRACE enabled kernel from the
> "topic/kmemtrace" branch of:
>
>  git://git.kernel.org/pub/scm/linux/kernel/git/penberg/slab-2.6.git topic/kmemtrace
>
> running the "kmemtraced" program from
>
>  git://git.kernel.org/pub/scm/linux/kernel/git/penberg/kmemtrace-user.git
>
> results to a hard lock on my machine. I am unable to find anything
> obviously wrong with it and as I can read/write the relay files just
> fine, I'm beginning to think it's problem in relayfs splice
> implementation.
>
> Tom, thoughts?
>
>                Pekka
>
>
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-- 
Regards,
Peter Teoh

Download attachment "bug0" of type "application/octet-stream" (35275 bytes)

Download attachment "bug1" of type "application/octet-stream" (124817 bytes)

Download attachment "bug2" of type "application/octet-stream" (92479 bytes)