linux-kernel - Re: kmemleak, cpu usage jump out of nowhere

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Date:	Wed, 14 Jul 2010 12:54:03 +0100
From:	Catalin Marinas <catalin.marinas@....com>
To:	Zeno Davatz <zdavatz@...il.com>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: kmemleak, cpu usage jump out of nowhere

On Wed, 2010-07-14 at 11:04 +0100, Zeno Davatz wrote:
> On Wed, Jul 14, 2010 at 11:57 AM, Catalin Marinas
> <catalin.marinas@....com> wrote:
> > Zeno Davatz <zdavatz@...il.com> wrote:
> >> Sometimes in the middle of nowhere all of a sudden all of my 8-cores
> >> are at 100% CPU usage and my machine really lags and hangs and is not
> >> useable anymore. Some random process just grabs a bunch CPUs according
> >> to htop.
> >
> > These may be related to the NO_BOOTMEM configuration (I sent a patch in
> > a separate reply).
> >
> > But even when kmemleak scans the memory, it only uses a single thread
> > and you should only see a single CPU going to 100%. I don't think
> > kmemleak scanning can explain why all the 8 cores are going up to 100%.
> 
> I am doing:
> 
> /usr/src/my2.6> sudo patch -p1 < patch_catalin
> patching file mm/bootmem.c
> Hunk #1 FAILED at 435.
> Hunk #2 FAILED at 461.
> 2 out of 2 hunks FAILED -- saving rejects to file mm/bootmem.c.rej
> patching file mm/page_alloc.c
> Hunk #1 FAILED at 3659.
> 1 out of 1 hunk FAILED -- saving rejects to file mm/page_alloc.c.rej
> 
> Any hints why it wont apply? Will this patch be in the next RC?

The patch is against 2.6.35-rc4. I'll send it to Linus and hopefully it
will get merged during rc.

BTW, you can disable kmemleak scanning by doing:

# echo scan=off > /sys/kernel/debug/kmemleak

Do you still get that high CPU usage?

-- 
Catalin

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