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

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Message-ID: <tnx630ibd2q.fsf@e102109-lin.cambridge.arm.com>
Date:	Wed, 14 Jul 2010 10:57:33 +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

Zeno Davatz <zdavatz@...il.com> wrote:
> I got a new Intel core-8 i7 processor.
>
> I am on kernel uname -a
>
> Linux zenogentoo 2.6.35-rc5 #97 SMP Tue Jul 13 16:13:25 CEST 2010 i686
> Intel(R) Core(TM) i7 CPU 960 @ 3.20GHz GenuineIntel GNU/Linux
>
> 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.
>
> dmesg tell me that
>
> kmemleak: 38 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> kmemleak: 2 new suspected memory leaks (see /sys/kernel/debug/kmemleak)
> kmemleak: 1 new suspected memory leaks (see /sys/kernel/debug/kmemleak)

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%.

-- 
Catalin
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