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Date: Mon, 2 Sep 2013 16:48:40 +0100
From: Catalin Marinas <catalin.marinas@arm.com>
To: Max Filippov <jcmvbkbc@gmail.com>
Cc: Martin =?utf-8?Q?MOKREJ=C5=A0?= <mmokrejs@gmail.com>,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: 3.10.9: kmemleak disables all CPUs except CPU0
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On Mon, Sep 02, 2013 at 04:44:52PM +0100, Max Filippov wrote:
> On Mon, Sep 2, 2013 at 7:31 PM, Catalin Marinas <catalin.marinas@arm.com> wrote:
> > On 31 August 2013 14:35, Martin MOKREJŠ <mmokrejs@gmail.com> wrote:
> >>   never realized that my CPUs are gone if I compile into kernel kmemleak.
> >> Is that really the aim?
> >>
> >> CONFIG_HAVE_DEBUG_KMEMLEAK=y
> >> CONFIG_DEBUG_KMEMLEAK=y
> >> CONFIG_DEBUG_KMEMLEAK_EARLY_LOG_SIZE=400
> >> # CONFIG_DEBUG_KMEMLEAK_TEST is not set
> >> # CONFIG_DEBUG_KMEMLEAK_DEFAULT_OFF is not set
> >>
> >> 1.  Why isn't there /sys/devices/system/cpu/cpu0/online file?
> >> Does not matter if it contains 0 or 1. It just should exist.
> >
> > I can't really see how kmemleak would do this, maybe other config
> > options that get set/cleared in the process of selecting kmemleak. Can
> 
> Seems to be kmemcheck: from arch/x86/mm/kmemcheck/kmemcheck.c:
> 
> int __init kmemcheck_init(void)
> {
> #ifdef CONFIG_SMP
>         /*
>          * Limit SMP to use a single CPU. We rely on the fact that this code
>          * runs before SMP is set up.
>          */
>         if (setup_max_cpus > 1) {
>                 printk(KERN_INFO
>                         "kmemcheck: Limiting number of CPUs to 1.\n");
>                 setup_max_cpus = 1;
>         }
> #endif

Ah, ok, not my problem then ;)

-- 
Catalin