Re: 3.10.9: kmemleak disables all CPUs except CPU0

[Max Filippov]

On Mon, Sep 2, 2013 at 7:31 PM, Catalin Marinas <catalin.marinas@xxxxxxx> wrote:
> On 31 August 2013 14:35, Martin MOKREJÅ <mmokrejs@xxxxxxxxx> 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

-- 
Thanks.
-- Max
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