linux-kernel - Re: [PATCH v3 2/5] kmemleak: add clear command support

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Message-ID: <43e72e890909080916j159c5fadgda3f2c87aa3b965@mail.gmail.com>
Date:	Tue, 8 Sep 2009 09:16:56 -0700
From:	"Luis R. Rodriguez" <lrodriguez@...eros.com>
To:	Catalin Marinas <catalin.marinas@....com>
Cc:	linux-kernel@...r.kernel.org, linux-mm@...ck.org,
	penberg@...helsinki.fi
Subject: Re: [PATCH v3 2/5] kmemleak: add clear command support

On Tue, Sep 8, 2009 at 9:11 AM, Catalin Marinas<catalin.marinas@....com> wrote:
> On Fri, 2009-09-04 at 17:44 -0700, Luis R. Rodriguez wrote:
>>  /*
>> + * We use grey instead of black to ensure we can do future
>> + * scans on the same objects. If we did not do future scans
>> + * these black objects could potentially contain references to
>> + * newly allocated objects in the future and we'd end up with
>> + * false positives.
>> + */
>> +static void kmemleak_clear(void)
>> +{
>> +     struct kmemleak_object *object;
>> +     unsigned long flags;
>> +
>> +     stop_scan_thread();
>> +
>> +     rcu_read_lock();
>> +     list_for_each_entry_rcu(object, &object_list, object_list) {
>> +             spin_lock_irqsave(&object->lock, flags);
>> +             if ((object->flags & OBJECT_REPORTED) &&
>> +                 unreferenced_object(object))
>> +                     object->min_count = -1;
>> +             spin_unlock_irqrestore(&object->lock, flags);
>> +     }
>> +     rcu_read_unlock();
>> +
>> +     start_scan_thread();
>> +}
>
> Do we need to stop and start the scanning thread here? When starting it,
> it will trigger a memory scan automatically. I don't think we want this
> as a side-effect, so I dropped these lines from your patch.

OK thanks.

> Also you set min_count to -1 here which means black object, so a
> subsequent patch corrects it. I'll set min_count to 0 here in case
> anyone bisects over it.

Dah, thanks for catching that, seems I only fixed the named set.

  Luis
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