Re: [PATCH v5 06/14] memcg: kmem controller infrastructure

From: David Rientjes
Date: Thu Oct 18 2012 - 18:06:57 EST


On Thu, 18 Oct 2012, Glauber Costa wrote:

> > Do we actually need to test PF_KTHREAD when current->mm == NULL?
> > Perhaps because of aio threads whcih temporarily adopt a userspace mm?
>
> I believe so. I remember I discussed this in the past with David
> Rientjes and he advised me to test for both.
>

PF_KTHREAD can do use_mm() to assume an ->mm but hopefully they aren't
allocating slab while doing so. Have you considered actually charging
current->mm->owner for that memory, though, since the kthread will have
freed the memory before unuse_mm() or otherwise have charged it on behalf
of a user process, i.e. only exempting PF_KTHREAD?
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