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From: Christoph Lameter <cl@linux.com>
To: David Rientjes <rientjes@google.com>
Cc: Thomas Garnier <thgarnie@google.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Greg Thelen <gthelen@google.com>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v2] memcg: Prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB
Date: Thu, 3 Nov 2016 15:33:27 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1611031531380.13315@east.gentwo.org> (raw)
In-Reply-To: <alpine.DEB.2.10.1611021744150.110015@chino.kir.corp.google.com>

On Wed, 2 Nov 2016, David Rientjes wrote:

> > Christoph on the first version advised removing invalid flags on the
> > caller and checking they are correct in kmem_cache_create. The memcg
> > path putting the wrong flags is through create_cache but I still used
> > this approach.
> >
>
> I think this is a rather trivial point since it doesn't matter if we clear
> invalid flags on the caller or in the callee and obviously
> kmem_cache_create() does it in the callee.

In order to be correct we need to do the following:

kmem_cache_create should check for invalid flags (and that includes
internal alloocator flgs) being set and refuse to create the slab cache.

memcg needs to call kmem_cache_create without any internal flags.

I also want to make sure that there are no other callers that specify
extraneou flags while we are at it.

WARNING: multiple messages have this Message-ID (diff)
From: Christoph Lameter <cl@linux.com>
To: David Rientjes <rientjes@google.com>
Cc: Thomas Garnier <thgarnie@google.com>,
	Pekka Enberg <penberg@kernel.org>,
	Joonsoo Kim <iamjoonsoo.kim@lge.com>,
	Andrew Morton <akpm@linux-foundation.org>,
	Linux-MM <linux-mm@kvack.org>,
	LKML <linux-kernel@vger.kernel.org>,
	Greg Thelen <gthelen@google.com>,
	Vladimir Davydov <vdavydov.dev@gmail.com>,
	Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH v2] memcg: Prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB
Date: Thu, 3 Nov 2016 15:33:27 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1611031531380.13315@east.gentwo.org> (raw)
In-Reply-To: <alpine.DEB.2.10.1611021744150.110015@chino.kir.corp.google.com>

On Wed, 2 Nov 2016, David Rientjes wrote:

> > Christoph on the first version advised removing invalid flags on the
> > caller and checking they are correct in kmem_cache_create. The memcg
> > path putting the wrong flags is through create_cache but I still used
> > this approach.
> >
>
> I think this is a rather trivial point since it doesn't matter if we clear
> invalid flags on the caller or in the callee and obviously
> kmem_cache_create() does it in the callee.

In order to be correct we need to do the following:

kmem_cache_create should check for invalid flags (and that includes
internal alloocator flgs) being set and refuse to create the slab cache.

memcg needs to call kmem_cache_create without any internal flags.

I also want to make sure that there are no other callers that specify
extraneou flags while we are at it.

--
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  reply	other threads:[~2016-11-03 20:33 UTC|newest]

Thread overview: 16+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-10-31 18:36 [PATCH v2] memcg: Prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB Thomas Garnier
2016-10-31 18:36 ` Thomas Garnier
2016-10-31 23:38 ` David Rientjes
2016-10-31 23:38   ` David Rientjes
2016-11-02 15:59   ` Thomas Garnier
2016-11-02 15:59     ` Thomas Garnier
2016-11-03  0:46     ` David Rientjes
2016-11-03  0:46       ` David Rientjes
2016-11-03 20:33       ` Christoph Lameter [this message]
2016-11-03 20:33         ` Christoph Lameter
2016-11-07 18:52         ` Thomas Garnier
2016-11-07 18:52           ` Thomas Garnier
2016-11-07 19:28           ` Christoph Lameter
2016-11-07 19:28             ` Christoph Lameter
2016-11-07 19:52             ` Thomas Garnier
2016-11-07 19:52               ` Thomas Garnier

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