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Date: Mon, 7 Nov 2016 11:52:46 -0800 From: Thomas Garnier <thgarnie@...gle.com> To: Christoph Lameter <cl@...ux.com> Cc: David Rientjes <rientjes@...gle.com>, Pekka Enberg <penberg@...nel.org>, Joonsoo Kim <iamjoonsoo.kim@....com>, Andrew Morton <akpm@...ux-foundation.org>, Linux-MM <linux-mm@...ck.org>, LKML <linux-kernel@...r.kernel.org>, Greg Thelen <gthelen@...gle.com>, Vladimir Davydov <vdavydov.dev@...il.com>, Michal Hocko <mhocko@...nel.org> Subject: Re: [PATCH v2] memcg: Prevent memcg caches to be both OFF_SLAB & OBJFREELIST_SLAB On Mon, Nov 7, 2016 at 11:28 AM, Christoph Lameter <cl@...ux.com> wrote: > On Mon, 7 Nov 2016, Thomas Garnier wrote: > >> I am not sure that is possible. kmem_cache_create currently check for >> possible alias, I assume that it goes against what memcg tries to do. > > What does aliasing have to do with this? The aliases must have the same > flags otherwise the caches would not have been merged. > I assume there might be cases where the parent cache and the new memcg cache are compatible for merge (same flags and size). We can bypass that by adding SLAB_NEVER_MERGE but I am not sure what is the consequence of that. >> Separate the changes in two patches might make sense: >> >> 1) Fix the original bug by masking the flags passed to create_cache >> 2) Add flags check in kmem_cache_create. >> >> Does it make sense? > > Sure. > Great, I will send both patches. >> > I also want to make sure that there are no other callers that specify >> > extraneou flags while we are at it. >> I will review as many as I can but we might run into surprises (quick >> boot on defconfig didn't show anything). That's why having two >> different patches might be useful. > > These surprises can be caught later ... Just make sure that the core works > fine with this. You cannot audit all drivers. > Okay, I will. -- Thomas
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