From: Andrew Morton <akpm@linux-foundation.org>
To: Glauber Costa <glommer@parallels.com>
Cc: linux-mm@kvack.org, Pekka Enberg <penberg@kernel.org>,
Christoph Lameter <cl@linux.com>,
David Rientjes <rientjes@google.com>,
devel@openvz.org, Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: [PATCH v5] slab: Ignore internal flags in cache creation
Date: Thu, 18 Oct 2012 15:42:03 -0700 [thread overview]
Message-ID: <20121018154203.4b3a1179.akpm@linux-foundation.org> (raw)
In-Reply-To: <1350473811-16264-1-git-send-email-glommer@parallels.com>
On Wed, 17 Oct 2012 15:36:51 +0400
Glauber Costa <glommer@parallels.com> wrote:
> Some flags are used internally by the allocators for management
> purposes. One example of that is the CFLGS_OFF_SLAB flag that slab uses
> to mark that the metadata for that cache is stored outside of the slab.
>
> No cache should ever pass those as a creation flags. We can just ignore
> this bit if it happens to be passed (such as when duplicating a cache in
> the kmem memcg patches).
I may be minunderstanding this, but...
If some caller to kmem_cache_create() is passing in bogus flags then
that's a bug, and it is undesirable to hide such a bug in this fashion?
> Because such flags can vary from allocator to allocator, we allow them
> to make their own decisions on that, defining SLAB_AVAILABLE_FLAGS with
> all flags that are valid at creation time. Allocators that doesn't have
> any specific flag requirement should define that to mean all flags.
>
> Common code will mask out all flags not belonging to that set.
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next prev parent reply other threads:[~2012-10-18 22:42 UTC|newest]
Thread overview: 5+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-10-17 11:36 [PATCH v5] slab: Ignore internal flags in cache creation Glauber Costa
2012-10-17 21:07 ` David Rientjes
2012-10-31 7:13 ` Pekka Enberg
2012-10-18 22:42 ` Andrew Morton [this message]
2012-10-19 9:32 ` Glauber Costa
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