From: Matthew Wilcox <willy@infradead.org>
To: Christopher Lameter <cl@linux.com>
Cc: linux-mm@kvack.org, Matthew Wilcox <mawilcox@microsoft.com>,
Pekka Enberg <penberg@kernel.org>,
David Rientjes <rientjes@google.com>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Andrew Morton <akpm@linux-foundation.org>,
linux-kernel@vger.kernel.org, Jan Kara <jack@suse.cz>,
Jeff Layton <jlayton@redhat.com>,
Mel Gorman <mgorman@techsingularity.net>
Subject: Re: [PATCH v2 2/2] slab: __GFP_ZERO is incompatible with a constructor
Date: Wed, 11 Apr 2018 12:24:48 -0700 [thread overview]
Message-ID: <20180411192448.GD22494@bombadil.infradead.org> (raw)
In-Reply-To: <alpine.DEB.2.20.1804110842560.3788@nuc-kabylake>
On Wed, Apr 11, 2018 at 08:44:23AM -0500, Christopher Lameter wrote:
> > +++ b/mm/slub.c
> > @@ -2725,7 +2726,7 @@ static __always_inline void *slab_alloc_node(struct kmem_cache *s,
> > stat(s, ALLOC_FASTPATH);
> > }
> >
> > - if (unlikely(gfpflags & __GFP_ZERO) && object)
> > + if (unlikely(gfpflags & __GFP_ZERO) && object && slab_no_ctor(s))
> > memset(object, 0, s->object_size);
> >
> > slab_post_alloc_hook(s, gfpflags, 1, &object);
>
> Please put this in a code path that is enabled by specifying
>
> slub_debug
>
> on the kernel command line.
I don't understand. First, I had:
if (unlikely(gfpflags & __GFP_ZERO) && object && !WARN_ON_ONCE(s->ctor))
and you didn't like that because it was putting checking into a (semi)fast
path. Now you want me to add a check for slub_debug somewhere? I dont
see an existing one I can leverage that will hit on every allocation.
Perhaps I'm missing something.
next prev parent reply other threads:[~2018-04-11 19:24 UTC|newest]
Thread overview: 23+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-11 6:03 [PATCH v2 0/2] Fix __GFP_ZERO vs constructor Matthew Wilcox
2018-04-11 6:03 ` [PATCH v2 1/2] Fix NULL pointer in page_cache_tree_insert Matthew Wilcox
2018-04-11 6:03 ` [PATCH v2 2/2] slab: __GFP_ZERO is incompatible with a constructor Matthew Wilcox
2018-04-11 6:35 ` Michal Hocko
2018-04-11 13:44 ` Christopher Lameter
2018-04-11 19:24 ` Matthew Wilcox [this message]
2018-04-11 21:11 ` Christopher Lameter
2018-04-11 23:56 ` Matthew Wilcox
2018-04-12 14:10 ` Christopher Lameter
2018-04-12 14:27 ` Matthew Wilcox
2018-04-12 15:15 ` Christopher Lameter
2018-04-12 19:13 ` [PATCH v3 " Matthew Wilcox
2018-04-16 15:10 ` Christopher Lameter
2018-08-03 21:22 ` Guenter Roeck
2018-08-03 22:33 ` Matthew Wilcox
2018-08-03 22:33 ` Matthew Wilcox
2018-08-04 9:28 ` Geert Uytterhoeven
2018-08-04 9:28 ` Geert Uytterhoeven
2018-08-04 14:00 ` Guenter Roeck
2018-08-04 14:00 ` Guenter Roeck
2018-04-12 0:54 ` [PATCH v2 0/2] Fix __GFP_ZERO vs constructor Minchan Kim
2018-04-12 19:24 ` Matthew Wilcox
2018-04-13 12:44 ` Michal Hocko
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