From: Christopher Lameter <cl@linux.com>
To: Matthew Wilcox <willy@infradead.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>,
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>,
stable@vger.kernel.org
Subject: Re: [PATCH 1/2] slab: __GFP_ZERO is incompatible with a constructor
Date: Tue, 10 Apr 2018 15:21:45 -0500 (CDT) [thread overview]
Message-ID: <alpine.DEB.2.20.1804101512350.30225@nuc-kabylake> (raw)
In-Reply-To: <20180410175011.GE3614@bombadil.infradead.org>
On Tue, 10 Apr 2018, Matthew Wilcox wrote:
> > Objects can be freed and reused and still be accessed from code that
> > thinks the object is the old and not the new object....
>
> Yes, I know, that's the point of RCU typesafety. My point is that an
> object *which has never been used* can't be accessed. So you don't *need*
> a constructor.
But the object needs to have the proper contents after it was released and
re-allocated. Some objects may rely on contents (like list heads)
surviving the realloc process because access must always be possible.
validate_slab() checks on proper metadata content in a slab
although it does not access the payload. So that may work you separate
the payload init from the metadata init.
next prev parent reply other threads:[~2018-04-10 20:21 UTC|newest]
Thread overview: 22+ messages / expand[flat|nested] mbox.gz Atom feed top
2018-04-10 12:53 Matthew Wilcox
2018-04-10 12:53 ` [PATCH 2/2] page cache: Mask off unwanted GFP flags Matthew Wilcox
2018-04-10 13:08 ` Johannes Weiner
2018-04-10 13:09 ` Michal Hocko
2018-04-10 13:45 ` Minchan Kim
2018-04-10 14:02 ` Matthew Wilcox
2018-04-10 15:18 ` Jaegeuk Kim
2018-04-10 13:46 ` Jan Kara
2018-04-10 13:00 ` [PATCH 1/2] slab: __GFP_ZERO is incompatible with a constructor Johannes Weiner
2018-04-10 13:07 ` Michal Hocko
2018-04-10 13:40 ` Vlastimil Babka
2018-04-10 13:53 ` Eric Dumazet
2018-04-10 16:50 ` Matthew Wilcox
2018-04-10 17:30 ` Christopher Lameter
2018-04-10 17:38 ` Matthew Wilcox
2018-04-10 17:45 ` Christopher Lameter
2018-04-10 17:50 ` Matthew Wilcox
2018-04-10 20:21 ` Christopher Lameter [this message]
2018-04-10 14:21 ` Christopher Lameter
2018-04-10 14:26 ` Christopher Lameter
2018-04-10 15:54 ` Matthew Wilcox
2018-04-10 17:04 ` Christopher Lameter
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