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From: Christopher Lameter <cl@linux.com>
To: Matthew Wilcox <willy@infradead.org>
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: Thu, 12 Apr 2018 10:15:42 -0500 (CDT)	[thread overview]
Message-ID: <alpine.DEB.2.20.1804121011350.11710@nuc-kabylake> (raw)
In-Reply-To: <20180412142718.GA20398@bombadil.infradead.org>

On Thu, 12 Apr 2018, Matthew Wilcox wrote:

> > Thus the next invocation of the fastpath will find that c->freelist is
> > NULL and go to the slowpath. ...
>
> _ah_.  I hadn't figured out that c->page was always NULL in the debugging
> case too, so ___slab_alloc() always hits the 'new_slab' case.  Thanks!

Also note that you can have SLUB also do the build with all debugging on
without having to use a command like parameter (like SLAB). That requires
CONFIG_SLUB_DEBUG_ON to be set. CONFIG_SLUB_DEBUG is set by default for
all distro builds. It only includes the debug code but does not activate
them by default. Kernel command line parameters allow you to selectively
switch on debugging features for specific slab caches so that you can
limit the latency variations introduced by debugging into the production
kernel. Thus subtle races may be found.

  reply	other threads:[~2018-04-12 15:15 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
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 [this message]
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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