From: Sergey Senozhatsky <sergey.senozhatsky.work@gmail.com>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Sergey Senozhatsky <sergey.senozhatsky@gmail.com>,
Minchan Kim <minchan@kernel.org>,
Pekka Enberg <penberg@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
Michal Hocko <mhocko@suse.cz>,
David Rientjes <rientjes@google.com>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org,
sergey.senozhatsky.work@gmail.com, Joe Perches <joe@perches.com>
Subject: Re: [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions
Date: Wed, 10 Jun 2015 11:04:44 +0900 [thread overview]
Message-ID: <20150610020444.GA566@swordfish> (raw)
In-Reply-To: <alpine.DEB.2.11.1506092008220.3300@east.gentwo.org>
On (06/09/15 20:11), Christoph Lameter wrote:
> On Tue, 9 Jun 2015, Andrew Morton wrote:
>
> > Well I like it, even though it's going to cause a zillion little cleanup
> > patches.
> >
> > checkpatch already has a "kfree(NULL) is safe and this check is
> > probably not required" test so I guess Joe will need to get busy ;)
> >
> > I'll park these patches until after 4.1 is released - it's getting to
> > that time...
>
> Why do this at all?
this makes things less fragile.
> I understand that kfree/kmem_cache_free can take a
> null pointer but this is the destruction of a cache and it usually
> requires multiple actions to clean things up and these actions have to be
> properly sequenced. All other processors have to stop referencing this
> cache before it can be destroyed.
>I think failing
well, it's not just `failing', it's a NULL pointer deref.
> if someone does something strange like doing cache destruction with a
> NULL pointer is valuable.
>
a missing check is not `something strange'. it's just happening.
(a very quick google search)
http://help.lockergnome.com/linux/PATCH-dlm-NULL-dereference-failure-kmem_cache_create--ftopict555436.html
http://linux-kernel.2935.n7.nabble.com/PATCH-2-6-30-rc6-Remove-kmem-cache-destroy-in-s3c24xx-dma-init-td460417.html
etc.
-ss
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prev parent reply other threads:[~2015-06-10 2:04 UTC|newest]
Thread overview: 44+ messages / expand[flat|nested] mbox.gz Atom feed top
2015-06-09 12:04 [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions Sergey Senozhatsky
2015-06-09 12:04 ` [RFC][PATCH 1/5] mm/slab_common: allow NULL cache pointer in kmem_cache_destroy() Sergey Senozhatsky
2015-06-17 23:14 ` David Rientjes
2015-06-17 23:52 ` Sergey Senozhatsky
2015-06-19 15:50 ` Julia Lawall
2015-08-06 14:21 ` Sergey Senozhatsky
2015-08-06 14:27 ` Julia Lawall
2015-08-06 14:29 ` Sergey Senozhatsky
2015-06-20 16:25 ` Julia Lawall
2015-07-16 8:26 ` Sergey Senozhatsky
2015-06-09 12:04 ` [RFC][PATCH 2/5] mm/mempool: allow NULL `pool' pointer in mempool_destroy() Sergey Senozhatsky
2015-06-17 23:21 ` David Rientjes
2015-06-17 23:54 ` Sergey Senozhatsky
2015-06-09 12:04 ` [RFC][PATCH 3/5] mm/dmapool: allow NULL `pool' pointer in dma_pool_destroy() Sergey Senozhatsky
2015-06-17 23:22 ` David Rientjes
2015-06-09 12:04 ` [RFC][PATCH 4/5] mm/zpool: allow NULL `zpool' pointer in zpool_destroy_pool() Sergey Senozhatsky
2015-06-10 20:59 ` Dan Streetman
2015-06-10 23:58 ` Sergey Senozhatsky
2015-06-11 0:48 ` Joe Perches
2015-06-11 0:59 ` Sergey Senozhatsky
2015-06-11 1:01 ` Dan Streetman
2015-06-09 12:04 ` [RFC][PATCH 5/5] mm/zsmalloc: allow NULL `pool' pointer in zs_destroy_pool() Sergey Senozhatsky
2015-06-09 21:25 ` [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions Andrew Morton
2015-06-10 0:06 ` Joe Perches
2015-06-10 4:39 ` [PATCH] checkpatch: Add some <foo>_destroy functions to NEEDLESS_IF tests Joe Perches
2015-06-10 5:52 ` [PATCH V2] " Joe Perches
2015-06-10 10:18 ` Sergey Senozhatsky
2015-06-11 9:41 ` Julia Lawall
2015-06-11 9:51 ` Sergey Senozhatsky
2015-06-11 9:55 ` Julia Lawall
2015-07-14 23:03 ` Andrew Morton
2015-07-15 0:27 ` Sergey Senozhatsky
2015-06-10 5:46 ` [RFC][PATCH 0/5] do not dereference NULL pools in pools' destroy() functions Julia Lawall
2015-06-10 6:41 ` Sergey Senozhatsky
2015-06-10 6:44 ` Julia Lawall
2015-06-10 6:52 ` Sergey Senozhatsky
2015-06-10 1:11 ` Christoph Lameter
2015-06-10 1:51 ` Andrew Morton
2015-06-10 2:00 ` Christoph Lameter
2015-06-10 2:17 ` Andrew Morton
2015-06-10 4:47 ` Joe Perches
2015-06-11 17:26 ` Christoph Lameter
2015-06-11 17:40 ` Andrew Morton
2015-06-10 2:04 ` Sergey Senozhatsky [this message]
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