From: Hugh Dickins <hugh@veritas.com>
To: Christoph Lameter <clameter@sgi.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>,
linux-mm@kvack.org, mpm@selenic.com,
Pekka Enberg <penberg@cs.helsinki.fi>
Subject: Re: build error: sparsemem + SLOB
Date: Mon, 20 Nov 2006 17:28:24 +0000 (GMT) [thread overview]
Message-ID: <Pine.LNX.4.64.0611201724340.23537@blonde.wat.veritas.com> (raw)
In-Reply-To: <Pine.LNX.4.64.0611200855280.16845@schroedinger.engr.sgi.com>
On Mon, 20 Nov 2006, Christoph Lameter wrote:
>
> As far as I can tell SLOB is fundamentally racy since it does not support
> SLAB_DESTROY_BY_RCU correctly. F.e. The constructor for the anon_vma will
> be called on alloc without regard for RCU, we free an item and reuse it
> without regard to RCU. This can potentially mess up the anon_vma locking
> state while we access it.
Good find!
> Is SLOB used at all or have we been lucky so far?
Lucky so far. Well, we'd actually have to be quite unlucky to ever
see what page_lock_anon_vma/SLAB_DESTROY_BY_RCU are guarding against.
But you're absolutely right that users should not be exposed to such
unsafety. I'd say SLOB should be disallowed if SMP.
Hugh
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next prev parent reply other threads:[~2006-11-20 17:28 UTC|newest]
Thread overview: 16+ messages / expand[flat|nested] mbox.gz Atom feed top
2006-11-20 5:05 Randy Dunlap
2006-11-20 11:22 ` [PATCH]Re: " Yasunori Goto
2006-11-20 17:02 ` Randy Dunlap
2006-11-20 17:03 ` Christoph Lameter
2006-11-20 17:08 ` Randy Dunlap
2006-11-20 17:28 ` Hugh Dickins [this message]
2006-11-20 18:36 ` Matt Mackall
2006-11-21 5:57 ` Yasunori Goto
2006-11-21 6:59 ` Randy Dunlap
2006-11-21 13:34 ` Hugh Dickins
2006-11-21 19:14 ` Matt Mackall
2006-11-21 19:32 ` Christoph Lameter
2006-11-21 19:29 ` Matt Mackall
2006-11-21 19:54 ` Hugh Dickins
2006-11-20 21:22 ` Christoph Lameter
2006-11-21 13:31 ` Hugh Dickins
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