From: Oleg Nesterov <oleg@tv-sign.ru>
Date: Thu, 1 Mar 2007 04:13:49 +0000 (-0800)
Subject: [PATCH] adapt page_lock_anon_vma() to PREEMPT_RCU
X-Git-Tag: v2.6.21-rc3~157
X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=34bbd704051c9d053d69e90569a3a2365f4c7b50;p=pandora-kernel.git

[PATCH] adapt page_lock_anon_vma() to PREEMPT_RCU

page_lock_anon_vma() uses spin_lock() to block RCU.  This doesn't work with
PREEMPT_RCU, we have to do rcu_read_lock() explicitely.  Otherwise, it is
theoretically possible that slab returns anon_vma's memory to the system
before we do spin_unlock(&anon_vma->lock).

[ Hugh points out that this only matters for PREEMPT_RCU, which isn't merged
  yet, and may never be.  Regardless, this patch is conceptually the
  right thing to do, even if it doesn't matter at this point.  - Linus ]

Signed-off-by: Oleg Nesterov <oleg@tv-sign.ru>
Cc: Paul McKenney <paulmck@linux.vnet.ibm.com>
Cc: Nick Piggin <nickpiggin@yahoo.com.au>
Cc: Christoph Lameter <clameter@engr.sgi.com>
Acked-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
---

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