From 15f311fd0fd20ab3458062d284bb9c7663c3a122 Mon Sep 17 00:00:00 2001
From: Paul Gortmaker <paul.gortmaker@windriver.com>
Date: Wed, 19 Jan 2011 22:52:26 -0500
Subject: [PATCH] mmu_context: add preempt_disable to use_mm()

This is one of several extractions from the merge up to 33-rc8.

See it in a git tip repo with:

   git diff 5f854cfc024622e4aae14d7cf422f6ff86278688^2 \
	5f854cfc024622e4aae14d7cf422f6ff86278688 mm/mmu_context.c

You can find the origin of this change in the tip merge commit:

     commit 5f854cfc024622e4aae14d7cf422f6ff86278688
     Merge: cc24da0 4ec62b2
     Author: Thomas Gleixner <tglx@linutronix.de>
     Date:   Sun Feb 21 20:17:22 2010 +0100

         Forward to 2.6.33-rc8

         Merge branch 'linus' into rt/head with a pile of conflicts.

         Signed-off-by: Thomas Gleixner <tglx@linutronix.de>

Normally there are not significant changes/additions in a merge commit that
are not from any other "normal" commit.  But in this case there are, so
break them out into separate explicit commits.

Signed-off-by: Paul Gortmaker <paul.gortmaker@windriver.com>

diff --git a/mm/mmu_context.c b/mm/mmu_context.c
index ded9081..fa3d693 100644
--- a/mm/mmu_context.c
+++ b/mm/mmu_context.c
@@ -25,6 +25,7 @@ void use_mm(struct mm_struct *mm)
 	struct task_struct *tsk = current;
 
 	task_lock(tsk);
+	preempt_disable();
 	active_mm = tsk->active_mm;
 	if (active_mm != mm) {
 		atomic_inc(&mm->mm_count);
@@ -32,6 +33,7 @@ void use_mm(struct mm_struct *mm)
 	}
 	tsk->mm = mm;
 	switch_mm(active_mm, mm, tsk);
+	preempt_enable();
 	task_unlock(tsk);
 
 	if (active_mm != mm)
-- 
1.7.1.1