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Subject[PATCH 1/7] Freezer: Read PF_BORROWED_MM in a nonracy way
Date
From: Rafael J. Wysocki <rjw@sisk.pl>

The reading of PF_BORROWED_MM in is_user_space() without task_lock() is racy.
Fix it.

Signed-off-by: Rafael J. Wysocki <rjw@sisk.pl>
Acked-by: Pavel Machek <pavel@ucw.cz>
---
kernel/power/process.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
Index: linux-2.6/kernel/power/process.c
===================================================================
--- linux-2.6.orig/kernel/power/process.c 2007-05-10 21:44:23.000000000 +0200
+++ linux-2.6/kernel/power/process.c 2007-05-10 21:44:28.000000000 +0200
@@ -8,6 +8,7 @@

#undef DEBUG

+#include <linux/sched.h>
#include <linux/interrupt.h>
#include <linux/suspend.h>
#include <linux/module.h>
@@ -88,7 +89,12 @@ static void cancel_freezing(struct task_

static inline int is_user_space(struct task_struct *p)
{
- return p->mm && !(p->flags & PF_BORROWED_MM);
+ int ret;
+
+ task_lock(p);
+ ret = p->mm && !(p->flags & PF_BORROWED_MM);
+ task_unlock(p);
+ return ret;
}

static unsigned int try_to_freeze_tasks(int freeze_user_space)
-
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