The patch titled
freezer: fix PF_NOFREEZE vs freezeable race
has been added to the -mm tree. Its filename is
freezer-fix-pf_nofreeze-vs-freezeable-race.patch
*** Remember to use Documentation/SubmitChecklist when testing your code ***
See http://www.zip.com.au/~akpm/linux/patches/stuff/added-to-mm.txt to find
out what to do about this
------------------------------------------------------
Subject: freezer: fix PF_NOFREEZE vs freezeable race
From: Gautham R Shenoy <ego@xxxxxxxxxx>
This patch fixes the race pointed out by Oleg Nesterov.
* Freezer marks a thread as freezeable.
* The thread now marks itself PF_NOFREEZE, but it will be frozen on
on calling try_to_freeze(). Thus the task is frozen, even though it doesn't
want to.
* Subsequent thaw_processes() will also fail to thaw the task since it is
marked PF_NOFREEZE.
Avoid this problem by checking the task's PF_NOFREEZE status in
frozen_processes() before marking the task as frozen.
Signed-off-by: Gautham R Shenoy <ego@xxxxxxxxxx>
Signed-off-by: Rafael J. Wysocki <rjw@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: Pavel Machek <pavel@xxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/freezer.h | 6 ++++--
1 files changed, 4 insertions(+), 2 deletions(-)
diff -puN include/linux/freezer.h~freezer-fix-pf_nofreeze-vs-freezeable-race include/linux/freezer.h
--- a/include/linux/freezer.h~freezer-fix-pf_nofreeze-vs-freezeable-race
+++ a/include/linux/freezer.h
@@ -63,8 +63,10 @@ static inline int thaw_process(struct ta
*/
static inline void frozen_process(struct task_struct *p)
{
- p->flags |= PF_FROZEN;
- wmb();
+ if (!unlikely(p->flags & PF_NOFREEZE)) {
+ p->flags |= PF_FROZEN;
+ wmb();
+ }
clear_tsk_thread_flag(p, TIF_FREEZE);
}
_
Patches currently in -mm which might be from ego@xxxxxxxxxx are
origin.patch
freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch
freezer-close-potential-race-between-refrigerator-and-thaw_tasks.patch
freezer-fix-vfork-problem.patch
freezer-take-kernel_execve-into-consideration.patch
freezer-fix-kthread_create-vs-freezer-theoretical-race.patch
freezer-fix-pf_nofreeze-vs-freezeable-race.patch
freezer-move-frozen_process-to-kernel-power-processc.patch
-
To unsubscribe from this list: send the line "unsubscribe mm-commits" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
