The patch titled
Fix PF_NOFREEZE and freezeable race
has been added to the -mm tree. Its filename is
fix-pf_nofreeze-and-freezeable-race-2.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: Fix PF_NOFREEZE and 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 causing it to
freeze 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>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/freezer.h | 6 ++++--
1 file changed, 4 insertions(+), 2 deletions(-)
diff -puN include/linux/freezer.h~fix-pf_nofreeze-and-freezeable-race-2 include/linux/freezer.h
--- a/include/linux/freezer.h~fix-pf_nofreeze-and-freezeable-race-2
+++ a/include/linux/freezer.h
@@ -57,8 +57,10 @@ 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
i386-avoid-checking-for-cpu-gone-when-config_hotplug_cpu-not-defined.patch
flush_workqueue-use-preempt_disable-to-hold-off-cpu-hotplug.patch
flush_cpu_workqueue-dont-flush-an-empty-worklist.patch
extend-notifier_call_chain-to-count-nr_calls-made.patch
define-and-use-new-eventscpu_lock_acquire-and-cpu_lock_release.patch
eliminate-lock_cpu_hotplug-in-kernel-schedc.patch
call-cpu_chain-with-cpu_down_failed-if-cpu_down_prepare-failed.patch
slab-use-cpu_lock_.patch
workqueue-fix-freezeable-workqueues-implementation.patch
workqueue-fix-flush_workqueue-vs-cpu_dead-race.patch
workqueue-dont-clear-cwq-thread-until-it-exits.patch
workqueue-dont-migrate-pending-works-from-the-dead-cpu.patch
freezer-read-pf_borrowed_mm-in-a-nonracy-way.patch
freezer-close-theoretical-race-between-refrigerator-and-thaw_tasks.patch
freezer-remove-pf_nofreeze-from-rcutorture-thread.patch
freezer-remove-pf_nofreeze-from-bluetooth-threads.patch
freezer-add-try_to_freeze-calls-to-all-kernel-threads.patch
freezer-fix-vfork-problem.patch
freezer-take-kernel_execve-into-consideration.patch
fix-pf_nofreeze-and-freezeable-race-2.patch
freezer-document-task_lock-in-thaw_process.patch
add-suspend-related-notifications-for-cpu-hotplug.patch
microcode-use-suspend-related-cpu-hotplug-notifications.patch
-
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