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.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 current task's PF_NOFREEZE status in the
refrigerator before marking current as frozen.
Signed-off-by: Gautham R Shenoy <ego@xxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Cc: "Rafael J. Wysocki" <rjw@xxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
kernel/power/process.c | 9 +++++++++
1 files changed, 9 insertions(+)
diff -puN kernel/power/process.c~fix-pf_nofreeze-and-freezeable-race kernel/power/process.c
--- a/kernel/power/process.c~fix-pf_nofreeze-and-freezeable-race
+++ a/kernel/power/process.c
@@ -41,6 +41,15 @@ void refrigerator(void)
task_lock(current);
if (freezing(current)) {
+ /* check if we had marked ourself PF_NOFREEZE
+ * *after* the freezer did the freezeable() check
+ * on us.
+ */
+ if (current->flags & PF_NOFREEZE) {
+ clear_tsk_thread_flag(current, TIF_FREEZE);
+ task_unlock(current);
+ return;
+ }
frozen_process(current);
task_unlock(current);
} else {
_
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.patch
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