From: Tejun Heo <tj@kernel.org>
To: rjw@sisk.pl, paul@paulmenage.org, linux-kernel@vger.kernel.org,
linux-pm@vger.kernel.org
Cc: arnd@arndb.de, oleg@redhat.com, matthltc@us.ibm.com,
Tejun Heo <tj@kernel.org>
Subject: [PATCH 06/17] freezer: remove racy clear_freeze_flag() and set PF_NOFREEZE on dead tasks
Date: Mon, 31 Oct 2011 12:05:17 -0700 [thread overview]
Message-ID: <1320087928-32307-7-git-send-email-tj@kernel.org> (raw)
In-Reply-To: <1320087928-32307-1-git-send-email-tj@kernel.org>
clear_freeze_flag() in exit_mm() is racy. Freezing can start
afterwards. Remove it. Skipping freezer for exiting task will be
properly implemented later.
Also, freezable() was testing exit_state directly to make system
freezer ignore dead tasks. Let the exiting task set PF_NOFREEZE after
entering TASK_DEAD instead.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Oleg Nesterov <oleg@redhat.com>
---
kernel/exit.c | 3 +--
kernel/power/process.c | 3 +--
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/kernel/exit.c b/kernel/exit.c
index 2913b35..3d6f570 100644
--- a/kernel/exit.c
+++ b/kernel/exit.c
@@ -679,8 +679,6 @@ static void exit_mm(struct task_struct * tsk)
tsk->mm = NULL;
up_read(&mm->mmap_sem);
enter_lazy_tlb(mm, current);
- /* We don't want this task to be frozen prematurely */
- clear_freeze_flag(tsk);
if (tsk->signal->oom_score_adj == OOM_SCORE_ADJ_MIN)
atomic_dec(&mm->oom_disable_count);
task_unlock(tsk);
@@ -1042,6 +1040,7 @@ NORET_TYPE void do_exit(long code)
exit_rcu();
/* causes final put_task_struct in finish_task_switch(). */
tsk->state = TASK_DEAD;
+ tsk->flags |= PF_NOFREEZE; /* tell freezer to ignore us */
schedule();
BUG();
/* Avoid "noreturn function does return". */
diff --git a/kernel/power/process.c b/kernel/power/process.c
index fe27872..23822dc 100644
--- a/kernel/power/process.c
+++ b/kernel/power/process.c
@@ -25,8 +25,7 @@
static inline int freezable(struct task_struct * p)
{
if ((p == current) ||
- (p->flags & PF_NOFREEZE) ||
- (p->exit_state != 0))
+ (p->flags & PF_NOFREEZE))
return 0;
return 1;
}
--
1.7.3.1
next prev parent reply other threads:[~2011-10-31 19:05 UTC|newest]
Thread overview: 29+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-10-31 19:05 [PATCHSET pm] freezer: fix various bugs and simplify implementation, take#2 Tejun Heo
2011-10-31 19:05 ` [PATCH 01/17] freezer: fix current->state restoration race in refrigerator() Tejun Heo
2011-10-31 19:05 ` [PATCH 02/17] freezer: don't unnecessarily set PF_NOFREEZE explicitly Tejun Heo
2011-10-31 19:05 ` [PATCH 03/17] freezer: unexport refrigerator() and update try_to_freeze() slightly Tejun Heo
2011-10-31 19:05 ` [PATCH 04/17] freezer: implement and use kthread_freezable_should_stop() Tejun Heo
2011-10-31 19:05 ` [PATCH 05/17] freezer: rename thaw_process() to __thaw_task() and simplify the implementation Tejun Heo
2011-11-06 12:04 ` Srivatsa S. Bhat
2011-11-06 16:51 ` Tejun Heo
2011-11-06 17:10 ` Srivatsa S. Bhat
2011-10-31 19:05 ` Tejun Heo [this message]
2011-10-31 19:05 ` [PATCH 07/17] freezer: don't distinguish nosig tasks on thaw Tejun Heo
2011-10-31 19:05 ` [PATCH 08/17] freezer: use dedicated lock instead of task_lock() + memory barrier Tejun Heo
2011-10-31 19:05 ` [PATCH 09/17] freezer: make freezing indicate freeze condition in effect Tejun Heo
2011-10-31 19:05 ` [PATCH 10/17] freezer: test freezable conditions while holding freezer_lock Tejun Heo
2011-10-31 19:05 ` [PATCH 11/17] freezer: kill PF_FREEZING Tejun Heo
2011-10-31 19:05 ` [PATCH 12/17] freezer: clean up freeze_processes() failure path Tejun Heo
2011-11-03 19:09 ` Srivatsa S. Bhat
2011-11-03 22:25 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 13/17] cgroup_freezer: prepare for removal of TIF_FREEZE Tejun Heo
2011-10-31 22:33 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 14/17] freezer: make freezing() test freeze conditions in effect instead " Tejun Heo
2011-10-31 22:34 ` [PATCH UPDATED " Tejun Heo
2011-10-31 19:05 ` [PATCH 15/17] freezer: remove now unused TIF_FREEZE Tejun Heo
2011-10-31 19:05 ` [PATCH 16/17] freezer: remove should_send_signal() and update frozen() Tejun Heo
2011-10-31 19:05 ` [PATCH 17/17] freezer: fix set_freezable[_with_signal]() race Tejun Heo
2011-10-31 22:34 ` [PATCH 18/17] freezer: restructure __refrigerator() Tejun Heo
2011-10-31 22:35 ` [PATCH 19/17] freezer: use lock_task_sighand() in fake_signal_wake_up() Tejun Heo
2011-10-31 22:35 ` [PATCH UPDATED 20/17] freezer: remove unused @sig_only from freeze_task() Tejun Heo
2011-10-31 22:40 ` [PATCHSET UPDATED pm] freezer: fix various bugs and simplify implementation, take#2 Tejun Heo
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