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From:   "Chanho Min" <chanho.min@lge.com>
To:     "'Oleg Nesterov'" <oleg@redhat.com>
Cc:     "'Rafael J. Wysocki'" <rjw@rjwysocki.net>,
        "'Pavel Machek'" <pavel@ucw.cz>,
        "'Len Brown'" <len.brown@intel.com>,
        "'Andrew Morton'" <akpm@linux-foundation.org>,
        "'Eric W. Biederman'" <ebiederm@xmission.com>,
        "'Christian Brauner'" <christian@brauner.io>,
        "'Anna-Maria Gleixner'" <anna-maria@linutronix.de>,
        <linux-pm@vger.kernel.org>, <linux-kernel@vger.kernel.org>,
        "'Seungho Park'" <seungho1.park@lge.com>,
        "'Jongsung Kim'" <neidhard.kim@lge.com>,
        "'Inkyu Hwang'" <inkyu.hwang@lge.com>,
        "'donghwan.jung'" <donghwan.jung@lge.com>
References: <1541671796-8725-1-git-send-email-chanho.min@lge.com> <20181108105030.GB9939@redhat.com>
In-Reply-To: <20181108105030.GB9939@redhat.com>
Subject: RE: [PATCH] freezer: fix freeze timeout on exec
Date:   Fri, 9 Nov 2018 09:29:42 +0900
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> >
> > To fix this, I suggest a patch by emboding the mentioned solution.
> > First, revive and rework cancel_freezing_and_thaw() function whitch
> > stops the task from sleeping in refrigirator reliably. And, The task
> > to be killed does not allow to freeze.
> 
> Can't we simply change de_thread() to use freezable_schedule() ?
> 
> Oleg.

We need to change freezable_schedule_timeout() instead.
freezable_schedule also can't be frozen if sub-threads can't stop
schedule().
Furthermore, I'm not sure if it is safe to freeze it at de_thread().

diff --git a/fs/exec.c b/fs/exec.c
index 9c5ee2a..291cbd6 100644
--- a/fs/exec.c
+++ b/fs/exec.c
@@ -942,7 +942,7 @@ static int de_thread(struct task_struct *tsk)
        while (sig->notify_count) {
                __set_current_state(TASK_KILLABLE);
                spin_unlock_irq(lock);
-               schedule();
+               while (!freezable_schedule_timeout(HZ));
                if (unlikely(__fatal_signal_pending(tsk)))
                        goto killed;
                spin_lock_irq(lock);

Chanho