linux-kernel - RE: [PATCH] freezer: fix freeze timeout on exec

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Date:   Fri, 9 Nov 2018 09:29:42 +0900
From:   "Chanho Min" <chanho.min@....com>
To:     "'Oleg Nesterov'" <oleg@...hat.com>
Cc:     "'Rafael J. Wysocki'" <rjw@...ysocki.net>,
        "'Pavel Machek'" <pavel@....cz>,
        "'Len Brown'" <len.brown@...el.com>,
        "'Andrew Morton'" <akpm@...ux-foundation.org>,
        "'Eric W. Biederman'" <ebiederm@...ssion.com>,
        "'Christian Brauner'" <christian@...uner.io>,
        "'Anna-Maria Gleixner'" <anna-maria@...utronix.de>,
        <linux-pm@...r.kernel.org>, <linux-kernel@...r.kernel.org>,
        "'Seungho Park'" <seungho1.park@....com>,
        "'Jongsung Kim'" <neidhard.kim@....com>,
        "'Inkyu Hwang'" <inkyu.hwang@....com>,
        "'donghwan.jung'" <donghwan.jung@....com>
Subject: RE: [PATCH] freezer: fix freeze timeout on exec

> >
> > 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