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Date: Thu, 2 Nov 2017 15:08:53 +0100
From: Oleg Nesterov <oleg@redhat.com>
To: Miroslav Benes <mbenes@suse.cz>
Cc: Petr Mladek <pmladek@suse.com>, jpoimboe@redhat.com, jeyu@kernel.org,
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        "H. Peter Anvin" <hpa@zytor.com>, Andy Lutomirski <luto@kernel.org>,
        linuxppc-dev@lists.ozlabs.org, x86@kernel.org
Subject: Re: [PATCH v3 1/2] livepatch: send a fake signal to all blocking
 tasks
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On 11/02, Miroslav Benes wrote:
>
> On Wed, 1 Nov 2017, Oleg Nesterov wrote:
>
> > Note also that wake_up_state(TASK_INTERRUPTIBLE) won't wakeup the TASK_IDLE
> > kthreads, and most of the kthreads which use TASK_INTERRUPTIBLE should use
> > TASK_IDLE today, because in most cases TASK_INTERRUPTIBLE was used to not
> > contribute to loadavg.
>
> Yes. Unfortunately, we have TASK_IDLE for more than two years now and
> nothing much has happened yet. TASK_IDLE is still used sporadically. I'd
> like to be on the safe side with livepatch

OK, as I said I won't argue,

> and given that
> TASK_INTERRUPTIBLE loops should be prepared for spurious wakeups by
> definition,

Not really when it comes to kthreads.

Once again, unless kthread does allow_signal() TASK_INTERRUPTIBLE does
not really differ from TASK_UNINTERRUPTIBLE except the latter contributes
to loadavg. And that is why TASK_INTERRUPTIBLE was commonly used instead
of TASK_UNINTERRUPTIBLE, so I do not think that TASK_INTERRUPTIBLE loops
are more ready in general than TASK_UNINTERRUPTIBLE.

Oleg.