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Date:   Thu, 15 Oct 2020 17:27:08 +0200
From:   Oleg Nesterov <oleg@redhat.com>
To:     Thomas Gleixner <tglx@linutronix.de>
Cc:     Jens Axboe <axboe@kernel.dk>, linux-kernel@vger.kernel.org,
        io-uring@vger.kernel.org, peterz@infradead.org
Subject: Re: [PATCH 3/5] kernel: add support for TIF_NOTIFY_SIGNAL
Message-ID: <20201015152707.GL24156@redhat.com>
References: <20201015131701.511523-1-axboe@kernel.dk>
 <20201015131701.511523-4-axboe@kernel.dk>
 <20201015143151.GB24156@redhat.com>
 <5d231aa1-b8c7-ae4e-90bb-211f82b57547@kernel.dk>
 <20201015143728.GE24156@redhat.com>
 <87r1pzv8hy.fsf@nanos.tec.linutronix.de>
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On 10/15, Thomas Gleixner wrote:
>
> On Thu, Oct 15 2020 at 16:37, Oleg Nesterov wrote:
> > On 10/15, Jens Axboe wrote:
> >> On 10/15/20 8:31 AM, Oleg Nesterov wrote:
> >> > I don't understand why does this version requires CONFIG_GENERIC_ENTRY.
> >> >
> >> > Afaics, it is very easy to change all the non-x86 arches to support
> >> > TIF_NOTIFY_SIGNAL, but it is not trivial to change them all to use
> >> > kernel/entry/common.c ?
> >>
> >> I think that Thomas wants to gate TIF_NOTIFY_SIGNAL on conversion to
> >> the generic entry code?
> >
> > Then I think TIF_NOTIFY_SIGNAL will be never fully supported ;)
>
> Yeah, we proliferate crap on that basis forever. _ALL_ architectures
> have the very same entry/exit ordering problems (or subsets and
> different ones) which we fixed on x86.
>
> So no, we don't want to have 24 different variants of the same thing
> again. That's what common code is for.
>
> Not doing that is making the life of everyone working on core
> infrastructure pointlessly harder. Architecture people still have enough
> ways to screw everyone up.

Sure, it would be nice to change them all to use kernel/entry/common.c.

Until then (until never), how can we kill JOBCTL_TASK_WORK ?

How can we remove freezing/klp_patch_pending from recalc_sigpending() ?

Oleg.