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From:   "Chanho Min" <chanho.min@lge.com>
To:     "'Oleg Nesterov'" <oleg@redhat.com>,
        "'Ingo Molnar'" <mingo@kernel.org>
Cc:     "'Linus Torvalds'" <torvalds@linux-foundation.org>,
        "'Linux List Kernel Mailing'" <linux-kernel@vger.kernel.org>,
        "'Rafael J. Wysocki'" <rafael.j.wysocki@intel.com>,
        "'Thomas Gleixner'" <tglx@linutronix.de>,
        "'Peter Zijlstra'" <a.p.zijlstra@chello.nl>,
        "'Pavel Machek'" <pavel@ucw.cz>,
        "'Michal Hocko'" <mhocko@suse.com>, <seungho1.park@lge.com>
References: <CAHk-=wgdsXyCaLsFEpyUpAeRqVS69u=xo4rzEN+cS=xwz2gajg@mail.gmail.com> <20181203074700.GA21240@gmail.com> <20181203115601.GA31795@redhat.com> <20181204091736.GD73770@gmail.com> <20181205143618.GA9535@redhat.com>
In-Reply-To: <20181205143618.GA9535@redhat.com>
Subject: RE: [PATCH] Revert "exec: make de_thread() freezable (was: Re: Linux 4.20-rc4)
Date:   Thu, 6 Dec 2018 17:54:09 +0900
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> From: Oleg Nesterov [mailto:oleg@redhat.com]
> Sent: Wednesday, December 05, 2018 11:36 PM
> To: Ingo Molnar
> Cc: Linus Torvalds; Linux List Kernel Mailing; Rafael J. Wysocki; Chanho Min;
> Thomas Gleixner; Peter Zijlstra; Pavel Machek; Michal Hocko
> Subject: Re: [PATCH] Revert "exec: make de_thread() freezable (was: Re: Linux
> 4.20-rc4)
> 
> Ingo, et al,
> 
> Sorry, I am sick and can't participate this discussion right now,
> 
> On 12/04, Ingo Molnar wrote:
> >
> > * Oleg Nesterov <oleg@redhat.com> wrote:
> >
> > > we really need to narrow the (huge) scope of ->cred_guard_mutex in exec
> paths.
> > >
> > > my attempt to fix this was nacked, and nobody suggested a better solution
> so far.
> >
> > Any link to your patch and the NAK?
> 
> See https://lore.kernel.org/lkml/20170213141452.GA30203@redhat.com/
> 
> No questions, the patch wasn't pretty. And imo we need to rework the security
> hooks in the long term.
> 
> Oleg.

I am sorry for the reverting this patch. It's also my fault that
I didn't check lockdep. But, We decided to keep this patch in our product.
Freeze fail is a real problem we've had for the last two years,
whereas lockdep's notice is not a real problem.
We hope this issue will be resolved soon.

Special thanks to Oleg,
Chanho