linux-kernel - Re: Potential scheduler regression

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Date:   Thu, 13 Jul 2017 15:24:02 -0400
From:   Ben Guthro <ben@...hro.net>
To:     Greg KH <gregkh@...uxfoundation.org>
Cc:     Ingo Molnar <mingo@...nel.org>,
        Peter Zijlstra <peterz@...radead.org>,
        Linux Kernel Mailing List <linux-kernel@...r.kernel.org>,
        Linus Torvalds <torvalds@...ux-foundation.org>,
        Mike Galbraith <efault@....de>,
        Thomas Gleixner <tglx@...utronix.de>
Subject: Re: Potential scheduler regression

On Tue, Jul 11, 2017 at 5:55 AM, Greg KH <gregkh@...uxfoundation.org> wrote:
> On Tue, Jul 11, 2017 at 10:30:14AM +0200, Ingo Molnar wrote:
>>
>> * Ben Guthro <ben@...hro.net> wrote:
>>
>> > > If people have experience with these in the "enterprise" distros, or any other
>> > > tree, and want to provide me with backported, and tested, patches, I'll be
>> > > glad to consider them for stable kernels.
>> > >
>> > > thanks,
>> > >
>> > > greg k-h
>> >
>> > I tried to do a simple cherry-pick of the suggested patches - but they
>> > apply against files that don't exist in the 4.9 series.
>>
>> I think there are only two strategies to maintain a backport which work in the
>> long run:
>>
>>  - insist on the simplest fixes and pure cherry-picks
>>
>>  - or pick up _everything_ to sync up the two versions.
>>
>> The latter would mean a lot of commits - and I'm afraid it would also involve the
>> scheduler header split-up, which literally involves hundreds of files plus
>> perpetual build-breakage risk, so it's a no-no.
>>
>> > In my release of 4.9 - I'm planning on doing the simpler revert of 1b568f0aab
>> > that introduced the performance degradation, rather than pulling in lots of code
>> > from newer kernels.
>>
>> That sounds much saner - I'd even Ack that approach for -stable as a special
>> exception, than to complicate things with excessive backports.
>
> Ok, I'll revert that for the next stable release after this one that is
> currently under review.
>
> thanks,
>
> greg k-h

Greg,

Just for clarity - is the "next one" 4.9.38 (posted today for review)
- or the one following?

Thanks,
Ben