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    SubjectRe: [PATCH AUTOSEL for 4.14 015/161] printk: Add console owner and waiter logic to load balance console writes
    On Thu, Apr 19, 2018 at 04:05:45PM +0200, Jan Kara wrote:
    > On Thu 19-04-18 15:59:43, Greg KH wrote:
    > > On Thu, Apr 19, 2018 at 02:41:33PM +0300, Thomas Backlund wrote:
    > > > Den 16-04-2018 kl. 19:19, skrev Sasha Levin:
    > > > > On Mon, Apr 16, 2018 at 12:12:24PM -0400, Steven Rostedt wrote:
    > > > > > On Mon, 16 Apr 2018 16:02:03 +0000
    > > > > > Sasha Levin <Alexander.Levin@microsoft.com> wrote:
    > > > > >
    > > > > > > One of the things Greg is pushing strongly for is "bug compatibility":
    > > > > > > we want the kernel to behave the same way between mainline and stable.
    > > > > > > If the code is broken, it should be broken in the same way.
    > > > > >
    > > > > > Wait! What does that mean? What's the purpose of stable if it is as
    > > > > > broken as mainline?
    > > > >
    > > > > This just means that if there is a fix that went in mainline, and the
    > > > > fix is broken somehow, we'd rather take the broken fix than not.
    > > > >
    > > > > In this scenario, *something* will be broken, it's just a matter of
    > > > > what. We'd rather have the same thing broken between mainline and
    > > > > stable.
    > > > >
    > > >
    > > > Yeah, but _intentionally_ breaking existing setups to stay "bug compatible"
    > > > _is_ a _regression_ you _really_ _dont_ want in a stable
    > > > supported distro. Because end-users dont care about upstream breaking
    > > > stuff... its the distro that takes the heat for that...
    > > >
    > > > Something "already broken" is not a regression...
    > > >
    > > > As distro maintainer that means one now have to review _every_ patch that
    > > > carries "AUTOSEL", follow all the mail threads that comes up about it, then
    > > > track if it landed in -stable queue, and read every response and possible
    > > > objection to all patches in the -stable queue a second time around... then
    > > > check if it still got included in final stable point relase and then either
    > > > revert them in distro kernel or go track down all the follow-up fixes
    > > > needed...
    > > >
    > > > Just to avoid being "bug compatible with master"
    > >
    > > I've done this "bug compatible" "breakage" more than the AUTOSEL stuff
    > > has in the past, so you had better also be reviewing all of my normal
    > > commits as well :)
    > >
    > > Anyway, we are trying not to do this, but it does, and will,
    > > occasionally happen.
    >
    > Sure, that's understood. So this was just misunderstanding. Sasha's
    > original comment really sounded like "bug compatibility" with current
    > master is desirable and that made me go "Are you serious?" as well...

    As I said before in this thread, yes, sometimes I do this on purpose.

    As an specific example, see a recent bluetooth patch that caused a
    regression on some chromebook devices. The chromeos developers
    rightfully complainied, and I left the commit in there to provide the
    needed "leverage" on the upstream developers to fix this properly.
    Otherwise if I had reverted the stable patch, when people move to a
    newer kernel version, things break, and no one remembers why.

    I also wrote a long response as to _why_ I do this, and even though it
    does happen, why it still is worth taking the stable updates. Please
    see the archives for the full details. I don't want to duplicate this
    again here.

    thanks,

    greg k-h

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