linux-kernel - Re: [Intel-gfx] [PATCH 2/5] kernel.h: Add non_block

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Message-ID: <20190816165455.GG5398@ziepe.ca>
Date:   Fri, 16 Aug 2019 13:54:55 -0300
From:   Jason Gunthorpe <jgg@...pe.ca>
To:     Daniel Vetter <daniel@...ll.ch>
Cc:     Michal Hocko <mhocko@...nel.org>, Feng Tang <feng.tang@...el.com>,
        Randy Dunlap <rdunlap@...radead.org>,
        Kees Cook <keescook@...omium.org>,
        Masahiro Yamada <yamada.masahiro@...ionext.com>,
        Peter Zijlstra <peterz@...radead.org>,
        Intel Graphics Development <intel-gfx@...ts.freedesktop.org>,
        Jann Horn <jannh@...gle.com>,
        LKML <linux-kernel@...r.kernel.org>,
        DRI Development <dri-devel@...ts.freedesktop.org>,
        Linux MM <linux-mm@...ck.org>,
        Jérôme Glisse <jglisse@...hat.com>,
        Ingo Molnar <mingo@...hat.com>,
        Thomas Gleixner <tglx@...utronix.de>,
        David Rientjes <rientjes@...gle.com>,
        Wei Wang <wvw@...gle.com>,
        Daniel Vetter <daniel.vetter@...el.com>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Andy Shevchenko <andriy.shevchenko@...ux.intel.com>,
        Christian König <christian.koenig@....com>
Subject: Re: [Intel-gfx] [PATCH 2/5] kernel.h: Add non_block_start/end()

On Fri, Aug 16, 2019 at 06:36:52PM +0200, Daniel Vetter wrote:
> On Fri, Aug 16, 2019 at 4:38 PM Jason Gunthorpe <jgg@...pe.ca> wrote:
> >
> > On Fri, Aug 16, 2019 at 04:11:34PM +0200, Daniel Vetter wrote:
> > > Also, aside from this patch (which is prep for the next) and some
> > > simple reordering conflicts they're all independent. So if there's no
> > > way to paint this bikeshed here (technicolor perhaps?) then I'd like
> > > to get at least the others considered.
> >
> > Sure, I think for conflict avoidance reasons I'm probably taking
> > mmu_notifier stuff via hmm.git, so:
> >
> > - Andrew had a minor remark on #1, I am ambivalent and would take it
> >   as-is. Your decision if you want to respin.
> 
> I like mine better, see also the reply from Ralph Campbell.

Sure

> > - #2/#3 is this issue, I would stand by the preempt_disable/etc path
> >   Our situation matches yours, debug tests run lockdep/etc.
>
> Since Michal requested the current flavour I think we need spin a bit
> more on these here. I guess I'll just rebase them to the end so
> they're not holding up the others.
> 
> > - #4 I like a lot, except the map should enclose range_end too,
> >   this can be done after the mm_has_notifiers inside the
> >   __mmu_notifier function
> 
> To make sure I get this right: The same lockdep context, but also
> wrapped around invalidate_range_end? 

Yes, the locking context of _range_start and _range_end should be
identical, last time I checked callers this was the case.

So, just add it to __mmu_notifier_invalidate_range_end() outside the
SRCU as there is no reason to burden debug kernel callers twice when
mmu notifiers are not enabled

Jason