Re: [RFC PATCH] mm, oom: distinguish blockable mode for mmu notifiers

From: Michal Hocko <mhocko@kernel.org>
To: "Christian König" <christian.koenig@amd.com>
Cc: kvm@vger.kernel.org, "Radim Krčmář" <rkrcmar@redhat.com>,
	"David Airlie" <airlied@linux.ie>,
	"Sudeep Dutt" <sudeep.dutt@intel.com>,
	dri-devel@lists.freedesktop.org, linux-mm@kvack.org,
	"Andrea Arcangeli" <aarcange@redhat.com>,
	"David (ChunMing) Zhou" <David1.Zhou@amd.com>,
	"Dimitri Sivanich" <sivanich@sgi.com>,
	linux-rdma@vger.kernel.org, amd-gfx@lists.freedesktop.org,
	"Jason Gunthorpe" <jgg@ziepe.ca>,
	"Doug Ledford" <dledford@redhat.com>,
	"David Rientjes" <rientjes@google.com>,
	xen-devel@lists.xenproject.org, intel-gfx@lists.freedesktop.org,
	"Jérôme Glisse" <jglisse@redhat.com>,
	"Rodrigo Vivi" <rodrigo.vivi@intel.com>,
	"Boris Ostrovsky" <boris.ostrovsky@oracle.com>,
	"Juergen Gross" <jgross@suse.com>,
	"Mike Marciniszyn" <mike.marciniszyn@intel.com>,
	"Dennis Dalessandro" <dennis.dalessandro@intel.com>,
	LKML <linux-kernel@vger.kernel.org>
Subject: Re: [RFC PATCH] mm, oom: distinguish blockable mode for mmu notifiers
Date: Mon, 2 Jul 2018 13:54:23 +0200	[thread overview]
Message-ID: <20180702115423.GK19043@dhcp22.suse.cz> (raw)
In-Reply-To: <71f4184c-21ea-5af1-eeb6-bf7787614e2d@amd.com>

On Mon 02-07-18 11:14:58, Christian König wrote:
> Am 27.06.2018 um 09:44 schrieb Michal Hocko:
> > This is the v2 of RFC based on the feedback I've received so far. The
> > code even compiles as a bonus ;) I haven't runtime tested it yet, mostly
> > because I have no idea how.
> > 
> > Any further feedback is highly appreciated of course.
> 
> That sounds like it should work and at least the amdgpu changes now look
> good to me on first glance.
> 
> Can you split that up further in the usual way? E.g. adding the blockable
> flag in one patch and fixing all implementations of the MMU notifier in
> follow up patches.

But such a code would be broken, no? Ignoring the blockable state will
simply lead to lockups until the fixup parts get applied.
Is the split up really worth it? I was thinking about that but had hard
times to end up with something that would be bisectable. Well, except
for returning -EBUSY until all notifiers are implemented. Which I found
confusing.

> This way I'm pretty sure Felix and I can give an rb on the amdgpu/amdkfd
> changes.

If you are worried to give r-b only for those then this can be done even
for larger patches. Just make your Reviewd-by more specific
R-b: name # For BLA BLA
-- 
Michal Hocko
SUSE Labs
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