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[99.254.144.39]) by smtp.gmail.com with ESMTPSA id e30-20020a0caa5e000000b0063d10086876sm4807945qvb.115.2023.08.01.10.05.02 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 01 Aug 2023 10:05:03 -0700 (PDT) Date: Tue, 1 Aug 2023 13:04:50 -0400 From: Peter Xu To: David Hildenbrand Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, kvm@vger.kernel.org, linux-kselftest@vger.kernel.org, Andrew Morton , Linus Torvalds , liubo , Matthew Wilcox , Hugh Dickins , Jason Gunthorpe , John Hubbard , Mel Gorman , Shuah Khan , Paolo Bonzini , stable@vger.kernel.org Subject: Re: [PATCH v2 1/8] mm/gup: reintroduce FOLL_NUMA as FOLL_HONOR_NUMA_FAULT Message-ID: References: <20230801124844.278698-1-david@redhat.com> <20230801124844.278698-2-david@redhat.com> <30d86a2d-4af2-d840-91be-2e68c73a07bd@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <30d86a2d-4af2-d840-91be-2e68c73a07bd@redhat.com> Precedence: bulk List-ID: X-Mailing-List: kvm@vger.kernel.org On Tue, Aug 01, 2023 at 06:15:48PM +0200, David Hildenbrand wrote: > On 01.08.23 17:48, Peter Xu wrote: > > On Tue, Aug 01, 2023 at 02:48:37PM +0200, David Hildenbrand wrote: > > > @@ -2240,6 +2244,12 @@ static bool is_valid_gup_args(struct page **pages, int *locked, > > > gup_flags |= FOLL_UNLOCKABLE; > > > } > > > + /* > > > + * For now, always trigger NUMA hinting faults. Some GUP users like > > > + * KVM really require it to benefit from autonuma. > > > + */ > > > + gup_flags |= FOLL_HONOR_NUMA_FAULT; > > > > Since at it, do we want to not set it for FOLL_REMOTE, which still sounds > > like a good thing to have? > > I thought about that, but decided against making that patch here more > complicated to eventually rip it again all out in #4. I thought that was the whole point of having patch 4 separate, because we should assume patch 4 may not exist in (at least) some trees, so I ignored patch 4 when commenting here, and we should not assume it's destined to be removed here. > > I fully agree that FOLL_REMOTE does not make too much sense, but let's > rather keep it simple for this patch. It's fine - I suppose this patch fixes whatever we're aware of that's broken with FOLL_NUMA's removal, so it can even be anything on top when needed. I assume I'm happy to ack this with/without that change, then: Acked-by: Peter Xu PS: I still hope that the other oneliner can be squashed here directly; it literally changes exact the same line above so reading this patch alone can be affected. You said there you didn't want the commit message to be too long here, but this is definitely not long at all! I bet you have similar understanding to me on defining "long commit message". :) I'd never worry that. Your call. Thanks, -- Peter Xu