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Wed, 12 Aug 2026 19:26:10 -0700 (PDT) Date: Wed, 12 Aug 2026 22:26:08 -0400 From: Gregory Price To: SJ Park Cc: "Lorenzo Stoakes (ARM)" , linux-mm@kvack.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, npache@redhat.com, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, vbabka@kernel.org, jannh@google.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, ying.huang@linux.alibaba.com, apopple@nvidia.com Subject: Re: [PATCH 1/4] mm/damon: defensively skip zone device folios in damon_get_folio() Message-ID: References: <20260807000938.79851-1-sj@kernel.org> Precedence: bulk X-Mailing-List: damon@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260807000938.79851-1-sj@kernel.org> On Thu, Aug 06, 2026 at 05:09:37PM -0700, SJ Park wrote: > On Thu, 6 Aug 2026 12:05:00 -0500 Gregory Price wrote: > > > On Thu, Aug 06, 2026 at 02:37:59PM +0100, Lorenzo Stoakes (ARM) wrote: > > > On Tue, Jul 28, 2026 at 03:47:11PM -0400, Gregory Price wrote: > > > > All DAMON physical- and virtual-address operations obtain their folios > > > > through damon_get_folio(). That helper already excludes ZONE_DEVICE > > > > memory implicitly via pfn_to_online_page() and folio_test_lru(), but > > > > this is inconsistent with other callers in mm/ which test explicitly. > > > > > > > > Add an explicit folio_is_zone_device() rejection in damon_get_folio() > > > > so the guarantee lives in one place and covers every caller uniformly, > > > > consistent with other mm walkers that reject zone device folios. > > > > > > > > Signed-off-by: Gregory Price (Meta) > > > > > > Thanks, nice to make it explicit! > > > > > > Acked-by: Lorenzo Stoakes (ARM) > > > > > > > SJ Asked me to drop it, > > I didn't asked you to drop this. I asked your thought about revisioning this > for my concern. And you replied [1] you can drop this. > Sorry I didn't mean to imply you pushed for one side or another, just that the feedback you gave about not wanting dead code is reason enough to drop it. I will probably just go ahead and drop it unless Lorenzo thinks the patch is worth keeping. In my next private node iteration, it ends up back in anyway - so we get a two for one without the intermediate patch. ~Gregory