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b=NZzxC51QwJ4HjDg4ylYDO1RhiuPNVDAiyi/Qp2vbT/LeJC+CS9MU+FtrmQXgLrbmG 3B/cGawdM5aM8ETI5tETxhCV4iPEZDEQRE1VMt2Ho/gqmcdKLZDLMATzHnhO9fyGaT V6UPD0wiNtHQi/hwuS4GFHzMG9GXgOqEtH6kaCWqrtLLo2FHORfbtyc/7YxZlFMRSF fQRe0aHDpeT9NNjnrhriqVYxXAcYCS+fcYucDJ9DkNTEg5LFO+jB3DnyF0ybRd8GT6 YmdSBSRr6KeLKkX4lavQ32yZ4jTRpt34WHUHZhqV0WANllyHOymgKXsBypISDLRge8 ByyqAT58/NUWQ== Date: Thu, 6 Aug 2026 14:37:59 +0100 From: "Lorenzo Stoakes (ARM)" To: Gregory Price Cc: linux-mm@kvack.org, damon@lists.linux.dev, linux-kernel@vger.kernel.org, kernel-team@meta.com, sj@kernel.org, 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: <20260728194714.3713735-1-gourry@gourry.net> <20260728194714.3713735-2-gourry@gourry.net> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260728194714.3713735-2-gourry@gourry.net> X-Rspam-User: X-Rspamd-Server: rspam11 X-Rspamd-Queue-Id: 92CCAA000A X-Stat-Signature: mb71n7wr6ais8oiywrz4znq5ny4mcirf X-HE-Tag: 1786023500-275916 X-HE-Meta: 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 Ifn3GeO8 5Th2dQzEF8D0Hx3Br+YXz1ufrG/UN4WPfZPFm0uAin5QrmF+rfRJodQwYKoQs3ou0XQ+gKmxt1jZkCEJLVbu3jAHwP5LICF3zj4Uyuq4PAAkJNK96/gY4iR9qm/kwDww1YXQieLj1mCV4kbyEFuszmfC/332Ic/J8sQSk97u7BWvyy7RouFlA/TmZVWiGt5URpGKvrtuQjj8i+XxC/zrbhdJTqVGkUnsdFriYPOItPrRW+3amaha5RBMvz59SSWXGQmxTweSnH/RmBNPzzZ6F4tNhpkYe0XxSxgw1PBIaZ3Pr1CFwYlnMoZKE98euELwf25LGi2fYCUrKgkicnmglpOYBaH9mHWhvttfjRUoG0UDgUm2I4KXPhyRMJuWcsIivd+VNrSEM/KkZhX/xu/3nI/661uIozCrsqBac3UomaMdloEZgnga+JO5zN180sK281rCgo4PaWrwmxlw= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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) > --- > mm/damon/ops-common.c | 3 ++- > 1 file changed, 2 insertions(+), 1 deletion(-) > > diff --git a/mm/damon/ops-common.c b/mm/damon/ops-common.c > index d7d7f100389b..d8bca7355b4f 100644 > --- a/mm/damon/ops-common.c > +++ b/mm/damon/ops-common.c > @@ -32,7 +32,8 @@ struct folio *damon_get_folio(unsigned long pfn) > folio = page_folio(page); > if (!folio_try_get(folio)) > return NULL; > - if (unlikely(page_folio(page) != folio) || !folio_test_lru(folio)) { > + if (unlikely(page_folio(page) != folio) || !folio_test_lru(folio) || > + folio_is_zone_device(folio)) { > folio_put(folio); > folio = NULL; > } > -- > 2.55.0 > -- Cheers, Lorenzo