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b=iKZ/K1iqB0cnLxYHoQ9uVxCv0b+d4WthJcUEBANL3iO8xDOAY1zdbGmaFlcNBFdFj m6kn2rPrgmUhvS4mRguW4tD9m7jcen5dda5WSkkV0cHEmXhfHUv6eYU3k1xSaNa79Z IXJyky1bTv0gT41CyD7OAkAEUA3rOtRlpcdlcDL/b5LdjB5gyB+HGCMaBWwoyV6fCI +9qQ5vZO5otJptN/vHoJckJUwGwf50A6JCcE9bUOcBSptoHJqtBiMqPxOEHbIUi/X8 vDJsTTqEMZPUFfr7/nUpNevSmO3bP7v9Onm5l/L9O5C8eglRGnAo3D8xeluHKe2ev5 30/GJP2YZRZKg== Date: Thu, 12 Nov 2026 11:54:11 +0000 From: "Lorenzo Stoakes (ARM)" To: "David Hildenbrand (Arm)" Cc: Usama Arif , Andrew Morton , apopple@nvidia.com, byungchul@sk.com, gourry@gourry.net, jannh@google.com, joshua.hahnjy@gmail.com, liam@infradead.org, linux-fsdevel@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, matthew.brost@intel.com, mhocko@suse.com, pfalcato@suse.de, rppt@kernel.org, surenb@google.com, vbabka@kernel.org, ying.huang@linux.alibaba.com, ziy@nvidia.com, kas@kernel.org, hannes@cmpxchg.org, riel@surriel.com, shakeel.butt@linux.dev, kernel-team@meta.com, baolin.wang@linux.alibaba.com, Nico Pache , ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, stable@vger.kernel.org Subject: Re: [PATCH 1/3] mm: don't PTE-batch a swap-in over a hardware-poisoned subpage Message-ID: References: <20261111113904.650722-1-usama.arif@linux.dev> <20261111113904.650722-2-usama.arif@linux.dev> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: X-Stat-Signature: cm38aj3f1sb159t8563do7u6nmgwbpbc X-Rspam-User: X-Spam-Status: No, score=-5.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS autolearn=no autolearn_force=no version=4.0.1 X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 59E3A2000A X-HE-Tag: 1794484461-375366 X-HE-Meta: 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 vg6O9ciA darSNk6jNnaalAKrprZD9fDlxs/xnyokK3TEC8GcUAmTOGyoGRbRBIk1xA2BxxnhDhcD5Vq5nui7w+YMY+ao+Q8nNVdbN9oCbhiV1vZziujMLuVgahYyvyadR6WcKbKVLo0Mv5J7PDmVS0u97vcVTMBPi42ZMwFy+9wiqLBw5ugF/chrcsc8k/mw8ilxE/eckCkceBX1B6L4pBrQDy9EAgtazv3Xae6qkZDGFvKg9PT2mTh/47vuCESoHnoFeBOIuubjBGQDLkf7mwSNiJraEpKFvrLjoMVe0hhoNOtN17Z6Azt6uqzOONN3WtBccL726esm4tOFBdvp1nuQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: X-Spam-Checker-Version: SpamAssassin 4.0.1 (2024-03-26) on aws-us-west-2-korg-listserv-alma10-1 On Thu, Nov 12, 2026 at 09:56:39AM +0100, David Hildenbrand (Arm) wrote: > On 11/11/26 14:18, Lorenzo Stoakes (ARM) wrote: > > Hm, isn't scanning every single page in the folio potentially quite costly > > here? I thought the point of batching was to improve performance overall? > > Yeah, we don't really want another helper to check for hwpoison. > > If we race with concurrent hwpoison, bad luck. The slapped on memory-failure > code is full of races. That needs a proper long-term solution, not more pain to > core-mm. Yeah exactly. See Usama's reply - it really does narrow into a weird edge case. Scan there if you want to scan at all. Otherwise tough luck yes. > > So let's please try reusing existing helpers that test the large-folio bit. Yes please! -- Cheers, Lorenzo