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b=qA1Aq20xJgjpSoMfhVPELlB3kaMSb4V949hdTJTF7ntA/YDRLPvppPlo71J3iNVEz rWPCZzTejHHH+XB9IiMGiMIVOdrHLg92f88tFmfG7Ee4vaZkHKHJOAzq+fw14Nu3o3 3XyFg2T6izd3Edg2iO6j9aynx/8E5EKvZC7I5BKofd1bGmvairPCUhH9p0rE64TXbh AZHNfuCTQICVlmaoj472l/aJicPGDjbXohpy9QXQzRldQth+W5Xr/j92I3bfizc0/9 jMOW/hMOBwidFSFHMxnmxaY04o9i2lgVgZ7aCLmsvinqdRjXMYgP1qT2fZwJzh2seo M6yCbvZJ5I0bw== Date: Thu, 8 Jan 2026 18:29:19 +0000 From: Will Deacon To: Barry Song <21cnbao@gmail.com> Cc: Weilin Tong , Catalin Marinas , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, Andrew Morton , David Hildenbrand , linux-mm@kvack.org, baolin.wang@linux.alibaba.com Subject: Re: [RFC PATCH] arm64: Kconfig: enable ARCH_WANTS_THP_SWAP for all pagesizes Message-ID: References: <20251226063759.4020782-2-tongweilin@linux.alibaba.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 22F7918000A X-Stat-Signature: ckhjr8j7bbbwsu44omccq64adeo597gp X-Rspam-User: X-HE-Tag: 1767896965-359368 X-HE-Meta: U2FsdGVkX1+xUIseHgBjT3CiG+FdSZuVN71DMOm1fmFy9imjWnAhAYOtm0rd5Bt87NnQfx/FykZ5eIhjKXCWoezmJc/Qvk5LkJRJDgWWa/hvWRcKSZWnhUo7uYngToebLhxbcjEenVA0ZAWl6RiSHvTIkNMhxHoTqiLhuat4a6QK7lieBiR0iwaIG0Viso1ORkCblXUHe2Gp08JNFDHl2EOykxXGNJLLjwXG7xaY4HiE19j0s0qV7CRgYAcn6NVfNazqpx1SDq9ezI0YF+N4hWQ519mWS6YASGIFDVehqn0HeXtXClq/jWMrCSiZpAv24Vj9Wk0Mx1dpH08CLkbJKCYQa2+z9F7gybNVhxx+vb8bjz3h5AJQ+S2UfXjDn/M97a6dE84U9EE9y2gGHlX8qkKV9WA/GZ70UES4UEqHHHb7Rz5KkLgKthZ+ARN88MjQ428wRhqKGy1Z6Law4FhyZ8zSnOA+0sTDFKoiTr76C3yqaWfTDw+5BwLcoNwTWZ758YpvVo2aYkEEdqR5rE8o6EWvimSkJb+9tC9n+kgij73GN7Ocsdo+qiaLmc35pKKUxjuuOdE7I9qbozHNelC6bz/bmEZxn0p3G9irKE8rN1ohWJYX/ONL8kNgZotzlwsmtO64yE893ZfYd5fNaZr6pZcRWsNHLSJRdTKMUUEksAIIHyegeoHBKFCsqWvTLMKw64tS4QwnOiEAFk26oyuefATYI9t2StM7oYId73sd8zubr6LJCidMWjBB+686C0clkoL1qOjCRP3CGtU2uZ4dbMe1iYES3e2AidNJpGsU9CkvGSlWi/W8x5/Wp63/WBOc7hRv+XQF+C6D0vwAOVSN7ccv/weguUGxm3odglQ5DMupBxYLyYINncJsmxP8t1VS7wqUMjoRUjUdVGINPqp4a8hbAJUpL6vPQF+0jD5s9FRyEKhjSh8dXMnDTT61xmSIYrqa1i9VhjJUqd2VBAa Jg7ymlKO 1gPSiyf1h98EJq67m6LjWdihnTo+Ty2o/ofisU1WLFWjc0k8jmUszaiOODV2xpBby2Xg3kh1oIy7ZHjPfIsVX9O1WH5YN5VdnjozjRx4yBCx+jCW0SghPWPUK1kja+2V68WH1jl+VW2ZOF7ZrAxD/SiLF1a+SkZV1AWAlCvcv/K9El4KhC+e4AfVBB5inaPakSXFEvg4lHrM3jOT3jVZOvBUyUz+buSPcoksmlNSlJsllnU3lnF6VTebKBBG74uj9FhofPt/dXd8hohIBXCANJRI+m5C0lO8jKbuuCAUuAyftxrllUl+2ysyYt2tNqUrCGXoGad4TVEDEgQDsNQ49zaHqqOMCiQtPcH59hOw67Was4LYWc6CLVDNbaijSJJHuu8TlD/r29e5so9E= X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Fri, Dec 26, 2025 at 07:52:44PM +1300, Barry Song wrote: > On Fri, Dec 26, 2025 at 7:39 PM Weilin Tong > wrote: > > > > Currently, ARCH_WANTS_THP_SWAP was limited to 4K page size ARM64 kernels, but > > large folios requiring swapping also exist in other page size configurations > > (e.g. 64K). Without this config, large folios in these kernels cannot be swapped > > out. > > > > Here we enable ARCH_WANTS_THP_SWAP for all ARM64 page sizes. > > I no longer recall why this was not enabled for sizes other than > 4 KB in commit d0637c505f8a ("arm64: enable THP_SWAP for arm64"), but > it appears to be fine, and the swap cluster size should also be > more friendly to PMD alignment. You seemed to be worried about I/O latency in your original post: https://lore.kernel.org/all/20220524071403.128644-1-21cnbao@gmail.com/ Will