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bh=sbNemcwZ2jC1Uc7605k/VmRdjgt1QXoYjX9veU4w4sg=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=AmZMQS6IkrbnfBT7rmh94KaapbRI+T4bPXW5CLrWD95W9hDFLpbSOXSkpw3xXQo/Q JYxbCN3+IRkhfvwGbKgCVvGpsM9JFe3wWNJGlkRGMQA8ANaf9+k/k8xlBIbAcWnzPp Gu/m6krdg/kpRdIkq5YulAXt+UH8IoI0/ZzjF63qWP73OIbZYob0g17timLVgd5BY9 qL1SDa2n9NHAzqyNmZU3icOaKvdcHz1y30fvMGOMzo/Hy1SlheQVwh6rxzfGOQ5vtU IaQ5DJGIKcl9/aAKwhsqjbLGlEgU37FyaIqXZWnYggqAyaYAm21ybJnZiBUcAHUWfa UUVl8+gih695A== From: SJ Park To: "Shubhang Kaushik (Ampere)" Cc: SJ Park , Andrew Morton , Fernand Sieber , Shakeel Butt , SeongJae Park , Leonard Foerster , Shubhang Kaushik , "Christoph Lameter (Ampere)" , damon@lists.linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH] mm/damon: align MMU notifier range when clearing PTE young bit Date: Thu, 22 Oct 2026 07:02:31 -0700 Message-ID: <20261022140232.93962-1-sj@kernel.org> X-Mailer: git-send-email 2.47.3 In-Reply-To: <20261021-damon-align-pte-young-notifier-v1-1-d0365ac45b66@gentwo.org> References: X-Archived-By: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Queue-Id: 32E83C0016 X-Stat-Signature: n9gqg9h7by8zt8up76jq5f3wfck3s18m X-Rspamd-Server: rspam01 X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,MAILING_LIST_MULTI,SPF_HELO_PASS,SPF_PASS, USER_AGENT_GIT autolearn=ham autolearn_force=no version=4.0.1 X-HE-Tag: 1792677761-100109 X-HE-Meta: U2FsdGVkX18Htcly+1HLZqbO1Jfsz86ztOzht2rNgnMVQ5MP2jr6mqQRnrceMRdQevAfmrJO+xB6gl5MQuerSfnCjBHlz5Q0FAXVu716ztccamoPETjLCJmDhN2asihH7eSdEncGqEJRSVK3OxENq833r/rL1gNOym8ZJSsDqWI/1mObTsHx4XjUS664X6M6AXEOFrLzoTKaHLNWYPQjPqLDk6HHvYgIWslrQwI+9dh74cR6cNKtVWvAnL2XIWzTN8xZG1Jfa+CZcmwYpaCWhkJsY4az9px+CRyXiagPZNzKzWPYbKQdRRZ9HkpESWHf9IFu3L3Gu3ClQgYhECgDgOsBONZqZ6LPboioyJ6xRJxttTcTtCbk1HwRKM8jBC6alnlZrq9jf8pdrTwK7oD7HYRZAA1lE9i/HOGh7WJ4bcp/QuQfFch4b3CuNq1sA52Inxa0bDtFb3BXxUFYhbBeX+lwfZrAJrdkxAWiLZ6W2hZ5FIJZNoihDntF6NNLIM9803vkhB6AilMrBY/WrUeAtdXiObHTu2gKqUR3CkgTHifS3F/zp6+fXZaxsJQNox0XwaLENIsD80Ygzn9EXKlNj6FGN9dnQ5EQt0XKWANTDWEtfaV/nLndeWNG/lPLLQsUrFmN7Tp7aByCOry7AEMxrH+z25oqxVaibkRBsaTT3imGoTmgADWmNU+uBSV7bbb6lY4ynWj7OtcJmVafmmDnj68sQTy02DPscFauXnc17UDzWEF/d+QM36wVe/8wUdkKbTLHYYJoPfPWVrhMJd4O6T3APO6S0sb7CfQvzBPuH/s5+yiTUhiULto2Tu7/O8TRJDFS6s3OyC/imE9oGLiyZ06tRzU16ZJwAKRvA+L3WWarPesdNCdc78fnbmht+/i56vW9iD+Kery2YyupYBAY8Q27tWfZlXMH+DkD4htl3+R/Jr9e/E3jPfS8aXyNi2HPBikOzF7lS4Nm7KmJyFv C45qNExx bEuN7cnUSVRuPgoeCMOfWntc4ApieIvt2CucIz6EyXlOL31Pdz6aq3ZFVHVuAtpMZnO6c6Psme95MI/RORdxL0daHDRkRgIk+myH7GZNdSb2KN8Io3ScE1Kk3IGszrbEdS3aXsD5HRRAHy5WUlt65XfYp2ptcr/QHLJBe2Qauk0flwsjAaumOKSV/08ya2LOStfi/5AF6qeevvqJZXt6i4pHP5dFy0v48TlBkhz52TTwyirbmGAIyZY5Cm/B9L2QH3Zqnq0+R60bv4oYnzy5n0xpQvd+Wxq7pj8XHG8Xi7FaSRHQxG56kaSXB9JKfVT/3Zi3a 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 Hello Shubhang, On Wed, 21 Oct 2026 23:36:19 -0700 "Shubhang Kaushik (Ampere)" wrote: > DAMON selects a byte-granular sampling address. damon_ptep_mkold() > clears the young bit of the PTE covering that address, but passes the > unaligned range [addr, addr + PAGE_SIZE) to MMU notifiers. > > For an unaligned address, that range extends into the following page. > KVM ages every guest page intersecting the notifier range, so it can age > a secondary mapping for the following page although DAMON cleared only > the sampled page's primary PTE. > > Align the address before both the primary PTE operation and the > MMU notifier call so that they cover the same page. Thank you for finding and fixing this! > > Fixes: 3f49584b262c ("mm/damon: implement primitives for the virtual memory address spaces") I once thought if we need to Cc: stable@. Because this is only for monitoring accruacy improvement and DAMON is only beest-effort, I think we don't need to. > Signed-off-by: Shubhang Kaushik (Ampere) Reviewed-by: SJ Park I applied this patch to damon/next [1] tree. We are now in the middle of the merge window. It may better to focus on making mm.git changes pulled into the mainline, rather than adding more changes that are not really urgent. I understand this series is not really urgent. Hence, Andrew might not add this patch until next -rc1 release. In the case, I will request adding this to mm.git after next -rc1 release. So, no action from your side is needed for now. Let me know if you think this is really urgent. [1] https://origin.kernel.org/doc/html/latest/mm/damon/maintainer-profile.html#scm-trees Thanks, SJ [...]