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Thu, 22 Oct 2026 00:51:12 +0000 X-Mizu-Trace-ID: 3fa99ff370979236 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: samarth.colleges@gmail.com Cc: akpm@linux-foundation.org, david@kernel.org, xu.xin@linux.dev, chengming.zhou@linux.dev, peterx@redhat.com, kas@kernel.org, rppt@kernel.org, lance.yang@linux.dev, linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH v3] mm/ksm: keep soft-dirty when merging a page Date: Thu, 22 Oct 2026 08:51:02 +0800 Message-ID: <20261022005102.29011-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20261021182157.1873726-1-samarth.colleges@gmail.com> References: <20261021182157.1873726-1-samarth.colleges@gmail.com> X-Archived-By: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam12 X-Rspamd-Queue-Id: 85D3DC0003 X-Stat-Signature: si5fhs7j83w9ic5tmh7sgip99j35mfcw X-Spam-Status: No, score=-13.8 required=3.0 tests=BAYES_00,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-Rspam-User: X-HE-Tag: 1792630274-25541 X-HE-Meta: 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 /nt6tFpy SINmY9A/9U022mEGPWjDC5vLT6A68Dyt/AP2lXBIytgE+s/m9a9B3MxDtVC1268hvsnqsjsgMSxFPzUX+/9c2IXsSCkSkJwiVH95ZBV1V3JvAvimZUIrLKlkjeuIADo7lMyafhEyMH9Zt2y7WbBphOOHUKPTBAW6M1Bp3UpO8nJSdzFZHg7bDtuVAJHqD/79wSUPGHw6OVLHLvzxYlo0tCjW5iMKoaUiIM0+0fvbcUcxFpvhb7R0Va9JNPERteCqCB9umtLQq8Nj8frnb6M6gEiZsvOMc/PpQdCfAXcqZwtAcos6XYJBGM2NMWZSTFj0XPpvFJyKYXuXWz/JFte6/38LbBMCRZPgHOWRovUkuLKr7r0E= 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 Wed, Oct 21, 2026 at 11:21:57AM -0700, Samarth Narang wrote: >replace_page() maps the KSM page with a PTE built from scratch, so the >soft-dirty bit of the PTE it replaces is lost. A page written since >"clear_refs 4" then no longer shows as soft-dirty once it is merged, and >a soft-dirty based dumper treats it as unchanged. > >Copy the soft-dirty bit from the original PTE to the new PTE. > >Fixes: 0f8975ec4db2 ("mm: soft-dirty bits for user memory changes tracking") >Cc: stable@vger.kernel.org >Assisted-by: LLM >Signed-off-by: Samarth Narang >--- LGTM! Reviewed-by: Lance Yang