From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=100.103.45.18 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1794585669; b=Rez374J6+kn1xJTgoBsZbsGF+wM9gpPl14BaIboeltkPYfi9p5k0mLoBZx3LqOZv58jE 2Tcghthig6yHRZFsCJ2zMpo3uC+S9B5jcQAEIC5SuSucaOzUJEiCmZqA1kieBw2m4i0lX 7n5Qt6WaU5LCv648vovL3RrsHzHULrExJ9jczGth69x6sO8uPM3OJKnodn0GAeTnZN4G1 epcHIJ8yrClVtuyHceO8c2H5/P0KFdAfl6IXhm71CL2KTPK1d4K28P/Zfga3BUnGEZ3Cu xWcqIx4TCTovYapMWmCalOP4V4tHrEyx1pnYHwzplSqJ4d2wGeZpu2FxSgacyh865uQ== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1794585669; h=Received:DKIM-Signature:From:To:Cc:Subject:Date:Message-ID:X-Mailer: In-Reply-To:References:User-Agent:X-stable:X-Patchwork-Hint: MIME-Version:Content-Transfer-Encoding; bh=4HvcEf3jn2+1iz5K0uGWg/RynuxiPaiAbCy47u3PV/4=; b=i1SyDcTR7okaooD5bOHEPXASb5nTwEqlS5RKlrT8WZmdF3tjJ1M9jLj1IepxQYE5gggm IxszzFpCcpJQoqI2t1DuRoDJmuXEgV1lgbNWogbalTF/bjArNJ3yImMnDnH5rOvwbspJu JrZtNHOKNrgMyssdomzrtyPjTCGJjJQKoQXyVMsuhGiWUuxEHlmlP7fWTqZ/1/PwWKZrt bE+jIrPtW5J+97HXWe83BlVcPzV68q70Pv2hg4dFIo5LHZjDZyqQu+pjdTrOSsugnii4q G3f++jbEyv3bEgZXXR2ROchQgm6pSpazjPEwKfwCvAyYv1efPLGRI/P5ACIHNi1Lveg== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dkim=pass header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=dEhme36s; arc=none smtp.remote-ip=100.103.45.18 Received: from smtp.kernel.org (quasi.space.kernel.org [100.103.45.18]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature ECDSA (prime256v1)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5D64E606B2DB; Fri, 13 Nov 2026 16:01:09 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linuxfoundation.org header.i=@linuxfoundation.org header.a=rsa-sha256 header.s=korg header.b=dEhme36s Received: by smtp.kernel.org (Postfix) with ESMTPSA id 0E14A1F000C4; Fri, 13 Nov 2026 16:01:09 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linuxfoundation.org; s=korg; t=1794585669; bh=4HvcEf3jn2+1iz5K0uGWg/RynuxiPaiAbCy47u3PV/4=; h=From:To:Cc:Subject:Date:In-Reply-To:References; b=dEhme36sok4nAkQQmKqPUSVgCuVNmbAvcvP9Wh/M2dXbfruoqTOwBY/c39sBZfxcF 0lV7i4OWVE3TDIFnNZkhn3NjS2e22wdXv9BynvIPjZgMh8GVYBN9I6MEC1kNUdABRu sOGszjSVvCD1IMzZ/ZTfhiSYlmxjeqnTT9U3XIyQ= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Samarth Narang , Andrew Morton , Lance Yang , "David Hildenbrand (Arm)" , Xu Xin , Chengming Zhou , Peter Xu , Kiryl Shutsemau , Mike Rapoport , Sasha Levin Subject: [PATCH 7.3 230/507] mm/ksm: keep soft-dirty when merging a page Date: Fri, 13 Nov 2026 10:48:54 -0500 Message-ID: <20261113153802.293545327@linuxfoundation.org> X-Mailer: git-send-email 2.56.0 In-Reply-To: <20261113153753.358973689@linuxfoundation.org> References: <20261113153753.358973689@linuxfoundation.org> User-Agent: quilt/0.69 X-stable: review X-Patchwork-Hint: ignore X-Mailing-List: patches@lists.linux.dev List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 Content-Transfer-Encoding: 8bit 7.3-stable review patch. If anyone has any objections, please let me know. ------------------ From: Samarth Narang [ Upstream commit 2efc6332f18bfd848f74f3d5ba45b31450601faa ] 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. Link: https://lore.kernel.org/20261021182157.1873726-1-samarth.colleges@gmail.com Fixes: 0f8975ec4db2 ("mm: soft-dirty bits for user memory changes tracking") Signed-off-by: Samarth Narang Signed-off-by: Andrew Morton Reviewed-by: Lance Yang Acked-by: David Hildenbrand (Arm) Assisted-by: LLM Cc: Xu Xin Cc: Chengming Zhou Cc: Peter Xu Cc: Kiryl Shutsemau Cc: Mike Rapoport Cc: Signed-off-by: Sasha Levin --- mm/ksm.c | 4 ++++ 1 file changed, 4 insertions(+) diff --git a/mm/ksm.c b/mm/ksm.c index fe42c17490b89..b1f361983e553 100644 --- a/mm/ksm.c +++ b/mm/ksm.c @@ -1462,6 +1462,10 @@ static int replace_page(struct vm_area_struct *vma, struct page *page, dec_mm_counter(mm, MM_ANONPAGES); } + /* Preserve soft-dirty when replacing the page. */ + if (pte_soft_dirty(orig_pte)) + newpte = pte_mksoft_dirty(newpte); + flush_cache_page(vma, addr, pte_pfn(ptep_get(ptep))); /* * No need to notify as we are replacing a read only page with another -- 2.53.0