From mboxrd@z Thu Jan 1 00:00:00 1970 Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.remote-ip=95.215.58.41 ARC-Seal: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; cv=none; t=1792599170; b=DX85rzwu8f2jBYvzGNMbW7z2LpuIWTkpWclM5VrKYD6TO9tBbkxqlnJMjgy+wu0P1x9x kxSEo7YdCXmn5SJm/djF6ig4TQ/MPFMPe/bQo09Miq0xauolhEQ9QyabkzETtp1aAec2j 1E3p4MsLMexjqPuaiEijgewsn/if3KoHcejT6/KKxz6eBzAe03OmXO5QZUifMmEqJA+Ir qMqHccuBU7i66XyPaFsWFmJvKj1NxQyeQAgEKLjDURKbPSIwka4RgKcEAaJXjdv7D3dNc yAjW4FPKruJdQaS5VO9ShfI4Ht8+aMQn8cI/VH3ZAoz4Zx+bmbGmCyhtBz4ithpZEZg== ARC-Message-Signature: i=1; d=subspace.kernel.org; s=arc20261015; a=rsa-sha256; c=relaxed/relaxed; t=1792599170; h=DMARC-Filter:X-Envelope-To:DKIM-Signature:X-Envelope-To:Received: X-Mizu-Trace-ID:X-Migadu-Flow:Message-ID:Date:MIME-Version:User-Agent: Subject:From:To:Cc:References:Content-Language:In-Reply-To: Content-Type:Content-Transfer-Encoding; bh=fWCXC5NTHDGlDclEH2O75YYSkPzzTN8RMoYOZpRdROY=; b=Yns1/U1Rbx+LJSEbSx6onyCiXXb7URKJGkJGZxCDPB/JvTYNLLGmecxD1N3xSYQiq4hI 7HXwBhM7ZWGGS9tknvLgWTSnxV5J+9RX2ClUCliDNfr6k3ekaDbKg2ckdvMm6pcDm07qf 5tQeD6n4VEoD4e2RXMed4oIdpnrfUG6XDrpZrBNtyLO4eNBbmT7A8WhFD4Nd9OuXU15iM HTUJ9J2RqohzDft+DSVFVq2gG2n49GbSJQE50A0Sd9U/PzGMwBpehg3rXtH+5Py0ROjKp cxXyvWzQ/TTMeEQnB1A+OihlpdF7B30Dlpq9ydUX/qtX8/+8d9dIElti/5BfLOK/LDw== ARC-Authentication-Results: i=1; smtp.subspace.kernel.org; dmarc=pass header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=TBRFoX8I; arc=none smtp.remote-ip=95.215.58.41 Received: from mta1.migadu.com (out-41.mta1.migadu.com [95.215.58.41]) (using TLSv1.3 with cipher TLS_AES_128_GCM_SHA256 (128/128 bits) key-exchange X25519 server-signature ECDSA (prime256v1) server-digest SHA256) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 9FBC660A381F for ; Wed, 21 Oct 2026 16:12:49 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.2 smtp.subspace.kernel.org 9FBC660A381F Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key, unprotected) header.d=linux.dev header.i=@linux.dev header.a=rsa-sha256 header.s=key1 header.b=TBRFoX8I X-Envelope-To: linux-kernel@vger.kernel.org DKIM-Signature: a=rsa-sha256; bh=E7cWh+ZF7GRhp7QeoNOeMiC4IRFKXkLJvJ6m7Tdn1+M=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1792599167; v=1; x=1793203967; b=TBRFoX8IfarmXP3muakvbtwd0Fnn3QkkD4ckj09YU7HdTxPcPh89Uos/XU2JNQ/FoCS4cfxi jY9el39vZ3+nuLjJejOVLV8ZO2aZZ+v2Q7EtY8BM/ASk7vXopV+beNHyiGno7OoNKsaIm/rlV5T e0/6T1gBLeK5+yVvR090buvk= X-Envelope-To: linux-kernel@vger.kernel.org Received: by smtp.migadu.com with ESMTPS id d1bddb8955e5cc6b; Wed, 21 Oct 2026 16:12:47 +0000 X-Mizu-Trace-ID: d1bddb8955e5cc6b X-Migadu-Flow: FLOW_OUT Message-ID: <167a14f0-6a6f-4db1-a34b-905a33d5290d@linux.dev> Date: Thu, 22 Oct 2026 00:12:32 +0800 X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Post: List-Help: List-Subscribe: List-Unsubscribe: List-Owner: Precedence: list MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v2] mm/ksm: keep soft-dirty and uffd-wp when merging a page From: Lance Yang To: samarth.colleges@gmail.com Cc: akpm@linux-foundation.org, xu.xin@linux.dev, Kiryl Shutsemau , chengming.zhou@linux.dev, peterx@redhat.com, rppt@kernel.org, "David Hildenbrand (Arm)" , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org References: <20261020055518.36087-1-lance.yang@linux.dev> <3da45e6d-2b46-4fff-9ff3-241f70d68296@kernel.org> <68f17ee7-d272-4475-8a59-645442e2c210@kernel.org> <2329ee64-f9be-4826-a496-65344e9a9c18@linux.dev> Content-Language: en-US In-Reply-To: <2329ee64-f9be-4826-a496-65344e9a9c18@linux.dev> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit Hi Samarth, Could you send a v3 with just the soft-dirty fix, as David suggested? Leave the uffd-wp/RWP bits to me (I'll take a closer look). On 2026/10/21 17:49, Lance Yang wrote: > > > On 2026/10/21 16:55, Kiryl Shutsemau wrote: >> On Wed, Oct 21, 2026 at 10:21:53AM +0200, David Hildenbrand (Arm) wrote: >>>> +1. Did it ever actually work there :) Why not just skip them and >>>> call it a day :D >>> >>> I think QEMU just always sets MADV_MERGABLE and later activates uffd. >>> So that >>> needs some care to not disable them. So let's rather try to get it >>> fixed properly. >>> >>> Can you send out proper patches? Thanks! > > Thanks David! Will take it over next week and get proper patches out :) > >> >> +1. >> >> Lance's direction is right. Unsharing is not an access: do_wp_page() >> already skips the uffd-wp fault on FAULT_FLAG_UNSHARE, and RWP should do >> the same. > > Thanks Kiryl! Will take a close look at that :) > > Cheers, Lance >