From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta1.migadu.com (out-58.mta1.migadu.com [95.215.58.58]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id CCB1A3955E8 for ; Tue, 22 Sep 2026 02:34:15 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.58 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790044458; cv=none; b=CqjYbfVaOZW/p1Zrgm+J8V4TeSlz2DE4v8637Yi+oaUBAHpPWeblAF3d9m+EnDGWS0iwihah/Dn5/6S0iL/KN5u43Db3quStoGCu0t3fjzMga/ligsVUAljf60SsRp33SPaAtF6KSwVE+GqOthmGNSpjFnMD9IPeVpkIetWo850= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790044458; c=relaxed/simple; bh=zmvXUaUh0x7Iq7a1F/nNLaoOJ/x9bsxphrerv34hNIk=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=Wri8oZouERn/wHZVE3vxVgxIZtECBW7Nn2CsuFvLvYyAubf4aA7vUfyVG2rHkcZzZHVGuNIevW9BwsEYq5gaL9OZXlRbvNeTsM5nHB45ghsNXHN8egdzPAHxaTGji296so8dOqY3YWdsaR3HFP35gglvBi5N8gwacHDzdJGtOWA= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=IQDyPBvy; arc=none smtp.client-ip=95.215.58.58 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) header.d=linux.dev header.i=@linux.dev header.b="IQDyPBvy" X-Envelope-To: nvdimm@lists.linux.dev DKIM-Signature: a=rsa-sha256; bh=zmvXUaUh0x7Iq7a1F/nNLaoOJ/x9bsxphrerv34hNIk=; c=simple/simple; d=linux.dev; h=from:to:subject:date:message-id:mime-version:content-type; s=key1; t=1790044453; v=1; x=1790649253; b=IQDyPBvytySjDtCrm0L/kZS6IT9oghsQWxh6du6fIYDq/Vs2yd5ecuSKT8bRupknQYcDeszY RsEseuz9+szDTReT2pIAcA2IgIbVqlFTF+Mx80+zcO0A9HjbVmEQJYtTKxQsEA2iFK2K0J5nQFA uUofquzRY22nEVeQaGHLX3DI= X-Envelope-To: nvdimm@lists.linux.dev Received: by mta12.migadu.com with ESMTPS id 8af55bfa8c8b6846; Tue, 22 Sep 2026 02:34:11 +0000 X-Mizu-Trace-ID: 8af55bfa8c8b6846 X-Migadu-Flow: FLOW_OUT Content-Type: text/plain; charset=us-ascii Precedence: bulk X-Mailing-List: nvdimm@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: Mime-Version: 1.0 (Mac OS X Mail 16.0 \(3864.700.51.1.1\)) Subject: Re: [PATCH 2/4] nvdimm/pmem: avoid HWPoison flag updates for clean pages From: Muchun Song In-Reply-To: Date: Tue, 22 Sep 2026 10:33:54 +0800 Cc: Muchun Song , Andrew Morton , Dan Williams , David Hildenbrand , linux-mm@kvack.org, nvdimm@lists.linux.dev, linux-kernel@vger.kernel.org, linux-fsdevel@vger.kernel.org, linux-cxl@vger.kernel.org, Vishal Verma , Dave Jiang , Alison Schofield , Mike Rapoport , Oscar Salvador , Ira Weiny , Jan Kara , Matthew Wilcox , Lorenzo Stoakes , Vlastimil Babka , Michal Hocko , Qi Zheng Content-Transfer-Encoding: quoted-printable Message-Id: References: <20260903122128.12264-1-songmuchun@bytedance.com> <20260903122128.12264-3-songmuchun@bytedance.com> To: "Oscar Salvador (SUSE)" X-Mailer: Apple Mail (2.3864.700.51.1.1) > On Sep 21, 2026, at 20:53, Oscar Salvador (SUSE) = wrote: >=20 > On Thu, Sep 03, 2026 at 08:21:25PM +0800, Muchun Song wrote: >> pmem_mkpage_present() is called after persistent-memory poison has = been >> cleared. It only needs to clear PG_hwpoison and undo the MCE nospec = state >> for PFNs that are still marked poisoned. >>=20 >> For clean PFNs, test_and_clear_pmem_poison() has no semantic effect, = but it >> still performs an atomic clear operation against struct page flags. = That is >> unnecessary today and conflicts with the FS-DAX vmemmap optimization = added >> later in the series, where clean PFNs may be backed by shared = read-only >> metadata. >>=20 >> Check PageHWPoison() first so only poisoned PFNs update the page = state. >> Poison recovery keeps the same behavior, while clean PFNs no longer = require >> writable per-PFN metadata. >>=20 >> Signed-off-by: Muchun Song >=20 > Then change itself looks good to me, so >=20 > Reviewed-by: Oscar Salvador Thanks for your review. >=20 > but any reason not to hide the PageHWPoison check within = test_and_clear_pmem_poison()? I indeed hadn't considered this point before. But now I find it unnecessary, because a patch [1] has already removed = test_and_clear_pmem_poison(). [1] = https://lore.kernel.org/all/20260903053535.17611-3-kaitao.cheng@linux.dev/= Thanks, Muchun >=20 >=20 >=20 > --=20 > Oscar Salvador > SUSE Labs