From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mta0.migadu.com (out-92.mta0.migadu.com [91.218.175.92]) (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 A5A93382292 for ; Tue, 22 Sep 2026 02:34:23 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.92 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790044465; cv=none; b=MMxI8ld9hdpOYNUmBs3qstfsosbIAcC6pFIYTWa+/Fs9jjOeckWkmWyBi0KzFDooia+kgPAOIvw1uxFqAPQ9yrHkDdDgc0ZZnnJS4PqU48fW1wtQhSFr7RAY88VqxkzI8hevQ3zqjA/ujbkVfB/Y8ln5GgH2r3NxwkFkaVCnp8M= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1790044465; c=relaxed/simple; bh=zmvXUaUh0x7Iq7a1F/nNLaoOJ/x9bsxphrerv34hNIk=; h=Content-Type:Mime-Version:Subject:From:In-Reply-To:Date:Cc: Message-Id:References:To; b=gKOz+L2tgmDAc3cx1ZhUiMOoruGIL+AdJwU2ST5LrzvZJ0FGzhIkC5ShbITB4Z1CYj3dsWyyz2NQGt0099ifsdAS2Z5H66sA/RI2W2/smIfLdlvt68y4ft1EHvQYmEBdGvGW1P9BWyiHVUgsyoXK/0f+rhHQSRaMA/FvcXd9o7Y= 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=Sn3LW23F; arc=none smtp.client-ip=91.218.175.92 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="Sn3LW23F" X-Envelope-To: linux-kernel@vger.kernel.org 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=1790044461; v=1; x=1790649261; b=Sn3LW23FtZNFu8/Mbwet6R4yJXEDRqNlYfe5P2ue0ktck9vAFi6sFm1PSq9NxNM35zNIkNgj mcP7G01BxxKkVQZGzjigwuFHTQ25COq2HXGPT9DhrnaR9faSEGV4CfTCVSNHC4uwko0eVH2FkRK bywolCw9+YANKN8z3CLVdEpI= X-Envelope-To: linux-kernel@vger.kernel.org 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: linux-kernel@vger.kernel.org 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