From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-alma10-1.taild15c8.ts.net [100.103.45.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id DB75D3AE1A8; Mon, 21 Sep 2026 12:53:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=100.103.45.18 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789995207; cv=none; b=VIOcG7rRSdVNLxsC7skXuGZOq3OZyotHfNyubrw0yf1oiPoNXo05FfPjYpSEKAEYzu5x4ZkMxFl/C+Q5QOUz54g+Lu86O81jDMK6OZ1bL1b2PpZXkdujXryZGsk/WDDf0gVEtGgJYGAPH3hh+U14p1X/0PkvVGge2lD1bHzbYkw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1789995207; c=relaxed/simple; bh=n9rDEJIzZr104TrF0pw5cDt2owmwZL4ewpRRtqUnaqw=; h=Date:From:To:Cc:Subject:Message-ID:References:MIME-Version: Content-Type:Content-Disposition:In-Reply-To; b=Jh3UceSLlRu0dArrrLhNIstRwFz0KGBywbV5jPv13rMwFoKwtyd96Ah4QY7me4h6d2tE15IMN5mdJ2IUhbRQiVwJLEWgWMxbbEVBwK53btPah1XLwXgOGgjMYP4aAhcqd45T1uwmBCmtSD1vEUaux8gL7Pm+HcgwcARwxZMgcXs= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=dFrt7yys; arc=none smtp.client-ip=100.103.45.18 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="dFrt7yys" Received: by smtp.kernel.org (Postfix) with ESMTPSA id A1A7F1F000FF; Mon, 21 Sep 2026 12:53:21 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=kernel.org; s=k20260515; t=1789995206; bh=2DiedpCEs1UwpptAonzE7XEdXRU4rM/b7fTnTmQH/H8=; h=Date:From:To:Cc:Subject:References:In-Reply-To; b=dFrt7yysP9TttxshusGVo+wqV0Pa58hUk2WG6svLyuxuUeTN6Yk5xP10tOPEsLtEC EnWcSnS+rffkxsidpoYgAsl6IafaBtTVk4Lfi2EZvWpntEjoIZwt+BpcRs866RQvGM /XQuKCjWS1arBOebH7Vat0gne4zFqjsHpp2cCCLZg1d1jfgydoBJgOS4gLJJcttl7a DIMXqEEPogHji5Y9xurwB/+uI5r25AlYut4l3h6Jte/XS+yun1Ul5VICrwIOzJE3wR mqkamTH6tFQM4ZS4Q4nI2U/a7WSgZPXBc64svBSZgtQ1OgMskfW19zi+HobOPEYDVm Hvc/dKRCsJ7FA== Date: Mon, 21 Sep 2026 14:53:18 +0200 From: "Oscar Salvador (SUSE)" To: Muchun Song Cc: 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 , muchun.song@linux.dev Subject: Re: [PATCH 2/4] nvdimm/pmem: avoid HWPoison flag updates for clean pages Message-ID: References: <20260903122128.12264-1-songmuchun@bytedance.com> <20260903122128.12264-3-songmuchun@bytedance.com> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260903122128.12264-3-songmuchun@bytedance.com> 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. > > 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. > > 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. > > Signed-off-by: Muchun Song Then change itself looks good to me, so Reviewed-by: Oscar Salvador but any reason not to hide the PageHWPoison check within test_and_clear_pmem_poison()? -- Oscar Salvador SUSE Labs