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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> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20260903122128.12264-3-songmuchun@bytedance.com> X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 733A3180008 X-Stat-Signature: nagjkf5b5qkqp41jsym5wrpostg4i8hh X-HE-Tag: 1789995207-915990 X-HE-Meta: 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 D36CC/PN SyEDRp970+Hetp4SsyFm9HV3QsqgNNFKb0WXRal9zeg/136fBXxIFTBtEks5wGs5t4q4lcJBXtnuLlXSvjw/wZROESCtrVfEhyWoJTljPH9zny2T7C9/HzjxWRq91814dthfqOS8TUnaL05vWHEDLanhoxX1c3/WvZMp46b7idQHs34y9uV9c/kooAVm3X2BYnlw8FjoeS3f62l9wDQr37pvLM9dfDiZnwJ5ihBtOJ++zzyo= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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