From: "Oscar Salvador (SUSE)" <osalvador@kernel.org>
To: Muchun Song <songmuchun@bytedance.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Dan Williams <djbw@kernel.org>,
David Hildenbrand <david@kernel.org>,
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 <vishal.l.verma@intel.com>,
Dave Jiang <dave.jiang@intel.com>,
Alison Schofield <alison.schofield@intel.com>,
Mike Rapoport <rppt@kernel.org>,
Oscar Salvador <osalvador@suse.de>, Ira Weiny <iweiny@kernel.org>,
Jan Kara <jack@suse.cz>, Matthew Wilcox <willy@infradead.org>,
Lorenzo Stoakes <ljs@kernel.org>,
Vlastimil Babka <vbabka@kernel.org>,
Michal Hocko <mhocko@suse.com>, Qi Zheng <qi.zheng@linux.dev>,
muchun.song@linux.dev
Subject: Re: [PATCH 2/4] nvdimm/pmem: avoid HWPoison flag updates for clean pages
Date: Mon, 21 Sep 2026 14:53:18 +0200 [thread overview]
Message-ID: <arEovvqEpquODZ6X@localhost.localdomain> (raw)
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 <songmuchun@bytedance.com>
Then change itself looks good to me, so
Reviewed-by: Oscar Salvador <osalvador@suse.de>
but any reason not to hide the PageHWPoison check within test_and_clear_pmem_poison()?
--
Oscar Salvador
SUSE Labs
next prev parent reply other threads:[~2026-09-21 12:53 UTC|newest]
Thread overview: 17+ messages / expand[flat|nested] mbox.gz Atom feed top
2026-09-03 12:21 [PATCH 0/4] mm: Reduce struct page overhead for FS-DAX pmem Muchun Song
2026-09-03 12:21 ` [PATCH 1/4] mm: generalize vmemmap remap architecture support Muchun Song
2026-09-21 12:25 ` Oscar Salvador (SUSE)
2026-09-03 12:21 ` [PATCH 2/4] nvdimm/pmem: avoid HWPoison flag updates for clean pages Muchun Song
2026-09-03 12:41 ` sashiko-bot
2026-09-21 7:33 ` Gupta, Pankaj
2026-09-21 12:53 ` Oscar Salvador (SUSE) [this message]
2026-09-22 2:33 ` Muchun Song
2026-09-03 12:21 ` [PATCH 3/4] mm: add shared read-only vmemmap support for FS-DAX Muchun Song
2026-09-21 6:42 ` Gupta, Pankaj
2026-09-21 9:33 ` Muchun Song
2026-09-21 11:05 ` Gupta, Pankaj
2026-09-21 13:09 ` Oscar Salvador (SUSE)
2026-09-22 3:17 ` Muchun Song
2026-09-03 12:21 ` [PATCH 4/4] fsdax: materialize pmem vmemmap metadata on faults Muchun Song
2026-09-03 12:53 ` sashiko-bot
2026-09-05 3:26 ` Muchun Song
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