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h=Date:From:To:Cc:Subject:In-Reply-To:References; b=i+e75T3QIFabgdq4302+e/kAAWTtzWgtO+55pSIvME9tAcEFC9IdLKuwSXWkr3ev2 mKtF8FGkjcZ9gFMt02ZfCXsxE1v+7eSbDFWoAI7EGYwYkkXR0L8ovgyp8ulCCWd52Q uGw5lCOdCAr40/87QDQuNJc6zE5LfRktXgWm0f1M= Date: Wed, 2 Sep 2026 19:34:38 -0700 From: Andrew Morton To: Kaitao Cheng Cc: David Hildenbrand , Zi Yan , Matthew Brost , Joshua Hahn , Rakie Kim , Byungchul Park , Gregory Price , Ying Huang , Alistair Popple , Naoya Horiguchi , Mel Gorman , Andi Kleen , Muchun Song , Jun'ichi Nomura , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Kaitao Cheng Subject: Re: [PATCH] migrate: Skip hwpoisoned hugetlb folios during migration Message-Id: <20260902193438.232552868db3af5d54ae3fa1@linux-foundation.org> In-Reply-To: <20260701105544.97059-1-kaitao.cheng@linux.dev> References: <20260701105544.97059-1-kaitao.cheng@linux.dev> X-Mailer: Sylpheed 3.8.0beta1 (GTK+ 2.24.33; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam10 X-Rspamd-Queue-Id: 97AEF40003 X-Stat-Signature: p4qu3phmcku5fefujm38trhh4hmfjq8r X-HE-Tag: 1788402880-295182 X-HE-Meta: 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 loLOLSSX 8yVt3r18lAXlszRVP0ypAC+BGmfvKqEjPfcgFvdLRvOw/XEas5vRINi0+uhfUWzbVdz4o3YUHmq8nXyWTUnqiCfsrnzEz/KuRrQmEihft2AmmySucbd54Dy/gVjoBEInzO9DyMZHVtIjNdajL6cQ1mNhLRuGvmH4u4oO5Q3TKYqAsOf7LFEpmG1tJsDFEKI3srblrvD1wcXt69s5kDgm//oRiuvow28/Sp8f7nWXI4ldGAZ5lvYd4FObRF3QPSn0H22HMmHq6QCqPevjywaWw2krwfNrFtcFI1gXenHCFoecQob/JLLxNCRtDbl+ojFDSXhJgcuO1C3erdZpGqH7k3hxol+tQU2Rh6J+mWt96mtrEiMGQ6GlBstVED6KCpzl06TTd Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, 1 Jul 2026 18:55:44 +0800 Kaitao Cheng wrote: > Date: Wed, 1 Jul 2026 18:55:44 +0800 Well. > Hugetlb migration does not check whether the source folio contains > hwpoisoned memory before trying to move it. After the folio is unmapped, > the move path can reach hugetlbfs_migrate_folio() and then > migrate_huge_page_move_mapping(), which copies the source folio into the > new folio. > > That copy uses folio_mc_copy(), so architectures with recoverable > machine-check copy support can fail the copy with -EHWPOISON. However, > there is no reason to attempt the move once the source folio is already > known to contain poisoned memory. Architectures without such copy_mc > support also fall back to a normal copy, which can consume the poison. > > Check folio_contain_hwpoisoned_page() after locking the source hugetlb > folio and fail the migration with -EHWPOISON before unmapping or copying > it. This covers both a hwpoisoned hugetlb head folio and large folios > that only have the has_hwpoisoned summary flag set. As always: please provide a description of the userspace-visible runtime effects of the bug. Even better if you can present a reproducer. > Fixes: 290408d4a250 ("hugetlb: hugepage migration core") Oct, 2010. So I'm assuming this isn't super-urgent. otoh, now it's out there and known about, perhaps Bad Guys can find a way of triggering this, so the urgency becomes higher. Anyway, please consider the Sashiko report (https://sashiko.dev/#/patchset/20260701105544.97059-1-kaitao.cheng@linux.dev) then update the changelog with the above info. Decide whether we should cc:stable (and describe why) then resend? Thanks.