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bh=QtQ8GPWloMli0RbtDXW5k6ZOS1ivmXc5LVDMq/8ZE0s=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=VaLjxRt3/7/p0anZpXqR8+DAL6bdCNHL3CUiUSzwJtBPmWo0qYBn1WDY7pWuXqFjq monTMitTvtDfW8B6chmLjY8d3MAnHyUbwQQ7tVbf2qGbaIDhJWU8jioydOr+eHztTW X7Rif88PZSY7xHy3jhDuCDhfJBZtdzD21Ro+O/BM= From: Dev Jain To: muchun.song@linux.dev, osalvador@suse.de, akpm@linux-foundation.org, ljs@kernel.org, david@kernel.org, liam@infradead.org Cc: Dev Jain , riel@surriel.com, vbabka@kernel.org, harry@kernel.org, jannh@google.com, lance.yang@linux.dev, kas@kernel.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, rcampbell@nvidia.com, apopple@nvidia.com, ziy@nvidia.com, matthew.brost@intel.com, joshua.hahnjy@gmail.com, rakie.kim@sk.com, byungchul@sk.com, gourry@gourry.net, ying.huang@linux.alibaba.com, mel@csn.ul.ie, nao.horiguchi@gmail.com, ak@linux.intel.com, j-nomura@ce.jp.nec.com, pfalcato@suse.de, dave.hansen@intel.com, tglx@kernel.org, jpoimboe@kernel.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH 1/5] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Thu, 25 Jun 2026 11:29:50 +0000 Message-ID: <20260625112955.3254283-2-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260625112955.3254283-1-dev.jain@arm.com> References: <20260625112955.3254283-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspam-User: X-Rspamd-Server: rspam08 X-Rspamd-Queue-Id: 0AC8612000F X-Stat-Signature: 3mpp4cffhufoqpmg4887hx8aaboxek3o X-HE-Tag: 1782387020-367158 X-HE-Meta: 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 donft9xI 1Va4qh3cY63wZ+kw7Y6FhK38vPTnfemguxy3JYfc8Usrmtr7T355vlJoRlZr6BQMhO8/v3TykIIgEGNLpXV+/aAkF4125eglR4g9W1uA58xd/pf40nZ+wO+UFX1iqYjydIUDPJvF+pzE13c6LUxBoFiq7qeS2/aHom9KO4DmTY4LFG/kAG+AY8IGav0vWsLCcwcbeQ4KAuBeyfoEtENLAmbuNWbbjImDJjCvXLkrL0eOtuaQRdX1XGFdgH2/RXJUrSK1biuf6pLEZtzspOHuBBNt9O23MvNq9L06k20nrgvxCzXj6VANDAVblqvPLm7VIIDv0KeX5OGb47GOKOAfJd+oy+5tSRy0YE2eHOYjHdAKFW9DnNlZD3z4hSIAlUYoAUqWxM2lII6TVto0= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: try_to_unmap_one() handles hugetlb folios when memory failure needs to replace a poisoned hugetlb mapping with a hwpoison entry. In that case page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in pvmw.pte, but the code reads it with ptep_get(). On arches which provide their own huge_ptep_get() to dereference a huge pte pointer, accessing via ptep_get() would cause pte_pfn(), pte_present() etc to misbehave. It is not clear whether this has a trivially visible effect to userspace. Just use huge_ptep_get() for dereferencing a huge pte pointer. Fixes: c7ab0d2fdc84 ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()") Cc: stable@vger.kernel.org Signed-off-by: Dev Jain --- include/linux/hugetlb.h | 3 +++ mm/rmap.c | 16 ++++++++++------ 2 files changed, 13 insertions(+), 6 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 2abaf99321e90..fdb7bdf7645c5 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1261,6 +1261,9 @@ static inline void hugetlb_count_sub(long l, struct mm_struct *mm) { } +pte_t huge_ptep_get(struct mm_struct *mm, unsigned long addr, + pte_t *ptep); + static inline pte_t huge_ptep_clear_flush(struct vm_area_struct *vma, unsigned long addr, pte_t *ptep) { diff --git a/mm/rmap.c b/mm/rmap.c index 1c77d5dc06e9f..aa8a254efaecc 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2095,11 +2095,16 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, /* Unexpected PMD-mapped THP? */ VM_BUG_ON_FOLIO(!pvmw.pte, folio); - /* - * Handle PFN swap PTEs, such as device-exclusive ones, that - * actually map pages. - */ - pteval = ptep_get(pvmw.pte); + address = pvmw.address; + if (folio_test_hugetlb(folio)) { + pteval = huge_ptep_get(mm, address, pvmw.pte); + } else { + /* + * Handle PFN swap PTEs, such as device-exclusive ones, + * that actually map pages. + */ + pteval = ptep_get(pvmw.pte); + } if (likely(pte_present(pteval))) { pfn = pte_pfn(pteval); } else { @@ -2110,7 +2115,6 @@ static bool try_to_unmap_one(struct folio *folio, struct vm_area_struct *vma, } subpage = folio_page(folio, pfn - folio_pfn(folio)); - address = pvmw.address; anon_exclusive = folio_test_anon(folio) && PageAnonExclusive(subpage); -- 2.43.0