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bh=Ib8HLtVOx0bEstNiQgQ183JVLf7OFocK8ZFR9pqwh+c=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=D00yAIF3PxWlFQ7TUPdyDv/Bkj2YGFHDJzLdp6WtkJ3941gqW0Tlc5PQ77i3EdsD0 wW2iicZugLsxvqgCZ0MbrOxkaRuVF7sbD2nf3gU665s+IsSrXI2sKFC4bK0LQgm5rT TAdYoJBI2FPE0WKowUceZqoHbAKlu0CKJgr37Kho= 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 2/5] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Date: Thu, 25 Jun 2026 11:29:51 +0000 Message-ID: <20260625112955.3254283-3-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-Stat-Signature: riboq3aiuc7yzn8kdrtg1xotqq64p5yx X-Rspamd-Queue-Id: 3D4DB180002 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1782387030-221256 X-HE-Meta: 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 7YFyCD5M c2+OyHwoArm24+Jk/rX58rV/GTnxuQEwaSjICHjpDEeUdBkp2gq9UCw42aCSiRCX5HOpa8k6GxEY/5xA9WyabmmcKPmm1UcWxwkgwPpMvWYpB1ClPxl4bCK2FOkkx5DS+ZT9dcO3ua4kOkp8F+h5qZR0snx6ewcPfPd1whQmZNANirq9jy3tygXSJMTEKNnSwvcXhqYjB1FyOixJFFqy0dYsLM8NO++JMgd+TdAFzkMOJ8OZggV1OtlPvuZArxoHGBoFFqirCU4ft8lXfgG+NEOTF5WpuMdGkc92FTLMY4h9L1aXursaRUl2836M8eVyqQgw64bKeOD6ydf8l7gv+o/w1XHAPVXe3vpJ42dTZS5I8Cm4N1KZTKSUdw8Of2vG6vk41/+SFeWSNg8w= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: try_to_migrate_one() is used by folio migration to replace a present mapping with a migration entry. For hugetlb folios, page_vma_mapped_walk() returns the pte pointer to the hugetlb folio in pvmw.pte, but the code reads the huge pte entry 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. Use huge_ptep_get() to dereference a huge pte pointer. Commit a98a2f0c8ce1 copied the bug from try_to_unmap_one into try_to_migrate_one. Fixes: a98a2f0c8ce1 ("mm/rmap: split migration into its own function") Cc: stable@vger.kernel.org Signed-off-by: Dev Jain --- mm/rmap.c | 16 ++++++++++------ 1 file changed, 10 insertions(+), 6 deletions(-) diff --git a/mm/rmap.c b/mm/rmap.c index aa8a254efaecc..abc3a44baaa3d 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2505,11 +2505,16 @@ static bool try_to_migrate_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 { @@ -2520,7 +2525,6 @@ static bool try_to_migrate_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