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bh=h1IY5vXGtS5qm0GLFc9NhQBQjfsdy191rN1Uth+Oiss=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=k2n+xkzcwCyd3J/xSa4zKVaUpOHOy35BxeWEYAFbGOCKUM0tXaNOstPt5Q76BSk3n yjtzVV2etNN40/5idIaXRjsy/phcdoOXCHriXGcjm3ZFmeV1EARux/ZHb42t7GgVAC OzlyxC0kw2XvxGBk6gm4fmcJpkt6Hip6x3aoeeAQ= 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, apopple@nvidia.com, rcampbell@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, ak@linux.intel.com, nao.horiguchi@gmail.com, mel@csn.ul.ie, j-nomura@ce.jp.nec.com, pfalcato@suse.de, tglx@kernel.org, dave.hansen@intel.com, jpoimboe@kernel.org, catalin.marinas@arm.com, will@kernel.org, linux-arm-kernel@lists.infradead.org, ryan.roberts@arm.com, anshuman.khandual@arm.com, stable@vger.kernel.org Subject: [PATCH v3 3/6] mm/rmap: use huge_ptep_get() in try_to_migrate_one() Date: Fri, 3 Jul 2026 11:41:56 +0000 Message-ID: <20260703114202.365553-4-dev.jain@arm.com> X-Mailer: git-send-email 2.43.0 In-Reply-To: <20260703114202.365553-1-dev.jain@arm.com> References: <20260703114202.365553-1-dev.jain@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Rspamd-Server: rspam02 X-Rspamd-Queue-Id: 0291740006 X-Stat-Signature: uppahmkkkxsm3ai8sd3y9erhcj67emuk X-Rspam-User: X-HE-Tag: 1783078974-860880 X-HE-Meta: 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 hnUxFHnJ FieljATGEHfrcNWA8pL0ft5JRcuVF1AnbejOZrGDRg45wTpVyjCt00OzxdLVzJNi8MHRII+R0VastF89hOvOEP2X2PjInY5xST0En1i1RrqnO7k2msNT968+mB2n0Xp/mUfL/xp9J+hB1dOFTLvpuB9n1wNvTxNFXgmFtBT4ByDA2iITdoKSdSy23E8BojaR61ycmEOkdkM7g+s/9qhdVF89gemrFi3qDs4oLkCC0lSxBl54c4tf0+D7GdeQ5VFw9NplpAYl1TCqi2xDUsONUOBV7+4nn61aljsovGiau7F1TXvJ3arwOSs4huOLJ68D0r1ELIojzKes94W2CoRviynBtjC5DGXaHTXkUwoj+aUvDmd6y3Wpbh9zZyb4l4L7jwwpz8eg0xiSvSLI= 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 Acked-by: Muchun Song 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 03737daa348c0..ea4ad5e662f7d 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2505,14 +2505,19 @@ 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 { + pteval = ptep_get(pvmw.pte); + } if (likely(pte_present(pteval))) { pfn = pte_pfn(pteval); } else { + /* + * Handle PFN swap PTEs, such as device-exclusive ones, + * that actually map pages. + */ const softleaf_t entry = softleaf_from_pte(pteval); pfn = softleaf_to_pfn(entry); @@ -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