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bh=BRu+bhG7aKPiwT5vuH3zvlt7PlvdsDOhL/vNEPHmmuE=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=bZE5qae5+56oO0S3uNA4ZnaxllNJL7xt1NU0E09fQ779TxsZvP3TNcLz3cnjE+9yK aPal0ieAg0R7/f/NZT22vH0T1f8E7ieCwBTMhNTpGz/7JKySJSfrYj3blLLbOsbd5J JP0rBHMBYdhLeAFN9ToEtIptslmqlwFr3u/d4WVI= 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 2/6] mm/rmap: use huge_ptep_get() in try_to_unmap_one() Date: Fri, 3 Jul 2026 11:41:55 +0000 Message-ID: <20260703114202.365553-3-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: 7659C80008 X-Stat-Signature: g15t6aye1sp9ngocequ5ykrh4h4qk1sq X-Rspam-User: X-HE-Tag: 1783078966-943376 X-HE-Meta: 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 BDZvGksE VdMFOjJDDvHdX+CnZsQXbk1spALPN5wvQabpBB7U/htUA1N6UbF4m/hm017hcIqvJQ+uT+RhCuLpntUnC4Bxo0jKgFAOzcJrZydfcK/p6rp7notuHVf4ll6eZfH9HsGEl4+cCrkWJWJPgRKXewnAl1jFZjSS8JQB99ooF2LJ4n4xnbKZizB5jQHfD1t8cdlWdmv8ItgcRJxQsw3CQ4u3FnUX1f7Q8lzO4QbzetYHfkZUAQtjXSZno9k8kleGEZU43jAEsy3IP3lkOV+JGZzrHcc4Tdf1gOS60XB7Ma+I19QuwXvDWgFAvJAgy7OPSMhzkI4Nch2cids6PS3EPc/TOU/a5+sRBXKNLseaN6EwkzYHHA3v97MubZBIxW3qVQsbqxGyWlQ0TGYPE+Z0= 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 Reported-by: David Hildenbrand Signed-off-by: Dev Jain --- include/linux/hugetlb.h | 2 ++ mm/rmap.c | 16 ++++++++++------ 2 files changed, 12 insertions(+), 6 deletions(-) diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h index 2abaf99321e90..6996d02acf171 100644 --- a/include/linux/hugetlb.h +++ b/include/linux/hugetlb.h @@ -1261,6 +1261,8 @@ 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..03737daa348c0 100644 --- a/mm/rmap.c +++ b/mm/rmap.c @@ -2095,14 +2095,19 @@ 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 { + 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); @@ -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