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f5407e9b69
Patch series "Fix incorrect access of hugetlb pte entries", v3.
There are various places which use ptep_get() to get the pte entry
corresponding to a hugetlb folio. Some arches (like s390) have special
handling to compute the pteval, so they provide huge_ptep_get(). Use this
helper consistently.
Additionally, some code paths may provide huge_ptep_get with an unaligned
address. This is a problem on arm64 (I checked other arches and it looks
fine for them), which is fixed in patch 1. The fix is made to be
backport-friendly: the cleaner fix would be to perhaps pass the hstate to
huge_ptep_get() - that is wider churn and we can do that later.
This patch (of 5):
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.
Link: https://lore.kernel.org/20260703114202.365553-1-dev.jain@arm.com
Link: https://lore.kernel.org/20260703114202.365553-3-dev.jain@arm.com
Fixes: c7ab0d2fdc ("mm: convert try_to_unmap_one() to use page_vma_mapped_walk()")
Signed-off-by: Dev Jain <dev.jain@arm.com>
Reported-by: David Hildenbrand <david@kernel.org>
Reviewed-by: Muchun Song <muchun.song@linux.dev>
Acked-by: David Hildenbrand (Arm) <david@kernel.org>
Cc: Alistair Popple <apopple@nvidia.com>
Cc: Andi Kleen <ak@linux.intel.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Byungchul Park <byungchul@sk.com>
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Dave Hansen <dave.hansen@intel.com>
Cc: Gregory Price <gourry@gourry.net>
Cc: Harry Yoo <harry@kernel.org>
Cc: "Huang, Ying" <ying.huang@linux.alibaba.com>
Cc: Jann Horn <jannh@google.com>
Cc: Josh Poimboeuf <jpoimboe@kernel.org>
Cc: Joshua Hahn <joshua.hahnjy@gmail.com>
Cc: Jun'ichi "Nick" Nomura <j-nomura@ce.jp.nec.com>
Cc: Kiryl Shutsemau <kas@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Liam R. Howlett <liam@infradead.org>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: Matthew Brost <matthew.brost@intel.com>
Cc: Mel Gorman <mel@csn.ul.ie>
Cc: Naoya Horiguchi <nao.horiguchi@gmail.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Pedro Falcato <pfalcato@suse.de>
Cc: Rakie Kim <rakie.kim@sk.com>
Cc: Ralph Campbell <rcampbell@nvidia.com>
Cc: Rik van Riel <riel@surriel.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Will Deacon <will@kernel.org>
Cc: Zi Yan <ziy@nvidia.com>
Cc: <stable@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>