Since forever, MM code has thrown pte_t * around with no concern for const
safety, or typesafety of any kind. This is confusing. Attempt to address it
by:
1) Making sure pte_get*() helpers can cope with const pte_t * arguments
2) Constifying the pte_offset_map_ro_nolock() return type, which by definition
already pledges that users will not write to it.
These two simple steps were already able to uncover code smell from
khugepaged + do_swap_page().
Separate steps could include introducing pte_offset_map_ro_lock() for more
widespread usage of this.
Benefits of this include less confusion and better type-safety. It could also
futurely aid in efforts such as [0] which may want semantic annotation of these
accesses.
Based on mm-unstable and compile-tested on a handful of architectures.
No functional changes intended.
[CC list editorially trimmed for brevity reasons; apologies if you're not on it]
Link: https://lore.kernel.org/linux-mm/20260526-kpkeys-v8-0-eaaacdacc67c@arm.com/#t [0]
Cc: Catalin Marinas <catalin.marinas@arm.com>
Cc: Will Deacon <will@kernel.org>
Cc: "James E.J. Bottomley" <James.Bottomley@HansenPartnership.com>
Cc: Helge Deller <deller@gmx.de>
Cc: Madhavan Srinivasan <maddy@linux.ibm.com>
Cc: Michael Ellerman <mpe@ellerman.id.au>
Cc: Lorenzo Stoakes <ljs@kernel.org>
Cc: "Liam R. Howlett" <liam@infradead.org>
Cc: Vlastimil Babka <vbabka@kernel.org>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Suren Baghdasaryan <surenb@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: "Matthew Wilcox (Oracle)" <willy@infradead.org>
Cc: Jan Kara <jack@suse.cz>
Cc: Zi Yan <ziy@nvidia.com>
Cc: Baolin Wang <baolin.wang@linux.alibaba.com>
Cc: Nico Pache <npache@redhat.com>
Cc: Ryan Roberts <ryan.roberts@arm.com>
Cc: Dev Jain <dev.jain@arm.com>
Cc: Barry Song <baohua@kernel.org>
Cc: Lance Yang <lance.yang@linux.dev>
Cc: Usama Arif <usama.arif@linux.dev>
Cc: Kevin Brodsky <kevin.brodsky@arm.com>
Cc: Muhammad Usama Anjum <usama.anjum@arm.com>
Cc: linux-arm-kernel@lists.infradead.org
Cc: linux-kernel@vger.kernel.org
Cc: linux-parisc@vger.kernel.org
Cc: linuxppc-dev@lists.ozlabs.org
Cc: linux-mm@kvack.org
Cc: linux-fsdevel@vger.kernel.org
Pedro Falcato (5):
mm: constify generic pte_get*()
mm/arm64: constify pte_get*() and contpte get logic
mm/parisc: constify ptep_get() argument
mm/powerpc/8xx: constify ptep_get() argument
mm: constify the pte_offset_map_ro_nolock() return value
arch/arm64/include/asm/pgtable.h | 10 +++++-----
arch/arm64/mm/contpte.c | 4 ++--
arch/parisc/include/asm/pgtable.h | 2 +-
arch/powerpc/include/asm/nohash/32/pte-8xx.h | 2 +-
arch/powerpc/mm/pgtable.c | 2 +-
include/linux/mm.h | 4 ++--
include/linux/pgtable.h | 8 ++++----
mm/filemap.c | 2 +-
mm/khugepaged.c | 2 +-
mm/pgtable-generic.c | 4 ++--
10 files changed, 20 insertions(+), 20 deletions(-)
--
2.55.0