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Bottomley" , Helge Deller , Madhavan Srinivasan , Michael Ellerman , Lorenzo Stoakes , "Liam R. Howlett" , Vlastimil Babka , Mike Rapoport , Suren Baghdasaryan , Michal Hocko , "Matthew Wilcox (Oracle)" , Jan Kara , Zi Yan , Baolin Wang , Nico Pache , Ryan Roberts , Dev Jain , Barry Song , Lance Yang , Usama Arif , Kevin Brodsky , Muhammad Usama Anjum , linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-mm@kvack.org, linux-fsdevel@vger.kernel.org Subject: [PATCH v2 0/6] mm: add basic PTE const type-safety Date: Mon, 3 Aug 2026 17:43:54 +0100 Message-ID: <20260803164400.531199-1-pfalcato@suse.de> X-Mailer: git-send-email 2.55.0 MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Spamd-Result: default: False [-1.30 / 50.00]; BAYES_HAM(-3.00)[100.00%]; SUSPICIOUS_RECIPS(1.50)[]; NEURAL_HAM_LONG(-1.00)[-1.000]; MID_CONTAINS_FROM(1.00)[]; R_MISSING_CHARSET(0.50)[]; NEURAL_HAM_SHORT(-0.20)[-1.000]; MIME_GOOD(-0.10)[text/plain]; RCVD_COUNT_TWO(0.00)[2]; FREEMAIL_CC(0.00)[suse.de,arm.com,kernel.org,HansenPartnership.com,gmx.de,linux.ibm.com,ellerman.id.au,infradead.org,google.com,suse.com,suse.cz,nvidia.com,linux.alibaba.com,redhat.com,linux.dev,lists.infradead.org,vger.kernel.org,lists.ozlabs.org,kvack.org]; ARC_NA(0.00)[]; RCVD_VIA_SMTP_AUTH(0.00)[]; MIME_TRACE(0.00)[0:+]; TO_DN_SOME(0.00)[]; RCPT_COUNT_TWELVE(0.00)[33]; TO_MATCH_ENVRCPT_ALL(0.00)[]; FROM_HAS_DN(0.00)[]; FROM_EQ_ENVFROM(0.00)[]; URIBL_BLOCKED(0.00)[arm.com:email,kvack.org:email,suse.cz:email,gmx.de:email,ozlabs.org:email,nvidia.com:email,infradead.org:email,alibaba.com:email,suse.com:email,suse.de:mid,imap1.dmz-prg2.suse.org:helo,linux.dev:email,ellerman.id.au:email,hansenpartnership.com:email]; RCVD_TLS_ALL(0.00)[]; DBL_BLOCKED_OPENRESOLVER(0.00)[linux.dev:email,hansenpartnership.com:email,gmx.de:email,suse.com:email,kvack.org:email,arm.com:email,imap1.dmz-prg2.suse.org:helo,ellerman.id.au:email,nvidia.com:email,suse.de:mid,infradead.org:email,alibaba.com:email,ozlabs.org:email]; R_RATELIMIT(0.00)[to_ip_from(RLxu57a9hfgn7tttf5jiwuqe5o)]; DKIM_SIGNED(0.00)[suse.de:s=susede2_rsa,suse.de:s=susede2_ed25519]; FREEMAIL_ENVRCPT(0.00)[gmx.de] X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.9.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20260803_094429_968593_7CA49982 X-CRM114-Status: GOOD ( 13.14 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org 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 Cc: Will Deacon Cc: "James E.J. Bottomley" Cc: Helge Deller Cc: Madhavan Srinivasan Cc: Michael Ellerman Cc: Lorenzo Stoakes Cc: "Liam R. Howlett" Cc: Vlastimil Babka Cc: Mike Rapoport Cc: Suren Baghdasaryan Cc: Michal Hocko Cc: "Matthew Wilcox (Oracle)" Cc: Jan Kara Cc: Zi Yan Cc: Baolin Wang Cc: Nico Pache Cc: Ryan Roberts Cc: Dev Jain Cc: Barry Song Cc: Lance Yang Cc: Usama Arif Cc: Kevin Brodsky Cc: Muhammad Usama Anjum 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 v2: - Small fixups on the arm64 side - Re-order patches in a way such that bisection is preserved - Pick up Helge's patch dropping parisc ptep_get() - Constify s390's ptep_get() as well Helge Deller (1): parisc: Drop own implementations for ptep_get() and ptep_test_and_clear_young() Pedro Falcato (5): mm/arm64: constify pte_get*() and contpte get logic mm/powerpc/8xx: constify ptep_get() argument mm/s390: constify ptep_get() argument mm: constify generic pte_get*() mm: constify the pte_offset_map_ro_nolock() return value arch/arm64/include/asm/pgtable.h | 10 +++++----- arch/arm64/mm/contpte.c | 11 ++++++++--- arch/parisc/include/asm/pgtable.h | 20 -------------------- arch/powerpc/include/asm/nohash/32/pte-8xx.h | 2 +- arch/powerpc/mm/pgtable.c | 2 +- arch/s390/include/asm/pgtable.h | 2 +- include/linux/mm.h | 4 ++-- include/linux/pgtable.h | 8 ++++---- mm/filemap.c | 2 +- mm/khugepaged.c | 2 +- mm/pgtable-generic.c | 4 ++-- 11 files changed, 26 insertions(+), 41 deletions(-) -- 2.55.0