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Wed, 23 Sep 2026 08:43:18 +0000 X-Mizu-Trace-ID: c8a1201785675537 X-Migadu-Flow: FLOW_OUT From: Lance Yang To: ljs@kernel.org Cc: akpm@linux-foundation.org, david@kernel.org, ziy@nvidia.com, baolin.wang@linux.alibaba.com, liam@infradead.org, nico.pache@linux.dev, ryan.roberts@arm.com, dev.jain@arm.com, baohua@kernel.org, lance.yang@linux.dev, usama.arif@linux.dev, kas@kernel.org, guoren@kernel.org, bcain@kernel.org, geert@linux-m68k.org, dinguyen@kernel.org, schuster.simon@siemens-energy.com, jonas@southpole.se, stefan.kristiansson@saunalahti.fi, shorne@gmail.com, dalias@libc.org, glaubitz@physik.fu-berlin.de, pjw@kernel.org, palmer@dabbelt.com, aou@eecs.berkeley.edu, alex@ghiti.fr, linux@armlinux.org.uk, vgupta@kernel.org, monstr@monstr.eu, chris@zankel.net, jcmvbkbc@gmail.com, will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, davem@davemloft.net, andreas@gaisler.com, richard.henderson@linaro.org, mattst88@gmail.com, linmag7@gmail.com, catalin.marinas@arm.com, mark.rutland@arm.com, chenhuacai@kernel.org, kernel@xen0n.name, tsbogend@alpha.franken.de, James.Bottomley@HansenPartnership.com, deller@gmx.de, maddy@linux.ibm.com, mpe@ellerman.id.au, chleroy@kernel.org, hca@linux.ibm.com, gor@linux.ibm.com, agordeev@linux.ibm.com, borntraeger@linux.ibm.com, svens@linux.ibm.com, richard@nod.at, anton.ivanov@cambridgegreys.com, johannes@sipsolutions.net, tglx@kernel.org, mingo@redhat.com, bp@alien8.de, dave.hansen@linux.intel.com, x86@kernel.org, hpa@zytor.com, arnd@arndb.de, vbabka@kernel.org, rppt@kernel.org, surenb@google.com, mhocko@suse.com, jgg@ziepe.ca, jhubbard@nvidia.com, peterx@redhat.com, ysato@users.sourceforge.jp, shakeel.butt@linux.dev, corbet@lwn.net, rdunlap@infradead.org, linux-mm@kvack.org, linux-kernel@vger.kernel.org, linux-csky@vger.kernel.org, linux-hexagon@vger.kernel.org, linux-m68k@lists.linux-m68k.org, linux-openrisc@vger.kernel.org, linux-sh@vger.kernel.org, linux-riscv@lists.infradead.org, linux-arm-kernel@lists.infradead.org, linux-snps-arc@lists.infradead.org, linux-arch@vger.kernel.org, sparclinux@vger.kernel.org, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, linux-s390@vger.kernel.org, linux-um@lists.infradead.org, hughd@google.com, qi.zheng@linux.dev, linux-doc@vger.kernel.org Subject: Re: [PATCH v4 05/12] mm: enable MMU_GATHER_RCU_TABLE_FREE for arc, microblaze, xtensa Date: Wed, 23 Sep 2026 16:43:11 +0800 Message-ID: <20260923084311.15570-1-lance.yang@linux.dev> X-Mailer: git-send-email 2.49.0 In-Reply-To: <20260922-rcu-pagetable-freeing-v4-5-fe1ad1f1e303@kernel.org> References: <20260922-rcu-pagetable-freeing-v4-5-fe1ad1f1e303@kernel.org> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit X-Stat-Signature: q6qeak1375kgppqwmknb969de3pq59ji X-Rspamd-Queue-Id: 71932A0005 X-Rspam-User: X-Rspamd-Server: rspam01 X-HE-Tag: 1790153007-905857 X-HE-Meta: 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 XZ8T4zo7 xG2IGK17NjXE+Phkny7gAG58kKLTN1DYZrfPDf8dcvSI+wdA9QJKuS6Wot2RAMQvjeT3xdCeVQVX1vP9nyIpaxhZVvvItJswcW4iMJ2moXBZY7osK5krc5dJ5qxYiOw31aspOIcqSXWPeiPgtO8c6QYUmDlPjKn3dVQS/II8V3DwgdQi51iyrkcxWiH0dMo6r8rtqwzLZsur4WF+FXqP2UDxuaCJN7hQbr5MYvZ+JohY5jpRJYGg55EedqsNpVO7wn8RnNmV+uMIZqgo1Zt3IjsSVAYKAYA7HB+Jo5YdhSWOOFtmRNS3fzpPx64nyQS7VSUGQKxTnqAMNK/2ZQhlUTvWPZR8gQIIkZsFnBPveb4Om0br7uHgQnCQS4sAKIHiQHwpx Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Tue, Sep 22, 2026 at 04:35:36PM +0100, Lorenzo Stoakes (ARM) wrote: >Each of these architectures directly free page tables without routing these >changes through tlb_remove_ptdesc(). > >The use of tlb_remove_ptdesc() is required for >CONFIG_MMU_GATHER_RCU_TABLE_FREE to correctly free page tables under RCU, >so simply update these architectures to use these functions. > >Since none of the architectures share page tables or do anything unusual, >nothing complicated is required here. > >Therefore this is simply a mechanical change - convert __pud_free_tlb(), >__pmd_free_tlb() and __pte_free_tlb() to use tlb_remove_ptdesc() as >required. > >At the point this is in place, all mmu_gather page table freeing is >performed under RCU, and thus MMU_GATHER_RCU_TABLE_FREE is selected for >each architecture. > >Note that CONFIG_MMU_GATHER_RCU_TABLE_FREE is dependent on CONFIG_MMU for >xtensa to reflect the fact that nommu does not implement page table >gathering. > >This forms part of an overall effort to switch every architecture to this >mode. > >Acked-by: Kiryl Shutsemau (Meta) >Signed-off-by: Lorenzo Stoakes (ARM) >--- Right, the old frees already end up in pagetable_dtor_free(). With tlb_remove_ptdesc(), the same cleanup happens after an RCU grace period. Makes sense to me, feel free to add: Acked-by: Lance Yang