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Wed, 31 Dec 2025 01:42:43 -0800 (PST) Date: Wed, 31 Dec 2025 09:42:43 +0000 From: Wei Yang To: Qi Zheng Cc: will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, dev.jain@arm.com, akpm@linux-foundation.org, david@kernel.org, ioworker0@gmail.com, linmag7@gmail.com, linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-alpha@vger.kernel.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, Qi Zheng Subject: Re: [PATCH v3 7/7] mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE Message-ID: <20251231094243.zmjs7kgflm7q6k73@master> Reply-To: Wei Yang References: MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: NeoMutt/20170113 (1.7.2) X-Rspamd-Queue-Id: B7BBD140007 X-Stat-Signature: z7cd7kjy8oe1jze6a7x5ac766uan7394 X-Rspam-User: X-Rspamd-Server: rspam06 X-HE-Tag: 1767174165-178625 X-HE-Meta: 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 sJwUxi0R 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 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On Wed, Dec 17, 2025 at 05:45:48PM +0800, Qi Zheng wrote: >From: Qi Zheng > >The PT_RECLAIM can work on all architectures that support >MMU_GATHER_RCU_TABLE_FREE, so make PT_RECLAIM depends on >MMU_GATHER_RCU_TABLE_FREE. > >BTW, change PT_RECLAIM to be enabled by default, since nobody should want >to turn it off. > >Signed-off-by: Qi Zheng >--- > arch/x86/Kconfig | 1 - > mm/Kconfig | 9 ++------- > 2 files changed, 2 insertions(+), 8 deletions(-) > >diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig >index 80527299f859a..0d22da56a71b0 100644 >--- a/arch/x86/Kconfig >+++ b/arch/x86/Kconfig >@@ -331,7 +331,6 @@ config X86 > select FUNCTION_ALIGNMENT_4B > imply IMA_SECURE_AND_OR_TRUSTED_BOOT if EFI > select HAVE_DYNAMIC_FTRACE_NO_PATCHABLE >- select ARCH_SUPPORTS_PT_RECLAIM if X86_64 > select ARCH_SUPPORTS_SCHED_SMT if SMP > select SCHED_SMT if SMP > select ARCH_SUPPORTS_SCHED_CLUSTER if SMP >diff --git a/mm/Kconfig b/mm/Kconfig >index bd0ea5454af82..fc00b429b7129 100644 >--- a/mm/Kconfig >+++ b/mm/Kconfig >@@ -1447,14 +1447,9 @@ config ARCH_HAS_USER_SHADOW_STACK > The architecture has hardware support for userspace shadow call > stacks (eg, x86 CET, arm64 GCS or RISC-V Zicfiss). > >-config ARCH_SUPPORTS_PT_RECLAIM >- def_bool n >- > config PT_RECLAIM >- bool "reclaim empty user page table pages" >- default y >- depends on ARCH_SUPPORTS_PT_RECLAIM && MMU && SMP >- select MMU_GATHER_RCU_TABLE_FREE >+ def_bool y >+ depends on MMU_GATHER_RCU_TABLE_FREE > help > Try to reclaim empty user page table pages in paths other than munmap > and exit_mmap path. Hi, Qi I am new to PT_RECLAIM, when reading related code I got one question. Before this patch, we could have this config combination: CONFIG_MMU_GATHER_RCU_TABLE_FREE & !CONFIG_PT_RECLAIM This means tlb_remove_table_free() is rcu version while tlb_remove_table_one() is semi rcu version. I am curious could we use rcu version tlb_remove_table_one() for this case? Use rcu version tlb_remove_table_one() if CONFIG_MMU_GATHER_RCU_TABLE_FREE. Is there some limitation here? Thanks in advance for your explanation. -- Wei Yang Help you, Help me