From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 2318E29B8EF; Mon, 19 Jan 2026 10:20:50 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=10.30.226.201 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768818051; cv=none; b=VYYj2BKXOmYTwLZoJ13mdQkt/Uqwd++jRe8I3QKGBWIsrD4FNx1LT0c7jkIpeHCoHLzu/wWYeULrORJdAedbVR7BDjLBD+vpMVcfuT36Xxh0VfCEe4wSc1UKgiNg3dinkq0pl1sl1LB1z7a/TB8tvOGvnEdyehm2f9Ry6/YjHl4= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1768818051; c=relaxed/simple; bh=O3CZH8Niuk4d+2faxjZDZylA2Qy1X04DLYp5vprOyBE=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=u4akPk7zdtJCNBxAtvaj+BnMtwIr+/CzUUJbJAznYxJTrCumMByqTC3YTOYr81SqQ0+ZGdgo4Y+XPr78ycNFS0HTe5Wvqq4oblZvyMpixKEkc86qWxHgRWZjQwhuDBKQ5TuVtViQkvdd54stfZgi/MeD3G1cqt/x8i51+kTnMaM= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b=UGJywINq; arc=none smtp.client-ip=10.30.226.201 Authentication-Results: smtp.subspace.kernel.org; dkim=pass (2048-bit key) header.d=kernel.org header.i=@kernel.org header.b="UGJywINq" Received: by smtp.kernel.org (Postfix) with ESMTPSA id 9C777C116C6; Mon, 19 Jan 2026 10:20:46 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1768818050; bh=O3CZH8Niuk4d+2faxjZDZylA2Qy1X04DLYp5vprOyBE=; h=Date:Subject:To:Cc:References:From:In-Reply-To:From; b=UGJywINqQlP26oRRuhAQ30+JcvUZC+z/ghQV8udAX6B0OfOCG6e8Ee3Icuh7OauiH brY18ro3p1vlEEGM50AhTaFe1ByWTrAJrlkI+Vc38HMnwRyHBXLkBfwCUD7MKp+y1J wgkXJeBumJzByhtc7X5Nj8HKhbkG5+AfLAmweLY/u06veL1F8Lwy+yUwK+YFJp3deh eklC+rPkPsTDk+n5Ndj2/qMIzz7E5YVB0PVzHle+JUwuGqUOGr+SYadyycXj6/6TRQ gYM1iEnTf1YtwkHa+FFOYCTMh0B0qwRDcQgCJavPQE53rxebxOlIU+X92AH9h5z39s ingEnw2wBQ8eQ== Message-ID: <8e164e8b-1748-4570-822c-b973770e8fb7@kernel.org> Date: Mon, 19 Jan 2026 11:20:44 +0100 Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH v3 7/7] mm: make PT_RECLAIM depends on MMU_GATHER_RCU_TABLE_FREE To: Qi Zheng , will@kernel.org, aneesh.kumar@kernel.org, npiggin@gmail.com, peterz@infradead.org, dev.jain@arm.com, akpm@linux-foundation.org, ioworker0@gmail.com, linmag7@gmail.com Cc: 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 References: From: "David Hildenbrand (Red Hat)" Content-Language: en-US Autocrypt: addr=david@kernel.org; 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charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit On 12/17/25 10:45, 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. Right, and if there is ever a need to, I wonder whether that should be a boottime/runtime toggle instead. So far we haven't heard of any relevant runtime overheads that causes problems. > > 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. Nothing jumped at me. Hopefully we're not missing something important :) Acked-by: David Hildenbrand (Red Hat) -- Cheers David