From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-182.mta0.migadu.com (out-182.mta0.migadu.com [91.218.175.182]) (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 CEED61CEADB for ; Wed, 19 Nov 2025 12:16:11 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=91.218.175.182 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763554574; cv=none; b=r8LdxDhaQSkr3pvQCSvguuRH0JSYuhjga22dLTqu+JyXdQsK4x1pijtIKj6ZjTC4k2wqLsQNE8iUHj8G7VWQ1cfS9crdV+4n+C2b1Dx6tlwWRFn70TXjaIHv7hHsj9p7PCBi3eCvWj6azLSJ7boXufuLmSBzdU5uogGvRheaU50= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763554574; c=relaxed/simple; bh=NOfOnn03Q1ZH3fp+giJQ+9zw24c2IS8H6URgJUfWT+A=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=WT23G4emmdIF13v7v2tkba2dZhv77EUchcB+BtGpjJqR+WHNo73IAkbPugDSh6mIFx1wqaSe9g25//mutFwH3QAvXH2u8mgTkoO1OW630mFvzdSOva5ZPesJW6GnLfiUH6vXp/aXkhAQ5lZhEstlvtiWP/HIQ6rEIlErUbxD/ic= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=AVtUPokb; arc=none smtp.client-ip=91.218.175.182 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="AVtUPokb" Message-ID: <6e6d8390-1f9e-40cf-949d-168160fa9a15@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763554567; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=T8UxEgfEvYYIYjqonyzaX1YNHYFvCPlixYyfl5K/5Us=; b=AVtUPokbskA2fxW7sCPAzJUrWf8TDNbPt/WdsQfOCSbGOGvqVUig5Chd70lHJMkyln4ufj X6Bg1RKVDftg0vFjwYVYCXvoFKw63N958H75bSqPHgoSBbSpEmPqQpJlqP6Lz5U8HFdbCb XKACOfahN120NBnxDteAgU+KBrLLN4I= Date: Wed, 19 Nov 2025 20:15:58 +0800 Precedence: bulk X-Mailing-List: linux-parisc@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH v2 7/7] mm: enable PT_RECLAIM on all 64-bit architectures To: "David Hildenbrand (Red Hat)" , 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: <9b55623a-4606-4610-a0fe-55b8cd6b95e7@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <9b55623a-4606-4610-a0fe-55b8cd6b95e7@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/19/25 7:38 PM, David Hildenbrand (Red Hat) wrote: > On 19.11.25 08:31, Qi Zheng wrote: >> From: Qi Zheng >> >> Now, the MMU_GATHER_RCU_TABLE_FREE is enabled on all 64-bit >> architectures, >> so make PT_RECLAIM depend on 64BIT, thereby enabling PT_RECLAIM on all >> 64-bit architectures. >> >> 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 eac2e86056902..96bff81fd4787 100644 >> --- a/arch/x86/Kconfig >> +++ b/arch/x86/Kconfig >> @@ -330,7 +330,6 @@ 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 d548976d0e0ad..94eec5c0cad96 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -1448,14 +1448,9 @@ 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 64BIT > > As discussed in the other thread, likely > > config PT_RECLAIM >     def_bool y >     depends on MMU_GATHER_RCU_TABLE_FREE && 64BIT > > Could be nice, and if possible even dropping the 64BIT limitation as > well if there is no need to. I think it's ok to drop the 64BIT limitation. There should be some 32-bit architectures that already enable MMU_GATHER_RCU_TABLE_FREE. > >