From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 9B808CF31B5 for ; Wed, 19 Nov 2025 12:16:15 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:List-Subscribe:List-Help :List-Post:List-Archive:List-Unsubscribe:List-Id:Content-Transfer-Encoding: Content-Type:In-Reply-To:From:References:Cc:To:Subject:MIME-Version:Date: Message-ID:Reply-To:Content-ID:Content-Description:Resent-Date:Resent-From: Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Owner; bh=T8UxEgfEvYYIYjqonyzaX1YNHYFvCPlixYyfl5K/5Us=; b=DRAMUFZ0zoX03D9OBFqVeUnPzD VCyFsFcibcAeWnlbXOD587WedmVjtgp6rRfGZDPC0wpkQShjYoiJpD6jmcKpcdRPYcrL3I72Htdvo mxrhqBQxvsC5knn08qlYrHy0DSvwCeVEoZyz3pZC8LI0RyrRbez6JlkK0nkqsOy10a8gHnWGjAGA/ w25D/pRR8Rl6JA1lr51az+TSCVge4Znlqn+iLq1TIiLcu9q0fQrKe/hwAK+xrVXo65UzXsQcU4bMa VlGmC3OrgewUX+6ZvaF22mFrSYen7NVW6Q03lsUmO5XLXCi+mbASHvyYXoBs9wVy3nUyYTYMHCQtX 3tMt5Nug==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vLh6d-000000036Nd-1ev6; Wed, 19 Nov 2025 12:16:15 +0000 Received: from out-173.mta0.migadu.com ([2001:41d0:1004:224b::ad]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vLh6a-000000036NA-3UIM for linux-um@lists.infradead.org; Wed, 19 Nov 2025 12:16:14 +0000 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 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 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251119_041613_017437_EF2BED3C X-CRM114-Status: GOOD ( 14.05 ) X-BeenThere: linux-um@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-um" Errors-To: linux-um-bounces+linux-um=archiver.kernel.org@lists.infradead.org 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. > >