From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-188.mta1.migadu.com (out-188.mta1.migadu.com [95.215.58.188]) (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 79DE7354AE6; Tue, 18 Nov 2025 12:03:49 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.188 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763467431; cv=none; b=nssJt/u+jYZ4zVxJD337yziCAjV1diblUXb9S/DwwgznlIapHtmuMcIFRD7AZa9rE+6+BmAAFbxvnNavdxTQ+8fkvIGN7f3ROtvBcZ/++FCLve1SYZTpnq6Iw46JSf/gpBrIiGScUo0DqJJ/ejdbG2t8YDWzZmObrduHTb1EphQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1763467431; c=relaxed/simple; bh=r19qXNtm3urYqAimszpeFMMBfwkKku5yTeyTyto+D7w=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=kQveE0JgU4AdHEhBGijzVOqQozBXPwtrnvOUqZi+QpMASahx8nzEiQCk834eIA5M71TF7cxS9gsuLg/YSLG0tIWvSEro6JmtKwLPJZqKokzRGHp9R7GViavY/1wV23t+EGW2IuTijJ3t1jbTurpjWb7WPK665v+GRosdIO/3YUg= 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=Z9Rbcq7i; arc=none smtp.client-ip=95.215.58.188 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="Z9Rbcq7i" Message-ID: <195baf7c-1f4e-46a4-a4aa-e68e7d00c0f9@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763467417; 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=YSfDkQJHByC5W64S3r1RZBfV7l+QzHRtZt5IkHkWjXM=; b=Z9Rbcq7i2Y1LGHCoUGuTi6ppSLunSulmRKUQ4pjayjy42viyJ+DcXrTYmImrfSRJw+UKR4 UVTRGLFHLTlNdVaXnjT3ixLkagqhNZyq0Aqov/I7FCpMijq/fe4cVtkKv+q+YaHP5txxbN qqqQe//KpgfJbRYA+2BGf/imvJ4aYQ4= Date: Tue, 18 Nov 2025 20:02:30 +0800 Precedence: bulk X-Mailing-List: linux-alpha@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Subject: Re: [PATCH 7/7] mm: make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE_FREE && 64BIT 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 Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, Qi Zheng References: <0a4d1e6f0bf299cafd1fc624f965bd1ca542cea8.1763117269.git.zhengqi.arch@bytedance.com> <355d3bf3-c6bc-403e-9f19-89259d868611@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <355d3bf3-c6bc-403e-9f19-89259d868611@kernel.org> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT On 11/18/25 12:57 AM, David Hildenbrand (Red Hat) wrote: > On 14.11.25 12:11, Qi Zheng wrote: >> From: Qi Zheng > > Subject: s/&&/&/ will do. > >> >> Make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE_FREE so that PT_RECLAIM >> can >> be enabled by default on all architectures that support >> MMU_GATHER_RCU_TABLE_FREE. >> >> Considering that a large number of PTE page table pages (such as 100GB+) >> can only be caused on a 64-bit system, let PT_RECLAIM also depend on >> 64BIT. >> >> Signed-off-by: Qi Zheng >> --- >>   arch/x86/Kconfig | 1 - >>   mm/Kconfig       | 6 +----- >>   2 files changed, 1 insertion(+), 6 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 a5a90b169435d..e795fbd69e50c 100644 >> --- a/mm/Kconfig >> +++ b/mm/Kconfig >> @@ -1440,14 +1440,10 @@ 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 >> +    depends on MMU_GATHER_RCU_TABLE_FREE && MMU && SMP && 64BIT > > Who would we have MMU_GATHER_RCU_TABLE_FREE without MMU? (can we drop > the MMU part) OK. > > Why do we care about SMP in the first place? (can we frop SMP) OK. > > But I also wonder why we need "MMU_GATHER_RCU_TABLE_FREE && 64BIT": > > Would it be harmful on 32bit (sure, we might not reclaim as much, but > still there is memory to be reclaimed?)? This is also fine on 32bit, but the benefits are not significant, So I chose to enable it only on 64-bit. I actually tried enabling MMU_GATHER_RCU_TABLE_FREE on all architectures, and apart from sparc32 being a bit troublesome (because it uses mm->page_table_lock for synchronization within __pte_free_tlb()), the modifications were relatively simple. > > If all 64BIT support MMU_GATHER_RCU_TABLE_FREE (as you previously > state), why can't we only check for 64BIT? OK, will do. Thanks, Qi > 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 6B35ECED631 for ; Tue, 18 Nov 2025 12:03:55 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender:Content-Type: Content-Transfer-Encoding:List-Subscribe:List-Help:List-Post:List-Archive: List-Unsubscribe:List-Id: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=i9gYNQS9Hmi/HcM83famtqkIqvhfaVB2WBhQlUDs3Wo=; b=g6AiJckrKTn4R2 VO3iapUsmKaCp6zhvOrWaokVdwc+sbd5NPGAYFYBuELoZR4WZ95xieIrTS/xVJ8skmAL/x12qjwSI sOFvlJZpKoyO3gpdtRLtBKEOFx0XhPQMV0nF6ivQDB8EAekFi61y9fdYslZTPq1XHGFLwDe3pBdP0 HbVDvr+TcMdwp0+tDhdrGabL7hom0HsNl5xgGH53OPKOkK3OjyL0BdPmCKTyNyY18znSCjzOhYsxN ElIP7idNiK3t+L/Wkzu7xGNi43f3RuTr98yRhUt3PeHT+WMid5DmWJpgiRFC6s/W3Cizc5iUGCw2t oy6PoMFcImEup5CRe7HQ==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.98.2 #2 (Red Hat Linux)) id 1vLKR9-00000000NRw-0hP8; Tue, 18 Nov 2025 12:03:55 +0000 Received: from out-174.mta1.migadu.com ([2001:41d0:203:375::ae]) by bombadil.infradead.org with esmtps (Exim 4.98.2 #2 (Red Hat Linux)) id 1vLKR6-00000000NQl-0bwT for linux-snps-arc@lists.infradead.org; Tue, 18 Nov 2025 12:03:53 +0000 Message-ID: <195baf7c-1f4e-46a4-a4aa-e68e7d00c0f9@linux.dev> DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1763467417; 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=YSfDkQJHByC5W64S3r1RZBfV7l+QzHRtZt5IkHkWjXM=; b=Z9Rbcq7i2Y1LGHCoUGuTi6ppSLunSulmRKUQ4pjayjy42viyJ+DcXrTYmImrfSRJw+UKR4 UVTRGLFHLTlNdVaXnjT3ixLkagqhNZyq0Aqov/I7FCpMijq/fe4cVtkKv+q+YaHP5txxbN qqqQe//KpgfJbRYA+2BGf/imvJ4aYQ4= Date: Tue, 18 Nov 2025 20:02:30 +0800 MIME-Version: 1.0 Subject: Re: [PATCH 7/7] mm: make PT_RECLAIM depend on MMU_GATHER_RCU_TABLE_FREE && 64BIT 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 Cc: linux-arch@vger.kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, linux-alpha@vger.kernel.org, linux-snps-arc@lists.infradead.org, loongarch@lists.linux.dev, linux-mips@vger.kernel.org, linux-parisc@vger.kernel.org, linux-um@lists.infradead.org, Qi Zheng References: <0a4d1e6f0bf299cafd1fc624f965bd1ca542cea8.1763117269.git.zhengqi.arch@bytedance.com> <355d3bf3-c6bc-403e-9f19-89259d868611@kernel.org> X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. From: Qi Zheng In-Reply-To: <355d3bf3-c6bc-403e-9f19-89259d868611@kernel.org> X-Migadu-Flow: FLOW_OUT X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20251118_040352_415362_ABCB53C2 X-CRM114-Status: GOOD ( 17.75 ) X-BeenThere: linux-snps-arc@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: Linux on Synopsys ARC Processors List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Transfer-Encoding: base64 Content-Type: text/plain; charset="utf-8"; Format="flowed" Sender: "linux-snps-arc" Errors-To: linux-snps-arc-bounces+linux-snps-arc=archiver.kernel.org@lists.infradead.org CgpPbiAxMS8xOC8yNSAxMjo1NyBBTSwgRGF2aWQgSGlsZGVuYnJhbmQgKFJlZCBIYXQpIHdyb3Rl Ogo+IE9uIDE0LjExLjI1IDEyOjExLCBRaSBaaGVuZyB3cm90ZToKPj4gRnJvbTogUWkgWmhlbmcg PHpoZW5ncWkuYXJjaEBieXRlZGFuY2UuY29tPgo+IAo+IFN1YmplY3Q6IHMvJiYvJi8KCndpbGwg ZG8uCgo+IAo+Pgo+PiBNYWtlIFBUX1JFQ0xBSU0gZGVwZW5kIG9uIE1NVV9HQVRIRVJfUkNVX1RB QkxFX0ZSRUUgc28gdGhhdCBQVF9SRUNMQUlNIAo+PiBjYW4KPj4gYmUgZW5hYmxlZCBieSBkZWZh dWx0IG9uIGFsbCBhcmNoaXRlY3R1cmVzIHRoYXQgc3VwcG9ydAo+PiBNTVVfR0FUSEVSX1JDVV9U QUJMRV9GUkVFLgo+Pgo+PiBDb25zaWRlcmluZyB0aGF0IGEgbGFyZ2UgbnVtYmVyIG9mIFBURSBw YWdlIHRhYmxlIHBhZ2VzIChzdWNoIGFzIDEwMEdCKykKPj4gY2FuIG9ubHkgYmUgY2F1c2VkIG9u IGEgNjQtYml0IHN5c3RlbSwgbGV0IFBUX1JFQ0xBSU0gYWxzbyBkZXBlbmQgb24KPj4gNjRCSVQu Cj4+Cj4+IFNpZ25lZC1vZmYtYnk6IFFpIFpoZW5nIDx6aGVuZ3FpLmFyY2hAYnl0ZWRhbmNlLmNv bT4KPj4gLS0tCj4+IMKgIGFyY2gveDg2L0tjb25maWcgfCAxIC0KPj4gwqAgbW0vS2NvbmZpZ8Kg wqDCoMKgwqDCoCB8IDYgKy0tLS0tCj4+IMKgIDIgZmlsZXMgY2hhbmdlZCwgMSBpbnNlcnRpb24o KyksIDYgZGVsZXRpb25zKC0pCj4+Cj4+IGRpZmYgLS1naXQgYS9hcmNoL3g4Ni9LY29uZmlnIGIv YXJjaC94ODYvS2NvbmZpZwo+PiBpbmRleCBlYWMyZTg2MDU2OTAyLi45NmJmZjgxZmQ0Nzg3IDEw MDY0NAo+PiAtLS0gYS9hcmNoL3g4Ni9LY29uZmlnCj4+ICsrKyBiL2FyY2gveDg2L0tjb25maWcK Pj4gQEAgLTMzMCw3ICszMzAsNiBAQCBjb25maWcgWDg2Cj4+IMKgwqDCoMKgwqAgc2VsZWN0IEZV TkNUSU9OX0FMSUdOTUVOVF80Qgo+PiDCoMKgwqDCoMKgIGltcGx5IElNQV9TRUNVUkVfQU5EX09S X1RSVVNURURfQk9PVMKgwqDCoCBpZiBFRkkKPj4gwqDCoMKgwqDCoCBzZWxlY3QgSEFWRV9EWU5B TUlDX0ZUUkFDRV9OT19QQVRDSEFCTEUKPj4gLcKgwqDCoCBzZWxlY3QgQVJDSF9TVVBQT1JUU19Q VF9SRUNMQUlNwqDCoMKgwqDCoMKgwqAgaWYgWDg2XzY0Cj4+IMKgwqDCoMKgwqAgc2VsZWN0IEFS Q0hfU1VQUE9SVFNfU0NIRURfU01UwqDCoMKgwqDCoMKgwqAgaWYgU01QCj4+IMKgwqDCoMKgwqAg c2VsZWN0IFNDSEVEX1NNVMKgwqDCoMKgwqDCoMKgwqDCoMKgwqAgaWYgU01QCj4+IMKgwqDCoMKg wqAgc2VsZWN0IEFSQ0hfU1VQUE9SVFNfU0NIRURfQ0xVU1RFUsKgwqDCoCBpZiBTTVAKPj4gZGlm ZiAtLWdpdCBhL21tL0tjb25maWcgYi9tbS9LY29uZmlnCj4+IGluZGV4IGE1YTkwYjE2OTQzNWQu LmU3OTVmYmQ2OWU1MGMgMTAwNjQ0Cj4+IC0tLSBhL21tL0tjb25maWcKPj4gKysrIGIvbW0vS2Nv bmZpZwo+PiBAQCAtMTQ0MCwxNCArMTQ0MCwxMCBAQCBjb25maWcgQVJDSF9IQVNfVVNFUl9TSEFE T1dfU1RBQ0sKPj4gwqDCoMKgwqDCoMKgwqAgVGhlIGFyY2hpdGVjdHVyZSBoYXMgaGFyZHdhcmUg c3VwcG9ydCBmb3IgdXNlcnNwYWNlIHNoYWRvdyBjYWxsCj4+IMKgwqDCoMKgwqDCoMKgwqDCoMKg wqAgc3RhY2tzIChlZywgeDg2IENFVCwgYXJtNjQgR0NTIG9yIFJJU0MtViBaaWNmaXNzKS4KPj4g LWNvbmZpZyBBUkNIX1NVUFBPUlRTX1BUX1JFQ0xBSU0KPj4gLcKgwqDCoCBkZWZfYm9vbCBuCj4+ IC0KPj4gwqAgY29uZmlnIFBUX1JFQ0xBSU0KPj4gwqDCoMKgwqDCoCBib29sICJyZWNsYWltIGVt cHR5IHVzZXIgcGFnZSB0YWJsZSBwYWdlcyIKPj4gwqDCoMKgwqDCoCBkZWZhdWx0IHkKPj4gLcKg wqDCoCBkZXBlbmRzIG9uIEFSQ0hfU1VQUE9SVFNfUFRfUkVDTEFJTSAmJiBNTVUgJiYgU01QCj4+ IC3CoMKgwqAgc2VsZWN0IE1NVV9HQVRIRVJfUkNVX1RBQkxFX0ZSRUUKPj4gK8KgwqDCoCBkZXBl bmRzIG9uIE1NVV9HQVRIRVJfUkNVX1RBQkxFX0ZSRUUgJiYgTU1VICYmIFNNUCAmJiA2NEJJVAo+ IAo+IFdobyB3b3VsZCB3ZSBoYXZlIE1NVV9HQVRIRVJfUkNVX1RBQkxFX0ZSRUUgd2l0aG91dCBN TVU/IChjYW4gd2UgZHJvcCAKPiB0aGUgTU1VIHBhcnQpCgpPSy4KCj4gCj4gV2h5IGRvIHdlIGNh cmUgYWJvdXQgU01QIGluIHRoZSBmaXJzdCBwbGFjZT8gKGNhbiB3ZSBmcm9wIFNNUCkKCk9LLgoK PiAKPiBCdXQgSSBhbHNvIHdvbmRlciB3aHkgd2UgbmVlZCAiTU1VX0dBVEhFUl9SQ1VfVEFCTEVf RlJFRSAmJiA2NEJJVCI6Cj4gCj4gV291bGQgaXQgYmUgaGFybWZ1bCBvbiAzMmJpdCAoc3VyZSwg d2UgbWlnaHQgbm90IHJlY2xhaW0gYXMgbXVjaCwgYnV0IAo+IHN0aWxsIHRoZXJlIGlzIG1lbW9y eSB0byBiZSByZWNsYWltZWQ/KT8KClRoaXMgaXMgYWxzbyBmaW5lIG9uIDMyYml0LCBidXQgdGhl IGJlbmVmaXRzIGFyZSBub3Qgc2lnbmlmaWNhbnQsIFNvIEkKY2hvc2UgdG8gZW5hYmxlIGl0IG9u bHkgb24gNjQtYml0LgoKSSBhY3R1YWxseSB0cmllZCBlbmFibGluZyBNTVVfR0FUSEVSX1JDVV9U QUJMRV9GUkVFIG9uIGFsbAphcmNoaXRlY3R1cmVzLCBhbmQgYXBhcnQgZnJvbSBzcGFyYzMyIGJl aW5nIGEgYml0IHRyb3VibGVzb21lIChiZWNhdXNlCml0IHVzZXMgbW0tPnBhZ2VfdGFibGVfbG9j ayBmb3Igc3luY2hyb25pemF0aW9uIHdpdGhpbgpfX3B0ZV9mcmVlX3RsYigpKSwgdGhlIG1vZGlm aWNhdGlvbnMgd2VyZSByZWxhdGl2ZWx5IHNpbXBsZS4KCj4gCj4gSWYgYWxsIDY0QklUIHN1cHBv cnQgTU1VX0dBVEhFUl9SQ1VfVEFCTEVfRlJFRSAoYXMgeW91IHByZXZpb3VzbHkgCj4gc3RhdGUp LCB3aHkgY2FuJ3Qgd2Ugb25seSBjaGVjayBmb3IgNjRCSVQ/CgpPSywgd2lsbCBkby4KClRoYW5r cywKUWkKCj4gCgoKX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19fX19f X18KbGludXgtc25wcy1hcmMgbWFpbGluZyBsaXN0CmxpbnV4LXNucHMtYXJjQGxpc3RzLmluZnJh ZGVhZC5vcmcKaHR0cDovL2xpc3RzLmluZnJhZGVhZC5vcmcvbWFpbG1hbi9saXN0aW5mby9saW51 eC1zbnBzLWFyYwo=