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 kanga.kvack.org (kanga.kvack.org [205.233.56.17]) (using TLSv1 with cipher DHE-RSA-AES256-SHA (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id CD3BDF0182E for ; Fri, 6 Mar 2026 12:49:22 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 42E756B00A7; Fri, 6 Mar 2026 07:49:22 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 3EF1E6B00A8; Fri, 6 Mar 2026 07:49:22 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 2D4A06B00A9; Fri, 6 Mar 2026 07:49:22 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0014.hostedemail.com [216.40.44.14]) by kanga.kvack.org (Postfix) with ESMTP id 17F1B6B00A7 for ; Fri, 6 Mar 2026 07:49:22 -0500 (EST) Received: from smtpin04.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id CFF3D1B80BF for ; Fri, 6 Mar 2026 12:49:21 +0000 (UTC) X-FDA: 84515618922.04.1AAEB37 Received: from fra-out-009.esa.eu-central-1.outbound.mail-perimeter.amazon.com (fra-out-009.esa.eu-central-1.outbound.mail-perimeter.amazon.com [3.64.237.68]) by imf25.hostedemail.com (Postfix) with ESMTP id 6F9A7A000E for ; Fri, 6 Mar 2026 12:49:19 +0000 (UTC) Authentication-Results: imf25.hostedemail.com; dkim=pass header.d=amazon.com header.s=amazoncorp2 header.b=Ay0F96w3; spf=pass (imf25.hostedemail.com: domain of "prvs=518a0fcdf=kalyazin@amazon.co.uk" designates 3.64.237.68 as permitted sender) smtp.mailfrom="prvs=518a0fcdf=kalyazin@amazon.co.uk"; dmarc=pass (policy=quarantine) header.from=amazon.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1772801359; h=from:from:sender:reply-to: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:dkim-signature; bh=bRMHQdQ5GfQ08jWBNyGRBN4vXmA9+fBBCWCkl04FNjQ=; b=PuBisf74ypRmeeiZ5NUj72gGuBSqY4SnUYOO8IuN6imy1s0hP0OpZ3ufv0yTYfXL3D0v8t iAaDXPokkAcJEGU6mze594aqoYUb5ZjD/t7uf21D9JoLc3uv8LCTPz/35gcRozALTAZovO Bx3+KmrnsN75pocYRocXvXgmkDarZh8= ARC-Authentication-Results: i=1; imf25.hostedemail.com; dkim=pass header.d=amazon.com header.s=amazoncorp2 header.b=Ay0F96w3; spf=pass (imf25.hostedemail.com: domain of "prvs=518a0fcdf=kalyazin@amazon.co.uk" designates 3.64.237.68 as permitted sender) smtp.mailfrom="prvs=518a0fcdf=kalyazin@amazon.co.uk"; dmarc=pass (policy=quarantine) header.from=amazon.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1772801359; a=rsa-sha256; cv=none; b=uioDiYYbHKeSgJbnjkv/8F0Xa7PZvZKXOrV0ifDtpWsiRzlT2vUjds2TRgSwfTxfozm0pF Vn8480oEPOtFmjuPVS6JVwcIoq2GhuZsJGQkF/+MFzlK/gpTHUXJygbzk8K+UP0fvkyQyS KNViHRxXnRsTkc82E7Uc2VUZq23PxVw= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=amazon.com; i=@amazon.com; q=dns/txt; s=amazoncorp2; t=1772801359; x=1804337359; h=message-id:date:mime-version:reply-to:subject:to:cc: references:from:in-reply-to:content-transfer-encoding; bh=bRMHQdQ5GfQ08jWBNyGRBN4vXmA9+fBBCWCkl04FNjQ=; b=Ay0F96w3RVw2nm9FgxFQd0sC5fktbIchaKwSfO23sZWwD7ihM2x2wRvT NoKdM31efeHTiGLW9DMguDe/Kb68smNDT1K10yhnwJoTiAzCa05BT+6FD A+J+mTdjwVFGVQLz76hoa0J9Je0mjftPrNbSOq0meXlU1s/s9l7QEifsX jyR0G8XVNrAzoGcyeravQ7n4UrxLrS0pRljOw3yw8Ozi/ciEBUCUuL8JZ WkBlymruZ6q/BE0WZSyw/mAXwhXhxNUrzbnC2FSyqE6i3LrsGi/2fz612 r35wqmeOklrk6CS6TJTw7FCKrYi/13CM80qoesc9ZQY/LQt7ivvLAvMPj g==; X-CSE-ConnectionGUID: +CBc8LTUTFyKU3vgne5J+A== X-CSE-MsgGUID: SsgvaCDKTQyRTYkBnx7yEA== X-IronPort-AV: E=Sophos;i="6.23,104,1770595200"; d="scan'208";a="10334046" Received: from ip-10-6-6-97.eu-central-1.compute.internal (HELO smtpout.naws.eu-central-1.prod.farcaster.email.amazon.dev) ([10.6.6.97]) by internal-fra-out-009.esa.eu-central-1.outbound.mail-perimeter.amazon.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 06 Mar 2026 12:49:17 +0000 Received: from EX19MTAEUC001.ant.amazon.com [54.240.197.225:27792] by smtpin.naws.eu-central-1.prod.farcaster.email.amazon.dev [10.0.8.50:2525] with esmtp (Farcaster) id 3c65634d-d2ee-42b8-a0db-5e2cd1d9a376; Fri, 6 Mar 2026 12:49:17 +0000 (UTC) X-Farcaster-Flow-ID: 3c65634d-d2ee-42b8-a0db-5e2cd1d9a376 Received: from EX19D005EUB003.ant.amazon.com (10.252.51.31) by EX19MTAEUC001.ant.amazon.com (10.252.51.193) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.37; Fri, 6 Mar 2026 12:49:14 +0000 Received: from [192.168.2.180] (10.106.83.26) by EX19D005EUB003.ant.amazon.com (10.252.51.31) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_128_CBC_SHA) id 15.2.2562.37; Fri, 6 Mar 2026 12:49:09 +0000 Message-ID: Date: Fri, 6 Mar 2026 12:49:08 +0000 MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Reply-To: Subject: Re: [PATCH v10 04/15] mm/gup: drop local variable in gup_fast_folio_allowed To: "David Hildenbrand (Arm)" , "Kalyazin, Nikita" , "kvm@vger.kernel.org" , "linux-doc@vger.kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "kvmarm@lists.linux.dev" , "linux-fsdevel@vger.kernel.org" , "linux-mm@kvack.org" , "bpf@vger.kernel.org" , "linux-kselftest@vger.kernel.org" , "kernel@xen0n.name" , "linux-riscv@lists.infradead.org" , "linux-s390@vger.kernel.org" , "loongarch@lists.linux.dev" CC: "pbonzini@redhat.com" , "corbet@lwn.net" , "maz@kernel.org" , "oupton@kernel.org" , "joey.gouly@arm.com" , "suzuki.poulose@arm.com" , "yuzenghui@huawei.com" , "catalin.marinas@arm.com" , "will@kernel.org" , "seanjc@google.com" , "tglx@kernel.org" , "mingo@redhat.com" , "bp@alien8.de" , "dave.hansen@linux.intel.com" , "x86@kernel.org" , "hpa@zytor.com" , "luto@kernel.org" , "peterz@infradead.org" , "willy@infradead.org" , "akpm@linux-foundation.org" , "lorenzo.stoakes@oracle.com" , "vbabka@suse.cz" , "rppt@kernel.org" , "surenb@google.com" , "mhocko@suse.com" , "ast@kernel.org" , "daniel@iogearbox.net" , "andrii@kernel.org" , "martin.lau@linux.dev" , "eddyz87@gmail.com" , "song@kernel.org" , "yonghong.song@linux.dev" , "john.fastabend@gmail.com" , "kpsingh@kernel.org" , "sdf@fomichev.me" , "haoluo@google.com" , "jolsa@kernel.org" , "jgg@ziepe.ca" , "jhubbard@nvidia.com" , "peterx@redhat.com" , "jannh@google.com" , "pfalcato@suse.de" , "shuah@kernel.org" , "riel@surriel.com" , "ryan.roberts@arm.com" , "jgross@suse.com" , "yu-cheng.yu@intel.com" , "kas@kernel.org" , "coxu@redhat.com" , "kevin.brodsky@arm.com" , "ackerleytng@google.com" , "maobibo@loongson.cn" , "prsampat@amd.com" , "mlevitsk@redhat.com" , "jmattson@google.com" , "jthoughton@google.com" , "agordeev@linux.ibm.com" , "alex@ghiti.fr" , "aou@eecs.berkeley.edu" , "borntraeger@linux.ibm.com" , "chenhuacai@kernel.org" , "dev.jain@arm.com" , "gor@linux.ibm.com" , "hca@linux.ibm.com" , "palmer@dabbelt.com" , "pjw@kernel.org" , "shijie@os.amperecomputing.com" , "svens@linux.ibm.com" , "thuth@redhat.com" , "wyihan@google.com" , "yang@os.amperecomputing.com" , "Jonathan.Cameron@huawei.com" , "Liam.Howlett@oracle.com" , "urezki@gmail.com" , "zhengqi.arch@bytedance.com" , "gerald.schaefer@linux.ibm.com" , "jiayuan.chen@shopee.com" , "lenb@kernel.org" , "osalvador@suse.de" , "pavel@kernel.org" , "rafael@kernel.org" , "vannapurve@google.com" , "jackmanb@google.com" , "aneesh.kumar@kernel.org" , "patrick.roy@linux.dev" , "Thomson, Jack" , "Itazuri, Takahiro" , "Manwaring, Derek" , "Cali, Marco" References: <20260126164445.11867-1-kalyazin@amazon.com> <20260126164445.11867-5-kalyazin@amazon.com> Content-Language: en-US From: Nikita Kalyazin In-Reply-To: Content-Type: text/plain; charset="UTF-8"; format=flowed Content-Transfer-Encoding: 7bit X-Originating-IP: [10.106.83.26] X-ClientProxiedBy: EX19D015EUB002.ant.amazon.com (10.252.51.123) To EX19D005EUB003.ant.amazon.com (10.252.51.31) X-Rspamd-Queue-Id: 6F9A7A000E X-Stat-Signature: zhpqgti1sydywtyaonbidrkbhga14heb X-Rspam-User: X-Rspamd-Server: rspam05 X-HE-Tag: 1772801359-842345 X-HE-Meta: U2FsdGVkX19IgdC21YU79p9/xcsl9jW0MIdzL3pXdZBmvkMxocpS32FzeAEfPidkRG8DDe0RrsfhJyBr1AlNRga26fb6VfDTaWxrjeVptw07ku6jOTxYI9JbOfCCKeUo0FaMuGLSlS+zHinXEjfo6anZhJH24+L7lfGAYDRVYay8yfpmCjIF+A7vfkDRdmlRW16CPClYNJhlExaTmY41vrvXFfDpkdF7VoWP513LsIdEa2X02HuARidj9OU+cg/9JwMY4U9ZZU4o3DZnrhaMdTzHhppwpWUyAj1oR31VBZIJtq3jrIp7LHvbR/xPTPcgiN/RSEHlH1Fo3hNFPuw2YHInyf04uKrfRYznxRHH53mKomMISHVfKojUP3q5A9RPPhFRJ/8fBy1RPoiXM6izdmek3xPeljmesyCgENlZoDVVryG6510bH9eXewG8JdAd0g0baLiwIYT/5nkjUQgzvMjn/8qW1SdK/AL2PA7Kp8F2gL3JkKxNsYUN49xVBTJLpF6HQFGG46/eXRdI6kK9FYscFibC6Xhr/UxQKI7iPVljt5y9jnK1DPjO/GRD7WradBtlmBsLDMS8eVPi4OdtfdNs9uB8dZD5O+ghFBgg6kVUA+D4Ohnrb8HyYIVB0+AwYEXoImZKhtC7ABERJw5riP+wOEyWIQ4ascwiD7kDmDQyQvg4kuhfctu8yfpumxraPH6xZU/eda6sukCGgxSnjhtyF4d853+tizMQIcJi0c7S5UoFApF2dD2/Vxk1Fpf5D9z43XGJ/CNdI0IQR83Jv3g+b7/y4reZ9w0AMPXeGp2YN4BpJnITT0X1qnrSier56Fnuipzbt4D72aoknGRPD8KiwcUiaF648GuKZbgLfsY6g3SXUeQjJC/U4VqL2HjKHkfmE+L3q1z7mZwTwjsjOJUeYJ42y4qIpJBtJJ0urAg0G1dfGGgBHudDyATXnWQhn3/dTdqTcE1NOmAeJ1+ ca0c6uuv 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 Bv6gEPRS 13oiOF4OUw5/XBMR0TNlphwe+W4rUrxB+937qIt3P6q6D+C2tAIkNDFIBCJ3UQTF Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: On 05/03/2026 19:07, David Hildenbrand (Arm) wrote: > On 1/26/26 17:47, Kalyazin, Nikita wrote: >> From: Nikita Kalyazin >> >> Move the check for pinning closer to where the result is used. >> No functional changes. >> >> Signed-off-by: Nikita Kalyazin >> --- >> mm/gup.c | 19 ++++++++----------- >> 1 file changed, 8 insertions(+), 11 deletions(-) >> >> diff --git a/mm/gup.c b/mm/gup.c >> index 9cad53acbc99..e72dacce3e34 100644 >> --- a/mm/gup.c >> +++ b/mm/gup.c >> @@ -2737,18 +2737,9 @@ EXPORT_SYMBOL(get_user_pages_unlocked); >> */ >> static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) >> { >> - bool reject_file_backed = false; >> struct address_space *mapping; >> unsigned long mapping_flags; >> >> - /* >> - * If we aren't pinning then no problematic write can occur. A long term >> - * pin is the most egregious case so this is the one we disallow. >> - */ >> - if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) == >> - (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) >> - reject_file_backed = true; >> - >> /* We hold a folio reference, so we can safely access folio fields. */ >> if (WARN_ON_ONCE(folio_test_slab(folio))) >> return false; >> @@ -2793,8 +2784,14 @@ static bool gup_fast_folio_allowed(struct folio *folio, unsigned int flags) >> */ >> if (secretmem_mapping(mapping)) >> return false; >> - /* The only remaining allowed file system is shmem. */ >> - return !reject_file_backed || shmem_mapping(mapping); >> + >> + /* >> + * If we aren't pinning then no problematic write can occur. A long term >> + * pin is the most egregious case so this is the one we disallow. >> + * Also check the only remaining allowed file system - shmem. >> + */ >> + return (flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != >> + (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE) || shmem_mapping(mapping); > > Best to keep this split and a bit more readable. > > /* > * If we aren't pinning then no problematic write can occur. A writable > * long term pin is the most egregious case, so this is the one we > * allow only for ... > */ > if ((flags & (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE)) != > (FOLL_PIN | FOLL_LONGTERM | FOLL_WRITE) > return true; > /* ... hugetlb (which we allowed above already) and shared memory. */ > return shmem_mapping(mapping); Makes sense, thank you! > >> } >> >> static void __maybe_unused gup_fast_undo_dev_pagemap(int *nr, int nr_start, > > > -- > Cheers, > > David