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]) by smtp.lore.kernel.org (Postfix) with ESMTP id AE0EEC4708D for ; Wed, 7 Dec 2022 21:18:34 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 1A6F08E0003; Wed, 7 Dec 2022 16:18:34 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 1578F8E0001; Wed, 7 Dec 2022 16:18:34 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id F145E8E0003; Wed, 7 Dec 2022 16:18:33 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0013.hostedemail.com [216.40.44.13]) by kanga.kvack.org (Postfix) with ESMTP id DEAC88E0001 for ; Wed, 7 Dec 2022 16:18:33 -0500 (EST) Received: from smtpin10.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id A5AA31C5FDD for ; Wed, 7 Dec 2022 21:18:33 +0000 (UTC) X-FDA: 80216774106.10.4E7274A Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by imf05.hostedemail.com (Postfix) with ESMTP id 1B7A710001A for ; Wed, 7 Dec 2022 21:18:29 +0000 (UTC) Authentication-Results: imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="N3Ir3Nb/"; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1670447910; a=rsa-sha256; cv=none; b=JhIkWkNbGM15c0O+8C41ut1faA/xKfgDaV6nGKNLpt/REoSCmZY1EN+5UJw7L1dEzNOg6n EzrIEw953WPOrMYvh2zKT3ss5nyjRSkFSVT1Kwsq0LpfjCYETSfMpUgSES0hI1FBr41ti/ D3hHtHHO3LkVOv8S000Cbo/UvyPFmR0= ARC-Authentication-Results: i=1; imf05.hostedemail.com; dkim=pass header.d=redhat.com header.s=mimecast20190719 header.b="N3Ir3Nb/"; spf=pass (imf05.hostedemail.com: domain of david@redhat.com designates 170.10.133.124 as permitted sender) smtp.mailfrom=david@redhat.com; dmarc=pass (policy=none) header.from=redhat.com ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1670447910; h=from:from:sender: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=UZoulz6jSV4QDo6LCWvnK9BE6ZYvLdrmqHb/WNLMVyI=; b=Z2KdVbRPipXkKee8ymFe5BHja5OaHOwjM6MM1lM6G7d0cwEoV+n2Lw7qjLg8QfvRmqTf+S GpptrqIXq79sN2B/xAxPMK9FrppKsA5Piyr5IJXF9/b+jbHk6pkpjuZxOrwpgd1mQTwd2j trWkvVJC1YKwGi+pSZWddzs3I0AmhWE= DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1670447910; 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=UZoulz6jSV4QDo6LCWvnK9BE6ZYvLdrmqHb/WNLMVyI=; b=N3Ir3Nb/bZc9d5ytcgEiTw/C59DO7vGupHDzAN5GKmDCzTp7VQKs6mibs/F4LEPCIghTMY ILBTHik3mWISwOr4bgIVbAPuD+HccIW0cBoGeeav068ycQhEVzySIF+8IHvz9qr3P11G4C Egr9FIXwY4UBMmzNIuPrHcmXKbgWWmI= Received: from mail-wr1-f71.google.com (mail-wr1-f71.google.com [209.85.221.71]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_128_GCM_SHA256) id us-mta-478-L3uO2R7xNPi33lv4HzK6qQ-1; Wed, 07 Dec 2022 16:18:28 -0500 X-MC-Unique: L3uO2R7xNPi33lv4HzK6qQ-1 Received: by mail-wr1-f71.google.com with SMTP id k1-20020adfb341000000b0024215e0f486so4664819wrd.21 for ; Wed, 07 Dec 2022 13:18:28 -0800 (PST) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20210112; h=content-transfer-encoding:in-reply-to:subject:organization:from :references:cc:to:content-language:user-agent:mime-version:date :message-id:x-gm-message-state:from:to:cc:subject:date:message-id :reply-to; bh=UZoulz6jSV4QDo6LCWvnK9BE6ZYvLdrmqHb/WNLMVyI=; b=tVsz5mThjnfn5iR7Qv6JHCZzZaPGSFkOz/Y6nsR/jCUAhGoMGo21JM6awTjgLV/sfH oPk3V33imH9qQfw6meJgHvtonEjJzH7s+I7UU7qKAQbl+d631I/YRYPDv5VLcmzU9xbs ZUPGGU0Z1Jj0VZAKSH2LiTYQubq/t3yicaPyDYXK0K81XoWCWBqOh6LZc1VH1XvZin59 8FbSo+vdRbHYzlV8Y6+MgSTnUGfqNVElFeQPOABj3v0u26euPJZ7hueRrMeP2hLB9K1w Lnz5IFXhocINuL17uAFRBWY+YgSwZ5BYNmXRzER30wykHc9/c7VQt5akTYg/w/Vtmiou 1IQg== X-Gm-Message-State: ANoB5pmmG5r9//8BNt0bMQ3aZP/KAJqJsTqe8lIxcrDlQgjz86T/Z5Ik 8cIPbYhDkg0PTPDkYZE/lSSp/D/3nIQYzzrtTd6FAOueTwQDulGWqGfASbLofzf93C/0n3S/ynf mlCs0MletnZo= X-Received: by 2002:a5d:4f92:0:b0:242:1845:8097 with SMTP id d18-20020a5d4f92000000b0024218458097mr27220514wru.666.1670447907490; Wed, 07 Dec 2022 13:18:27 -0800 (PST) X-Google-Smtp-Source: AA0mqf5fgorQG0KcxOAv9s8Iw+8eIlItbbpS2TXSd8gWnoUAbysFboAAFOCTtaRXkWFQxKp0ME8+pg== X-Received: by 2002:a5d:4f92:0:b0:242:1845:8097 with SMTP id d18-20020a5d4f92000000b0024218458097mr27220503wru.666.1670447907124; Wed, 07 Dec 2022 13:18:27 -0800 (PST) Received: from ?IPV6:2003:cb:c702:2500:fe2d:7534:ffa4:c1e5? (p200300cbc7022500fe2d7534ffa4c1e5.dip0.t-ipconnect.de. [2003:cb:c702:2500:fe2d:7534:ffa4:c1e5]) by smtp.gmail.com with ESMTPSA id j42-20020a05600c1c2a00b003c6d21a19a0sm3473213wms.29.2022.12.07.13.18.26 (version=TLS1_3 cipher=TLS_AES_128_GCM_SHA256 bits=128/128); Wed, 07 Dec 2022 13:18:26 -0800 (PST) Message-ID: <1f157500-2676-7cef-a84e-9224ed64e540@redhat.com> Date: Wed, 7 Dec 2022 22:18:25 +0100 MIME-Version: 1.0 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:102.0) Gecko/20100101 Thunderbird/102.5.0 To: Peter Xu Cc: linux-kernel@vger.kernel.org, linux-mm@kvack.org, Andrew Morton , Yang Shi , Hugh Dickins , Andrea Arcangeli References: <20221206105737.69478-1-david@redhat.com> From: David Hildenbrand Organization: Red Hat Subject: Re: [PATCH v2] mm/swap: fix SWP_PFN_BITS with CONFIG_PHYS_ADDR_T_64BIT on 32bit In-Reply-To: X-Mimecast-Spam-Score: 0 X-Mimecast-Originator: redhat.com Content-Language: en-US Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 7bit X-Rspam-User: X-Rspamd-Server: rspam03 X-Rspamd-Queue-Id: 1B7A710001A X-Stat-Signature: 86pmpa7sfjoywjf6xfibrxfasq3kdrkf X-HE-Tag: 1670447909-295168 X-HE-Meta: U2FsdGVkX1+IHTEskKW/VYxSuf9BghnphZuUvou7b7lQXY5gS65BK9JTB+0dRpmaDp7dbDyuHl5osWil2dbZnPch9IlB9u2Ric4Q3jxgaAyxas+R2TUBaqrHbEMI8KJjKPMAWrZq3iT88JkawFwhu8YKmAY5EzNCOXSqZfwBkXJUsyJ3wAwJWJ0M01IJ9knISNBDw+xspKKppAbyJ5FXs3BIKiqbm3X2TAseK2YpxH9gHd+q1c/P4bQ7cLxFW+pYTghmcyKl0pjI6bSdJkAx6xyMOZweX+GgpFfP9Inkfmg+VioJXMREa9ago2a4GyF+bHTXH4AMCLsjsQi44ad2aeRyGfTu/u8rJ6EgfN9HKHnUK7DhYGelPyFMmpQhfP/09zBvm96zvtpM/x8QCXSTlS28b5d0ZjsWQ662yymQRKu9BRxnJVlxSEAvdK8bKKyecg3hISnAJvPb/g4GH1i691x73i1uaMqbD7b4M/4WvXg0Zkm4r0NRZKaVWE1VStGGqg8gJFKWbkGRSitNtYSg4Ujk9F7qfQa2Bh7824TCCBFed3kQN3XVQ9V+dZ/+K06vY1R0ZuuL849cW3/wKMAtVY2ED82l4BGDrHNVzXQsBYaQx+4Z6RUeGcJT5hGLHYZNCyaTnNfewwZlRSOVRBJncmdeyBOW5A7etOwATQ5zkwjQd3evzQnb7qAZIt2k9uhfMWAb7KDL4R2fu/V2ygFadxZgrYVNS4oSd6YMcDhsqg/mOArZmC84CWqzDFnKwD8KPJ3lYhz3y3Yww5YJoz3/ftnGyMo6nmdy3znBlvpOzvCDQn03k55l3ofN1thdXqZNJ08qkQtwSo+tO+hEMO7SWFLhATt0V3OwpXu6XDqWsmK0wK3UqlUALJVLFE2Kgmx5epFmn/jedp73ftIxnUWH4LnQrSe2nbo7WzFQH3FRIpEtn5S6O/Qk56yiez+9mhfV1frXac98nznbRplerPR qXLtpFJF LCSf8bK04WbC1Qps4D2H8J5w1uXmEUr5OnMTNB9zlrnK9IS3EbSd+NuAW+kcfLbqIZScTxNwiGKiCIta7zpLPUnRvYa1vaTfusaY3gsvgyoe2S2Xosc/xX3cVNzHUSUmnuA7VPszIMciCmicREnUqrzXZxhiA4qJUdvg60YPZOsJy9+FbiPnAZsHPRP3gXUdygaHQ X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On 06.12.22 23:12, Peter Xu wrote: > On Tue, Dec 06, 2022 at 11:57:37AM +0100, David Hildenbrand wrote: >> We use "unsigned long" to store a PFN in the kernel and phys_addr_t to >> store a physical address. >> >> On a 64bit system, both are 64bit wide. However, on a 32bit system, the >> latter might be 64bit wide. This is, for example, the case on x86 with >> PAE: phys_addr_t and PTEs are 64bit wide, while "unsigned long" only >> spans 32bit. >> >> The current definition of SWP_PFN_BITS without MAX_PHYSMEM_BITS misses >> that case, and assumes that the maximum PFN is limited by an 32bit >> phys_addr_t. This implies, that SWP_PFN_BITS will currently only be able to >> cover 4 GiB - 1 on any 32bit system with 4k page size, which is wrong. >> >> Let's rely on the number of bits in phys_addr_t instead, but make sure to >> not exceed the maximum swap offset, to not make the BUILD_BUG_ON() in >> is_pfn_swap_entry() unhappy. Note that swp_entry_t is effectively an >> unsigned long and the maximum swap offset shares that value with the >> swap type. >> >> For example, on an 8 GiB x86 PAE system with a kernel config based on >> Debian 11.5 (-> CONFIG_FLATMEM=y, CONFIG_X86_PAE=y), we will currently fail >> removing migration entries (remove_migration_ptes()), because >> mm/page_vma_mapped.c:check_pte() will fail to identify a PFN match as >> swp_offset_pfn() wrongly masks off PFN bits. For example, >> split_huge_page_to_list()->...->remap_page() will leave migration >> entries in place and continue to unlock the page. >> >> Later, when we stumble over these migration entries (e.g., via >> /proc/self/pagemap), pfn_swap_entry_to_page() will BUG_ON() because >> these migration entries shouldn't exist anymore and the page was >> unlocked. >> >> [ 33.067591] kernel BUG at include/linux/swapops.h:497! >> [ 33.067597] invalid opcode: 0000 [#1] PREEMPT SMP NOPTI >> [ 33.067602] CPU: 3 PID: 742 Comm: cow Tainted: G E 6.1.0-rc8+ #16 >> [ 33.067605] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.0-1.fc36 04/01/2014 >> [ 33.067606] EIP: pagemap_pmd_range+0x644/0x650 >> [ 33.067612] Code: 00 00 00 00 66 90 89 ce b9 00 f0 ff ff e9 ff fb ff ff 89 d8 31 db e8 48 c6 52 00 e9 23 fb ff ff e8 61 83 56 00 e9 b6 fe ff ff <0f> 0b bf 00 f0 ff ff e9 38 fa ff ff 3e 8d 74 26 00 55 89 e5 57 31 >> [ 33.067615] EAX: ee394000 EBX: 00000002 ECX: ee394000 EDX: 00000000 >> [ 33.067617] ESI: c1b0ded4 EDI: 00024a00 EBP: c1b0ddb4 ESP: c1b0dd68 >> [ 33.067619] DS: 007b ES: 007b FS: 00d8 GS: 0033 SS: 0068 EFLAGS: 00010246 >> [ 33.067624] CR0: 80050033 CR2: b7a00000 CR3: 01bbbd20 CR4: 00350ef0 >> [ 33.067625] Call Trace: >> [ 33.067628] ? madvise_free_pte_range+0x720/0x720 >> [ 33.067632] ? smaps_pte_range+0x4b0/0x4b0 >> [ 33.067634] walk_pgd_range+0x325/0x720 >> [ 33.067637] ? mt_find+0x1d6/0x3a0 >> [ 33.067641] ? mt_find+0x1d6/0x3a0 >> [ 33.067643] __walk_page_range+0x164/0x170 >> [ 33.067646] walk_page_range+0xf9/0x170 >> [ 33.067648] ? __kmem_cache_alloc_node+0x2a8/0x340 >> [ 33.067653] pagemap_read+0x124/0x280 >> [ 33.067658] ? default_llseek+0x101/0x160 >> [ 33.067662] ? smaps_account+0x1d0/0x1d0 >> [ 33.067664] vfs_read+0x90/0x290 >> [ 33.067667] ? do_madvise.part.0+0x24b/0x390 >> [ 33.067669] ? debug_smp_processor_id+0x12/0x20 >> [ 33.067673] ksys_pread64+0x58/0x90 >> [ 33.067675] __ia32_sys_ia32_pread64+0x1b/0x20 >> [ 33.067680] __do_fast_syscall_32+0x4c/0xc0 >> [ 33.067683] do_fast_syscall_32+0x29/0x60 >> [ 33.067686] do_SYSENTER_32+0x15/0x20 >> [ 33.067689] entry_SYSENTER_32+0x98/0xf1 >> >> Decrease the indentation level of SWP_PFN_BITS and SWP_PFN_MASK to keep >> it readable and consistent. >> >> Fixes: 0d206b5d2e0d ("mm/swap: add swp_offset_pfn() to fetch PFN from swap entry") >> Cc: Andrew Morton >> Cc: Peter Xu >> Cc: Yang Shi >> Cc: Hugh Dickins >> Cc: Andrea Arcangeli >> Signed-off-by: David Hildenbrand >> --- >> >> v1 -> v2: >> * Rely on sizeof(phys_addr_t) and min_t() instead. >> * Survives my various cross compilations and testing on x86 PAE. > > Good to know it works, thanks a lot. > > Acked-by: Peter Xu > Thanks. I realized that we can simply use min_t(int, instead of min_t(phys_addr_t, because we're only comparing numbers < 64 ... Might look cleaner and less complicated. From e6f0c1099de69a11e643e4d4ee6f470147aa174e Mon Sep 17 00:00:00 2001 From: David Hildenbrand Date: Wed, 7 Dec 2022 21:15:36 +0100 Subject: [PATCH] Fixup: "mm/swap: fix SWP_PFN_BITS with CONFIG_PHYS_ADDR_T_64BIT on 32bit" Let's use "int" for comparison, as we're only comparing numbers < 64. Signed-off-by: David Hildenbrand --- include/linux/swapops.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/include/linux/swapops.h b/include/linux/swapops.h index a70b5c3a68d7..b982dd614572 100644 --- a/include/linux/swapops.h +++ b/include/linux/swapops.h @@ -35,7 +35,7 @@ #ifdef MAX_PHYSMEM_BITS #define SWP_PFN_BITS (MAX_PHYSMEM_BITS - PAGE_SHIFT) #else /* MAX_PHYSMEM_BITS */ -#define SWP_PFN_BITS min_t(phys_addr_t, \ +#define SWP_PFN_BITS min_t(int, \ sizeof(phys_addr_t) * 8 - PAGE_SHIFT, \ SWP_TYPE_SHIFT) #endif /* MAX_PHYSMEM_BITS */ -- 2.38.1 @Andrew, I just cross-compiled and retested with that successfully. -- Thanks, David / dhildenb