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 B473CCDB482 for ; Tue, 17 Oct 2023 09:57:23 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id 2C24F8D0109; Tue, 17 Oct 2023 05:57:23 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 2730E8D000C; Tue, 17 Oct 2023 05:57:23 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 162978D0109; Tue, 17 Oct 2023 05:57:23 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 092EE8D000C for ; Tue, 17 Oct 2023 05:57:23 -0400 (EDT) Received: from smtpin20.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay06.hostedemail.com (Postfix) with ESMTP id CD505B63E9 for ; Tue, 17 Oct 2023 09:57:22 +0000 (UTC) X-FDA: 81354500724.20.CA2A891 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by imf30.hostedemail.com (Postfix) with ESMTP id 0D9CD80013 for ; Tue, 17 Oct 2023 09:57:20 +0000 (UTC) Authentication-Results: imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=CBgxSfB2; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of ardb@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=ardb@kernel.org ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=hostedemail.com; s=arc-20220608; t=1697536641; 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: in-reply-to:in-reply-to:references:references:dkim-signature; bh=fCybuev8u2mLHJZo/DgPK9PSt1vqOPKFa1SF6X2U518=; b=2x0FSZ8HlHxqTUZ4/IJXMimR+7vnoeRjyaBnLcqaU7yGb0+aNda+s115sUuKnKjMuko2WJ 5gDjulnfpGAd3EaVK4vFFbw3xD+fiMEUiAVpWl//1uyWG8qLpVKBbRdzPvet6MEA+KVLLU k5cdvUQZ+3u2xZsgNGbEkXToh3IGbiA= ARC-Authentication-Results: i=1; imf30.hostedemail.com; dkim=pass header.d=kernel.org header.s=k20201202 header.b=CBgxSfB2; dmarc=pass (policy=none) header.from=kernel.org; spf=pass (imf30.hostedemail.com: domain of ardb@kernel.org designates 139.178.84.217 as permitted sender) smtp.mailfrom=ardb@kernel.org ARC-Seal: i=1; s=arc-20220608; d=hostedemail.com; t=1697536641; a=rsa-sha256; cv=none; b=AysgUteqvRkOhynqhVRxyNCboikfNCjTA6uhJsE1SlN4Li01/tO/h3tOrdfF6rRMIvKpbs CrPQHV1Y86La04xCRyePmsXe3mXeMx/iEp3NZ295DlrzbUvKQpIu0ouGvq2yzSEgqnLKuB cLJLS9/4gFW1OgUh6C6TyfmME9S0nRM= Received: from smtp.kernel.org (transwarp.subspace.kernel.org [100.75.92.58]) by dfw.source.kernel.org (Postfix) with ESMTP id 22A416126D for ; Tue, 17 Oct 2023 09:57:20 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C82D7C433C8 for ; Tue, 17 Oct 2023 09:57:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1697536639; bh=sKwYVnqhSSrwqp7PC9H2TY6yCD+XS2CditWC5vXqB+4=; h=References:In-Reply-To:From:Date:Subject:To:Cc:From; b=CBgxSfB237rqRI9/lYgZglglsdpwEqcW7F0KqpbEKc15ZDg3CHRwqrxtl3WbD5ts4 LY0MgzE3g7ZTeyfPZD/4h4w/Rv4vAfcBvUDWw8saPVGVzAXrGHmIWfpz/EM3KWtgoZ HWLGHI6ZYI6GgwzdrxSHSjMgFxmiizLgfjvp5hatThd1AVR6zR/bzp/sQC9Qz7G8ci KWvhOx0NpS+F8kmwW13nNN2nzW3e26WHAHh8+CYvo4Kp2kY7D+4RQo0REXfuvCsYOW 6DT9gvrsG8IOFI5PoiLbbzs7hClUKkkCoOegLl8io3zB/EUSZoXTwuevn8Pqtwv4CN vIc7qpt0hH4aA== Received: by mail-lj1-f171.google.com with SMTP id 38308e7fff4ca-2c504a5e1deso60349041fa.2 for ; Tue, 17 Oct 2023 02:57:19 -0700 (PDT) X-Gm-Message-State: AOJu0YwlpdDqBcodaTVH7iT+jszomP62QNMXshdlWjaOzpWKAnEy7KLX xYFOWaLQlXuzvX6Uj/i39UMn7UUGsp95jgP/zJE= X-Google-Smtp-Source: AGHT+IERIod7g0rUfYOG5lQ+1VdU8HkDDU1bvoLEdkPVYMpGfqbElsDImze8vsj7zXXRxTLmhlOFqN7ybSsC3FaHCv0= X-Received: by 2002:a2e:be12:0:b0:2bd:133c:2d71 with SMTP id z18-20020a2ebe12000000b002bd133c2d71mr1124282ljq.52.1697536638036; Tue, 17 Oct 2023 02:57:18 -0700 (PDT) MIME-Version: 1.0 References: <20231016163122.12855-1-kirill.shutemov@linux.intel.com> <20231016213932.6cscnn6tsnzsnvmf@box.shutemov.name> <20231017094403.g6laxp2c3vwzt2sw@box.shutemov.name> In-Reply-To: <20231017094403.g6laxp2c3vwzt2sw@box.shutemov.name> From: Ard Biesheuvel Date: Tue, 17 Oct 2023 11:57:06 +0200 X-Gmail-Original-Message-ID: Message-ID: Subject: Re: [PATCHv2] efi/unaccepted: Fix soft lockups caused by parallel memory acceptance To: "Kirill A. Shutemov" Cc: Matthew Wilcox , Borislav Petkov , Andy Lutomirski , Dave Hansen , Sean Christopherson , Andrew Morton , Joerg Roedel , Andi Kleen , Kuppuswamy Sathyanarayanan , David Rientjes , Vlastimil Babka , Tom Lendacky , Thomas Gleixner , Peter Zijlstra , Paolo Bonzini , Ingo Molnar , Dario Faggioli , Mike Rapoport , David Hildenbrand , Mel Gorman , marcelo.cerri@canonical.com, tim.gardner@canonical.com, philip.cox@canonical.com, aarcange@redhat.com, peterx@redhat.com, x86@kernel.org, linux-mm@kvack.org, linux-coco@lists.linux.dev, linux-efi@vger.kernel.org, linux-kernel@vger.kernel.org, stable@kernel.org, Nikolay Borisov Content-Type: text/plain; charset="UTF-8" X-Rspamd-Queue-Id: 0D9CD80013 X-Rspam-User: X-Rspamd-Server: rspam02 X-Stat-Signature: r86dudx6a441j7sx4d1m493wigakerox X-HE-Tag: 1697536640-925898 X-HE-Meta: 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 3WmZSpGa +plhNHkP2PrVs+Qc1uLckzj2QRVkOjD073SdFXz8ckfgYfqHvnb83RiqENLJKAkbIWYLC4SZDc/5Gx6i1Dkn1LTaAAeEaPIQIqKVfSUO3zLa2egtbUUfhUNb5hGKXIv28ytL/X216n4rcUoa1/erLrvLDjwUfcaVY0IV4H62rNg7jku81P1WLKuvGUumg+ENjMQKhfOW1WFLyEqNwg6Xdb05bT290UIZXAL1gk3mRc3qUpRnZgc334Df4og== 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 Tue, 17 Oct 2023 at 11:44, Kirill A. Shutemov wrote: > > On Tue, Oct 17, 2023 at 09:42:13AM +0200, Ard Biesheuvel wrote: > > On Mon, 16 Oct 2023 at 23:39, Kirill A. Shutemov > > wrote: > > > > > > On Mon, Oct 16, 2023 at 06:55:41PM +0100, Matthew Wilcox wrote: > > > > On Mon, Oct 16, 2023 at 07:31:22PM +0300, Kirill A. Shutemov wrote: > > > > > v2: > > > > > - Fix deadlock (Vlastimil); > > > > > - Fix comments (Vlastimil); > > > > > - s/cond_resched()/cpu_relax()/ -- cond_resched() cannot be called > > > > > from atomic context; > > > > > > > > Isn't there an implicit cpu_relax() while we're spinning? Does this > > > > really accomplish anything? > > > > > > You are right. It is useless. I will drop it in v3. > > > > > > > I can drop that bit when applying the patch. > > > > One question I have is whether the sequence > > > > spin_lock_irqsave(&unaccepted_memory_lock, flags); > > ... > > spin_unlock(&unaccepted_memory_lock); > > arch_accept_memory(phys_start, phys_end); > > spin_lock(&unaccepted_memory_lock); > > ... > > spin_unlock_irqrestore(&unaccepted_memory_lock, flags); > > > > is considered sound and is supported by all architectures? > > I am not an locking expert and only tested it on x86. But what potential > issue do you see? > Not sure. It just looks slightly out of place, and I am curious whether all architectures tolerate this asymmetric use.