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 X-Spam-Level: X-Spam-Status: No, score=-2.4 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 autolearn=no autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id AAE98C43331 for ; Sat, 4 Apr 2020 02:11:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 6EB7220737 for ; Sat, 4 Apr 2020 02:11:28 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="dzUzA4z4" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726328AbgDDCCU (ORCPT ); Fri, 3 Apr 2020 22:02:20 -0400 Received: from us-smtp-delivery-1.mimecast.com ([205.139.110.120]:33960 "EHLO us-smtp-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726186AbgDDCCT (ORCPT ); Fri, 3 Apr 2020 22:02:19 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1585965738; 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=SEySp0igGGDaXwATMDuOfmSBnZ6a+w2LGLwT++JWohM=; b=dzUzA4z4/azREAQtCMyj04AVnyqw6hRKWK5HbLySvy7rvPTKO8yn6qFp8YM0k+ErbwJuDW jFkeGl1yK8DPxWeZ+V/gBzyjKRYBJPLTUmZFKcZZBeP81cGQcoK1Epp+0HrEqGs7bJ3Q1G EfXfYJNJSTXkj9lXwUtulIELDoDidWk= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-62-YclbKtIJPh2hNF82t5852Q-1; Fri, 03 Apr 2020 22:02:14 -0400 X-MC-Unique: YclbKtIJPh2hNF82t5852Q-1 Received: from smtp.corp.redhat.com (int-mx03.intmail.prod.int.phx2.redhat.com [10.5.11.13]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 160CC13F6; Sat, 4 Apr 2020 02:02:13 +0000 (UTC) Received: from llong.remote.csb (ovpn-118-94.rdu2.redhat.com [10.10.118.94]) by smtp.corp.redhat.com (Postfix) with ESMTP id 1F71999E1D; Sat, 4 Apr 2020 02:02:12 +0000 (UTC) Subject: Re: [GIT PULL] Please pull proc and exec work for 5.7-rc1 To: Linus Torvalds Cc: "Eric W. Biederman" , Ingo Molnar , Will Deacon , Bernd Edlinger , Linux Kernel Mailing List , Alexey Gladkov References: <87blobnq02.fsf@x220.int.ebiederm.org> <87lfnda3w3.fsf@x220.int.ebiederm.org> <328f5ad3-f8b3-09b9-f2f7-b6dae0137542@redhat.com> <86aa9fc6-6ac9-a0c2-3e1d-a602ef16d873@redhat.com> From: Waiman Long Organization: Red Hat Message-ID: <5c04cc6d-ec44-b840-071d-248ac81a0f91@redhat.com> Date: Fri, 3 Apr 2020 22:02:11 -0400 User-Agent: Mozilla/5.0 (X11; Linux x86_64; rv:60.0) Gecko/20100101 Thunderbird/60.7.2 MIME-Version: 1.0 In-Reply-To: Content-Type: text/plain; charset=utf-8 Content-Language: en-US X-Scanned-By: MIMEDefang 2.79 on 10.5.11.13 Content-Transfer-Encoding: quoted-printable Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 4/3/20 9:30 PM, Linus Torvalds wrote: > On Fri, Apr 3, 2020 at 4:23 PM Waiman Long wrote: >> Alternatively, we could assert that only one reader can do the upgrade >> and do a WARN_ON_ONCE() if multiple concurrent upgrade attempts is det= ected. > Ack, that would be best. > > [ And since I'm not on mobile any more, and my html email got thrown > out by the list, I'll just repeat that by "static choice" I mean "no > runtime decisions or flags": code that needs the unfair behavior would > use a special unfair function ] > > Linus > Got it. So in term of priority, my current thinking is =C2=A0=C2=A0=C2=A0 upgrading unfair reader > unfair reader > reader/write= r A higher priority locker will block other lockers from acquiring the lock= . Thought? Cheers, Longman