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=-2.5 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, MAILING_LIST_MULTI,SPF_PASS,USER_AGENT_MUTT autolearn=ham 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 A9098C43219 for ; Wed, 1 May 2019 15:57:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 826E82085A for ; Wed, 1 May 2019 15:57:20 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726586AbfEAP5T (ORCPT ); Wed, 1 May 2019 11:57:19 -0400 Received: from mx1.redhat.com ([209.132.183.28]:57680 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726388AbfEAP5S (ORCPT ); Wed, 1 May 2019 11:57:18 -0400 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mx1.redhat.com (Postfix) with ESMTPS id 86BC8C053B34; Wed, 1 May 2019 15:57:18 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.43.17.159]) by smtp.corp.redhat.com (Postfix) with SMTP id 83E2A1001E95; Wed, 1 May 2019 15:57:14 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Wed, 1 May 2019 17:57:16 +0200 (CEST) Date: Wed, 1 May 2019 17:57:11 +0200 From: Oleg Nesterov To: Sudeep Holla Cc: x86@kernel.org, linux-arm-kernel@lists.infradead.org, linux-kernel@vger.kernel.org, linuxppc-dev@lists.ozlabs.org, Catalin Marinas , Will Deacon , Paul Mackerras , Michael Ellerman , Thomas Gleixner , Ingo Molnar , Richard Weinberger , jdike@addtoit.com, Steve Capper , Haibo Xu , Bin Lu , Andy Lutomirski , Borislav Petkov Subject: Re: [PATCH v2 3/6] x86: clean up _TIF_SYSCALL_EMU handling using ptrace_syscall_enter hook Message-ID: <20190501155711.GB30235@redhat.com> References: <20190318104925.16600-1-sudeep.holla@arm.com> <20190318104925.16600-4-sudeep.holla@arm.com> <20190318153321.GA23521@redhat.com> <20190430164413.GA18913@e107155-lin> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190430164413.GA18913@e107155-lin> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 X-Greylist: Sender IP whitelisted, not delayed by milter-greylist-4.5.16 (mx1.redhat.com [10.5.110.31]); Wed, 01 May 2019 15:57:18 +0000 (UTC) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 04/30, Sudeep Holla wrote: > > On Mon, Mar 18, 2019 at 04:33:22PM +0100, Oleg Nesterov wrote: > > > > And it seems that _TIF_WORK_SYSCALL_ENTRY needs some cleanups too... We don't need > > "& _TIF_WORK_SYSCALL_ENTRY" in syscall_trace_enter, and _TIF_WORK_SYSCALL_ENTRY > > should not include _TIF_NOHZ? > > > > I was about to post the updated version and checked this to make sure I have > covered everything or not. I had missed the above comment. All architectures > have _TIF_NOHZ in their mask that they check to do work. And from x86, I read > "...syscall_trace_enter(). Also includes TIF_NOHZ for enter_from_user_mode()" > So I don't understand why _TIF_NOHZ needs to be dropped. I have already forgot this discussion... But after I glanced at this code again I still think the same, and I don't understand why do you disagree. > Also if we need to drop, we can address that separately examining all archs. Sure, and I was only talking about x86. We can keep TIF_NOHZ and even set_tsk_thread_flag(TIF_NOHZ) in context_tracking_cpu_set() if some arch needs this but remove TIF_NOHZ from TIF_WORK_SYSCALL_ENTRY in arch/x86/include/asm/thread_info.h, afaics this shouldn't make any difference. And I see no reason why x86 needs to use TIF_WORK_SYSCALL_ENTRY in syscall_trace_enter(). Oleg.