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 D50E1C43219 for ; Wed, 1 May 2019 16:51:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B007120644 for ; Wed, 1 May 2019 16:51:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726677AbfEAQv6 (ORCPT ); Wed, 1 May 2019 12:51:58 -0400 Received: from foss.arm.com ([217.140.101.70]:33974 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726434AbfEAQv6 (ORCPT ); Wed, 1 May 2019 12:51:58 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.72.51.249]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 48B2880D; Wed, 1 May 2019 09:51:57 -0700 (PDT) Received: from e107155-lin (e107155-lin.cambridge.arm.com [10.1.196.42]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPSA id 35DD13F719; Wed, 1 May 2019 09:51:54 -0700 (PDT) Date: Wed, 1 May 2019 17:51:51 +0100 From: Sudeep Holla To: Oleg Nesterov 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: <20190501165151.GB12498@e107155-lin> References: <20190318104925.16600-1-sudeep.holla@arm.com> <20190318104925.16600-4-sudeep.holla@arm.com> <20190318153321.GA23521@redhat.com> <20190430164413.GA18913@e107155-lin> <20190501155711.GB30235@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190501155711.GB30235@redhat.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, May 01, 2019 at 05:57:11PM +0200, Oleg Nesterov wrote: > 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. > Sorry, but I didn't have any disagreement, I just said I don't understand the usage on all architectures at that moment. > > 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. > OK, it's just x86, then I understand your point. I was looking at all the architectures, sorry for the confusion. > And I see no reason why x86 needs to use TIF_WORK_SYSCALL_ENTRY in > syscall_trace_enter(). > Agreed -- Regards, Sudeep