From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030868AbeEXQZZ (ORCPT ); Thu, 24 May 2018 12:25:25 -0400 Received: from out02.mta.xmission.com ([166.70.13.232]:42806 "EHLO out02.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1030515AbeEXQZY (ORCPT ); Thu, 24 May 2018 12:25:24 -0400 From: ebiederm@xmission.com (Eric W. Biederman) To: Sebastian Andrzej Siewior Cc: linux-kernel@vger.kernel.org, Miklos Szeredi , Oleg Nesterov , Thomas Gleixner References: <20180524143629.2ofsg7mhjixr5pnm@linutronix.de> Date: Thu, 24 May 2018 11:25:14 -0500 In-Reply-To: <20180524143629.2ofsg7mhjixr5pnm@linutronix.de> (Sebastian Andrzej Siewior's message of "Thu, 24 May 2018 16:36:30 +0200") Message-ID: <87wovt3tsl.fsf@xmission.com> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/25.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1fLt3K-0002PY-Ca;;;mid=<87wovt3tsl.fsf@xmission.com>;;;hst=in01.mta.xmission.com;;;ip=97.119.174.25;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX18qznuTPF2Iig+MAodK9IxCtuaN7FliHLY= X-SA-Exim-Connect-IP: 97.119.174.25 X-SA-Exim-Mail-From: ebiederm@xmission.com X-Spam-Report: * -1.0 ALL_TRUSTED Passed through trusted hosts only via SMTP * 0.0 T_TM2_M_HEADER_IN_MSG BODY: No description available. * 0.8 BAYES_50 BODY: Bayes spam probability is 40 to 60% * [score: 0.5000] * -0.0 DCC_CHECK_NEGATIVE Not listed in DCC * [sa05 1397; Body=1 Fuz1=1 Fuz2=1] X-Spam-DCC: XMission; sa05 1397; Body=1 Fuz1=1 Fuz2=1 X-Spam-Combo: ;Sebastian Andrzej Siewior X-Spam-Relay-Country: X-Spam-Timing: total 301 ms - load_scoreonly_sql: 0.05 (0.0%), signal_user_changed: 3.2 (1.1%), b_tie_ro: 2.2 (0.7%), parse: 1.32 (0.4%), extract_message_metadata: 21 (7.0%), get_uri_detail_list: 2.4 (0.8%), tests_pri_-1000: 11 (3.8%), tests_pri_-950: 1.68 (0.6%), tests_pri_-900: 1.33 (0.4%), tests_pri_-400: 22 (7.3%), check_bayes: 21 (6.9%), b_tokenize: 8 (2.6%), b_tok_get_all: 6 (1.9%), b_comp_prob: 2.4 (0.8%), b_tok_touch_all: 2.7 (0.9%), b_finish: 0.72 (0.2%), tests_pri_0: 232 (76.9%), check_dkim_signature: 0.60 (0.2%), check_dkim_adsp: 3.3 (1.1%), tests_pri_500: 3.5 (1.2%), rewrite_mail: 0.00 (0.0%) Subject: Re: [PATCH] signal: Revert ptrace preempt magic X-Spam-Flag: No X-SA-Exim-Version: 4.2.1 (built Thu, 05 May 2016 13:38:54 -0600) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Sebastian Andrzej Siewior writes: > From: Thomas Gleixner > > Upstream commit '53da1d9456fe7f8 fix ptrace slowness' is nothing more > than a bandaid around the ptrace design trainwreck. It's not a > correctness issue, it's merily a cosmetic bandaid. This patch comes with no justification or reason to remove the ``cosmetic bandaid''. The description in 53da1d9456fe ("fix ptrace slowness") is quite persuasive that there is a real world issue. So while this may be a good idea to remove this. I don't see any description of testing to indicate this won't cause uml to regresssion. Nor do I see any compelling reason except code tidiness to remove this. As such until adequate descriptions can be provideded. Nacked-by: "Eric W. Biederman" > Signed-off-by: Thomas Gleixner > Signed-off-by: Sebastian Andrzej Siewior > --- > kernel/signal.c | 8 -------- > 1 file changed, 8 deletions(-) > > --- a/kernel/signal.c > +++ b/kernel/signal.c > @@ -1876,15 +1876,7 @@ static void ptrace_stop(int exit_code, i > if (gstop_done && ptrace_reparented(current)) > do_notify_parent_cldstop(current, false, why); > > - /* > - * Don't want to allow preemption here, because > - * sys_ptrace() needs this task to be inactive. > - * > - * XXX: implement read_unlock_no_resched(). > - */ > - preempt_disable(); > read_unlock(&tasklist_lock); > - preempt_enable_no_resched(); > freezable_schedule(); > } else { > /*