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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id EDCCAC433F5 for ; Fri, 22 Apr 2022 22:21:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232925AbiDVWYX (ORCPT ); Fri, 22 Apr 2022 18:24:23 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:39920 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232981AbiDVWWk (ORCPT ); Fri, 22 Apr 2022 18:22:40 -0400 Received: from galois.linutronix.de (Galois.linutronix.de [193.142.43.55]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 239F133B1EB; Fri, 22 Apr 2022 14:13:53 -0700 (PDT) Date: Fri, 22 Apr 2022 23:13:50 +0200 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020; t=1650662031; 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: in-reply-to:in-reply-to:references:references; bh=96/sG4U1PMahw+5F2cvDWRLKP9CkFv2MeGAwdZV08Lo=; b=ANh7OX8dy7UDbQE5tUInn+33OnlAEFzf2qzE0jCgaNtnwimp1tja/4cy43aHj8733bssAs 1t6UCwG3hHS2yBSn1x+B8KFA8LuthbsSKj0mwq6uv4UhCpkqwGD3ezC+guhJRCc1BOoiu4 4kq6u33r744ppk4w7zTzheEfqaKOVUb/oxmgd60GSOAboABQXmNq4vZ6gKN3eff8c4azGe USicNG7lxkrk6Hq8QPzCjhc8FkUpWc0oGSjNdA6tagIApvuB2tm2glYrNq3lIqJhDucLFF mZt1ywOy5kbVVWHpK04iBZwMd0vSKVy2OIew1szGwt+g3nOT3VL/edqBe0+kRQ== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1650662031; 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: in-reply-to:in-reply-to:references:references; bh=96/sG4U1PMahw+5F2cvDWRLKP9CkFv2MeGAwdZV08Lo=; b=2fqKG24m2+QfMM/URFklauogxCi4xCU6UwTmlOdXwzuDKiG6RVeO8XwDQuGfIwGvRkPwH5 XfxCrWoRXUEZGNCA== From: Sebastian Andrzej Siewior To: "Eric W. Biederman" Cc: Peter Zijlstra , rjw@rjwysocki.net, oleg@redhat.com, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, Will Deacon , linux-kernel@vger.kernel.org, tj@kernel.org, linux-pm@vger.kernel.org Subject: Re: [PATCH v2 0/5] ptrace-vs-PREEMPT_RT and freezer rewrite Message-ID: References: <20220421150248.667412396@infradead.org> <878rrxnd48.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline In-Reply-To: <878rrxnd48.fsf@email.froward.int.ebiederm.org> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2022-04-22 14:15:35 [-0500], Eric W. Biederman wrote: > Sebastian Andrzej Siewior writes: > > > On 2022-04-21 17:02:48 [+0200], Peter Zijlstra wrote: > >> Find here a new posting of the ptrace and freezer patches :-) > >> > >> The majority of the changes are in patch 2, which with much feedback from Oleg > >> and Eric has changed lots. > >> > >> I'm hoping we're converging on something agreeable. > > > > I tested this under RT (had to remove the preempt-disable section in > > ptrace_stop()) with ssdd [0]. It forks a few tasks and then > > PTRACE_SINGLESTEPs them for a few iterations. > > Out of curiosity why did you need to remove the preempt_disable section > on PREEMPT_RT? It should have lasted for just a moment until schedule > was called. within that section spinlock_t locks are acquired. These locks are sleeping locks on PREEMPT_RT and must not be acquired within a preempt-disable section. (A spinlock_t lock does not disable preemption on PREEMPT_RT.) > Eric Sebastian