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 3F5FFC433EF for ; Tue, 7 Jun 2022 15:27:34 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1344052AbiFGP1c (ORCPT ); Tue, 7 Jun 2022 11:27:32 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41638 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1344031AbiFGP10 (ORCPT ); Tue, 7 Jun 2022 11:27:26 -0400 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.133.124]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 4AF2135243 for ; Tue, 7 Jun 2022 08:27:24 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1654615643; 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=j2QP74kmyLRjPfaslomjwazE8bxfaKWf8AzgM5WImZE=; b=QnAPkHHbMeyjIPK2YmKCjUQbyw+bebTItkhXqjm6b3gVPrAhD6DMt/3Su64ZUnoDTvGVd8 9K0hnmHB8kr6OBiOubTHUhBNpsc0XjslSiAucl7mk8WoDuVE+EpwtDV+6Ni7t/LDN2eIzc JnY7+RD2b8w/viRYUqRbkH6BN/70dwk= Received: from mimecast-mx02.redhat.com (mimecast-mx02.redhat.com [66.187.233.88]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id us-mta-470-ppflYsfZM8qOHDXTPBRCHg-1; Tue, 07 Jun 2022 11:27:20 -0400 X-MC-Unique: ppflYsfZM8qOHDXTPBRCHg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.rdu2.redhat.com [10.11.54.8]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx02.redhat.com (Postfix) with ESMTPS id 911C3968EEB; Tue, 7 Jun 2022 15:27:18 +0000 (UTC) Received: from dhcp-27-174.brq.redhat.com (unknown [10.40.192.101]) by smtp.corp.redhat.com (Postfix) with SMTP id DF67DC27E92; Tue, 7 Jun 2022 15:26:58 +0000 (UTC) Received: by dhcp-27-174.brq.redhat.com (nbSMTP-1.00) for uid 1000 oleg@redhat.com; Tue, 7 Jun 2022 17:27:15 +0200 (CEST) Date: Tue, 7 Jun 2022 17:26:54 +0200 From: Oleg Nesterov To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org, Robert OCallahan , Kyle Huey , Richard Henderson , Ivan Kokshaysky , Matt Turner , Jason Wessel , Daniel Thompson , Douglas Anderson , Douglas Miller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras Subject: Re: [PATCH 07/16] signal: Wake up the designated parent Message-ID: <20220607152627.GA10192@redhat.com> References: <871qwq5ucx.fsf_-_@email.froward.int.ebiederm.org> <20220518225355.784371-7-ebiederm@xmission.com> <20220524132553.GD14347@redhat.com> <20220524162808.GF14347@redhat.com> <20220525142845.GA2687@redhat.com> <87a6ap30lh.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87a6ap30lh.fsf@email.froward.int.ebiederm.org> User-Agent: Mutt/1.5.24 (2015-08-30) X-Scanned-By: MIMEDefang 2.85 on 10.11.54.8 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 06/06, Eric W. Biederman wrote: > > Which if I have had enough sleep reduces this patch to just: > > diff --git a/kernel/exit.c b/kernel/exit.c > index f072959fcab7..c8156366b722 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1431,8 +1431,10 @@ static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, > if (!eligible_pid(wo, p)) > return 0; > > - if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) > - return 0; > + if ((wo->wo_flags & __WNOTHREAD) && > + (wait->private != p->parent) && > + (wait->private != p->real_parent)) > + return 0; > > return default_wake_function(wait, mode, sync, key); > } > > > I think that solves the issue without missing wake-ups without adding > any more. Agreed, and looks much simpler. > For the same set of reasons it looks like the __wake_up_parent in > __ptrace_detach is just simply dead code. I don't think there is a case > where when !ptrace_reparented the thread that is the real_parent can > sleep in do_wait when the thread that was calling ptrace could not. Yes... this doesn't really differ from the case when one thread reaps a natural child and another thread sleep in do_wait(). > That needs a very close look to confirm. Yes. Oleg. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nyb79-008HIi-4E for linux-um@lists.infradead.org; Tue, 07 Jun 2022 15:27:28 +0000 Date: Tue, 7 Jun 2022 17:26:54 +0200 From: Oleg Nesterov Subject: Re: [PATCH 07/16] signal: Wake up the designated parent Message-ID: <20220607152627.GA10192@redhat.com> References: <871qwq5ucx.fsf_-_@email.froward.int.ebiederm.org> <20220518225355.784371-7-ebiederm@xmission.com> <20220524132553.GD14347@redhat.com> <20220524162808.GF14347@redhat.com> <20220525142845.GA2687@redhat.com> <87a6ap30lh.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: <87a6ap30lh.fsf@email.froward.int.ebiederm.org> List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-um" Errors-To: linux-um-bounces+geert=linux-m68k.org@lists.infradead.org To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org, Robert OCallahan , Kyle Huey , Richard Henderson , Ivan Kokshaysky , Matt Turner , Jason Wessel , Daniel Thompson , Douglas Anderson , Douglas Miller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras On 06/06, Eric W. Biederman wrote: > > Which if I have had enough sleep reduces this patch to just: > > diff --git a/kernel/exit.c b/kernel/exit.c > index f072959fcab7..c8156366b722 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1431,8 +1431,10 @@ static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, > if (!eligible_pid(wo, p)) > return 0; > > - if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) > - return 0; > + if ((wo->wo_flags & __WNOTHREAD) && > + (wait->private != p->parent) && > + (wait->private != p->real_parent)) > + return 0; > > return default_wake_function(wait, mode, sync, key); > } > > > I think that solves the issue without missing wake-ups without adding > any more. Agreed, and looks much simpler. > For the same set of reasons it looks like the __wake_up_parent in > __ptrace_detach is just simply dead code. I don't think there is a case > where when !ptrace_reparented the thread that is the real_parent can > sleep in do_wait when the thread that was calling ptrace could not. Yes... this doesn't really differ from the case when one thread reaps a natural child and another thread sleep in do_wait(). > That needs a very close look to confirm. Yes. Oleg. _______________________________________________ linux-um mailing list linux-um@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-um From mboxrd@z Thu Jan 1 00:00:00 1970 From: Oleg Nesterov Date: Tue, 07 Jun 2022 15:26:54 +0000 Subject: Re: [PATCH 07/16] signal: Wake up the designated parent Message-Id: <20220607152627.GA10192@redhat.com> List-Id: References: <871qwq5ucx.fsf_-_@email.froward.int.ebiederm.org> <20220518225355.784371-7-ebiederm@xmission.com> <20220524132553.GD14347@redhat.com> <20220524162808.GF14347@redhat.com> <20220525142845.GA2687@redhat.com> <87a6ap30lh.fsf@email.froward.int.ebiederm.org> In-Reply-To: <87a6ap30lh.fsf@email.froward.int.ebiederm.org> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: "Eric W. Biederman" Cc: linux-kernel@vger.kernel.org, rjw@rjwysocki.net, mingo@kernel.org, vincent.guittot@linaro.org, dietmar.eggemann@arm.com, rostedt@goodmis.org, mgorman@suse.de, bigeasy@linutronix.de, Will Deacon , tj@kernel.org, linux-pm@vger.kernel.org, Peter Zijlstra , Richard Weinberger , Anton Ivanov , Johannes Berg , linux-um@lists.infradead.org, Chris Zankel , Max Filippov , linux-xtensa@linux-xtensa.org, Kees Cook , Jann Horn , linux-ia64@vger.kernel.org, Robert OCallahan , Kyle Huey , Richard Henderson , Ivan Kokshaysky , Matt Turner , Jason Wessel , Daniel Thompson , Douglas Anderson , Douglas Miller , Michael Ellerman , Benjamin Herrenschmidt , Paul Mackerras On 06/06, Eric W. Biederman wrote: > > Which if I have had enough sleep reduces this patch to just: > > diff --git a/kernel/exit.c b/kernel/exit.c > index f072959fcab7..c8156366b722 100644 > --- a/kernel/exit.c > +++ b/kernel/exit.c > @@ -1431,8 +1431,10 @@ static int child_wait_callback(wait_queue_entry_t *wait, unsigned mode, > if (!eligible_pid(wo, p)) > return 0; > > - if ((wo->wo_flags & __WNOTHREAD) && wait->private != p->parent) > - return 0; > + if ((wo->wo_flags & __WNOTHREAD) && > + (wait->private != p->parent) && > + (wait->private != p->real_parent)) > + return 0; > > return default_wake_function(wait, mode, sync, key); > } > > > I think that solves the issue without missing wake-ups without adding > any more. Agreed, and looks much simpler. > For the same set of reasons it looks like the __wake_up_parent in > __ptrace_detach is just simply dead code. I don't think there is a case > where when !ptrace_reparented the thread that is the real_parent can > sleep in do_wait when the thread that was calling ptrace could not. Yes... this doesn't really differ from the case when one thread reaps a natural child and another thread sleep in do_wait(). > That needs a very close look to confirm. Yes. Oleg.