From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752690AbeFAPCW (ORCPT ); Fri, 1 Jun 2018 11:02:22 -0400 Received: from mx2.suse.de ([195.135.220.15]:46156 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751378AbeFAPCV (ORCPT ); Fri, 1 Jun 2018 11:02:21 -0400 Date: Fri, 1 Jun 2018 17:02:19 +0200 From: Michal Hocko To: "Eric W. Biederman" Cc: Kirill Tkhai , akpm@linux-foundation.org, peterz@infradead.org, oleg@redhat.com, viro@zeniv.linux.org.uk, mingo@kernel.org, paulmck@linux.vnet.ibm.com, keescook@chromium.org, riel@redhat.com, tglx@linutronix.de, kirill.shutemov@linux.intel.com, marcos.souza.org@gmail.com, hoeun.ryu@gmail.com, pasha.tatashin@oracle.com, gs051095@gmail.com, dhowells@redhat.com, rppt@linux.vnet.ibm.com, linux-kernel@vger.kernel.org Subject: Re: [PATCH 0/4] exit: Make unlikely case in mm_update_next_owner() more scalable Message-ID: <20180601150219.GG15278@dhcp22.suse.cz> References: <152473763015.29458.1131542311542381803.stgit@localhost.localdomain> <20180426130700.GP17484@dhcp22.suse.cz> <877enj9uwf.fsf@xmission.com> <20180601135725.GE15278@dhcp22.suse.cz> <87a7sey3ud.fsf@xmission.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <87a7sey3ud.fsf@xmission.com> User-Agent: Mutt/1.9.5 (2018-04-13) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri 01-06-18 09:32:42, Eric W. Biederman wrote: > Michal Hocko writes: [...] > > Group leader exiting early without tearing down the whole thread > > group should be quite rare as well. No question that somebody might do > > that on purpose though... > > The group leader exiting early is a completely legitimate and reasonable > thing to do, even if it is rare. I am not saying it isn't legitimate. But the most common case is the main thread waiting for its threads or calling exit which would tear the whole group down. Is there any easy way to achieve this other than tkill to group leader? Calling exit(3) from the leader performs group exit IIRC. I am not arguing this is non-issue. And it certainly is a problem once somebody wants to be nasty... I was more interested how often this really happens for sane workloads. -- Michal Hocko SUSE Labs