From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754725AbdBHPIM (ORCPT ); Wed, 8 Feb 2017 10:08:12 -0500 Received: from resqmta-ch2-03v.sys.comcast.net ([69.252.207.35]:49656 "EHLO resqmta-ch2-03v.sys.comcast.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751913AbdBHPIH (ORCPT ); Wed, 8 Feb 2017 10:08:07 -0500 Date: Wed, 8 Feb 2017 09:06:47 -0600 (CST) From: Christoph Lameter X-X-Sender: cl@east.gentwo.org To: Thomas Gleixner cc: Michal Hocko , Mel Gorman , Vlastimil Babka , Dmitry Vyukov , Tejun Heo , "linux-mm@kvack.org" , LKML , Ingo Molnar , Peter Zijlstra , syzkaller , Andrew Morton Subject: Re: mm: deadlock between get_online_cpus/pcpu_alloc In-Reply-To: Message-ID: References: <2cdef192-1939-d692-1224-8ff7d7ff7203@suse.cz> <20170207102809.awh22urqmfrav5r6@techsingularity.net> <20170207103552.GH5065@dhcp22.suse.cz> <20170207113435.6xthczxt2cx23r4t@techsingularity.net> <20170207114327.GI5065@dhcp22.suse.cz> <20170207123708.GO5065@dhcp22.suse.cz> <20170207135846.usfrn7e4znjhmogn@techsingularity.net> <20170207141911.GR5065@dhcp22.suse.cz> <20170207153459.GV5065@dhcp22.suse.cz> <20170207162224.elnrlgibjegswsgn@techsingularity.net> <20170207164130.GY5065@dhcp22.suse.cz> Content-Type: text/plain; charset=US-ASCII X-CMAE-Envelope: MS4wfErg+bkEiKzwEh3KBzUkIde4yjJOLO+nGsQPGD+Uwn/e2JZeXDxuHk1QcQyBGUv4dHWWrIO2U4y7948iOyDcmps1gxaGduWScqo1BqeMOa/BTrNsgUm+ YAQdOfNAP9WI56ijKfVmcysjTvMwHpG4YWeD0G7yEOmPAUMtYGmD8paeIncR1UO4ZM6gwXakrK4oRIV1SXItrzeLUKIvsOy1HpXBdLuxJO6E4HQ9bJ2ggJVN xsEcnfXXSi/Ny1OA9RtN/BoUjI72W/bRhBaoTphfpdDPog9h7zrnpx4cUBV0Fx5h5k3P2y04uZ3yHhTR4zWqcGlox/NPg/IUK/6zxrB/+ayw8o8e4SugovVY 59zb+VqjSwkGyXBx2E645wj0zHrzqptI9V6ffz4DkTJgwCVC0Xy3wRA+Su2yPrfMW7lMq43wYhiyNqNbaZmHXoduOTC8fHqMfowKHaUZw++Z83zVy97qtadS Lg9+ghyMoUifmYW5BJnhWtUJPSU8byihdUk3UQ== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 7 Feb 2017, Thomas Gleixner wrote: > > Yep. Hotplug events are pretty significant. Using stop_machine_XXXX() etc > > would be advisable and that would avoid the taking of locks and get rid of all the > > ocmplexity, reduce the code size and make the overall system much more > > reliable. > > Huch? stop_machine() is horrible and heavy weight. Don't go there, there > must be simpler solutions than that. Inserting or removing hardware is a heavy process. This would help quite a bit with these issues for loops over active cpus. From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-io0-f199.google.com (mail-io0-f199.google.com [209.85.223.199]) by kanga.kvack.org (Postfix) with ESMTP id 1FA716B0033 for ; Wed, 8 Feb 2017 10:06:52 -0500 (EST) Received: by mail-io0-f199.google.com with SMTP id 101so147817298iom.7 for ; Wed, 08 Feb 2017 07:06:52 -0800 (PST) Received: from resqmta-ch2-08v.sys.comcast.net (resqmta-ch2-08v.sys.comcast.net. [2001:558:fe21:29:69:252:207:40]) by mx.google.com with ESMTPS id q135si14916219iod.130.2017.02.08.07.06.51 for (version=TLS1_2 cipher=ECDHE-RSA-AES128-GCM-SHA256 bits=128/128); Wed, 08 Feb 2017 07:06:51 -0800 (PST) Date: Wed, 8 Feb 2017 09:06:47 -0600 (CST) From: Christoph Lameter Subject: Re: mm: deadlock between get_online_cpus/pcpu_alloc In-Reply-To: Message-ID: References: <2cdef192-1939-d692-1224-8ff7d7ff7203@suse.cz> <20170207102809.awh22urqmfrav5r6@techsingularity.net> <20170207103552.GH5065@dhcp22.suse.cz> <20170207113435.6xthczxt2cx23r4t@techsingularity.net> <20170207114327.GI5065@dhcp22.suse.cz> <20170207123708.GO5065@dhcp22.suse.cz> <20170207135846.usfrn7e4znjhmogn@techsingularity.net> <20170207141911.GR5065@dhcp22.suse.cz> <20170207153459.GV5065@dhcp22.suse.cz> <20170207162224.elnrlgibjegswsgn@techsingularity.net> <20170207164130.GY5065@dhcp22.suse.cz> Content-Type: text/plain; charset=US-ASCII Sender: owner-linux-mm@kvack.org List-ID: To: Thomas Gleixner Cc: Michal Hocko , Mel Gorman , Vlastimil Babka , Dmitry Vyukov , Tejun Heo , "linux-mm@kvack.org" , LKML , Ingo Molnar , Peter Zijlstra , syzkaller , Andrew Morton On Tue, 7 Feb 2017, Thomas Gleixner wrote: > > Yep. Hotplug events are pretty significant. Using stop_machine_XXXX() etc > > would be advisable and that would avoid the taking of locks and get rid of all the > > ocmplexity, reduce the code size and make the overall system much more > > reliable. > > Huch? stop_machine() is horrible and heavy weight. Don't go there, there > must be simpler solutions than that. Inserting or removing hardware is a heavy process. This would help quite a bit with these issues for loops over active cpus. -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org