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 X-Spam-Level: X-Spam-Status: No, score=-8.6 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_HELO_NONE,SPF_PASS,USER_AGENT_MUTT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id E7E18C31E54 for ; Mon, 17 Jun 2019 07:47:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B08B321E6D for ; Mon, 17 Jun 2019 07:47:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1560757639; bh=h/znqrcnYEBWI/UhxGutMPFkTJG29CYIuRKIvGd+Uow=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=J4tX73mnw5vDVKGvhlQAJ7IXoxrliv88g/jDeNoSVa6sEy3NBmEpw9l/PYkuuyL7i DAoefA/QIxKpvD4NlSK/n5J+/ZuRCfOIJzaGRH65JuljVTUOchueH4mtN97Ys+xEjt l3jOCuBp7atu8ru+IRNsRkTWL65dSDylOWBdEDzI= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727420AbfFQHrS (ORCPT ); Mon, 17 Jun 2019 03:47:18 -0400 Received: from mx2.suse.de ([195.135.220.15]:39204 "EHLO mx1.suse.de" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726028AbfFQHrS (ORCPT ); Mon, 17 Jun 2019 03:47:18 -0400 X-Virus-Scanned: by amavisd-new at test-mx.suse.de Received: from relay2.suse.de (unknown [195.135.220.254]) by mx1.suse.de (Postfix) with ESMTP id EEB10AFC3; Mon, 17 Jun 2019 07:47:16 +0000 (UTC) Date: Mon, 17 Jun 2019 09:47:15 +0200 From: Michal Hocko To: Alastair D'Silva Cc: alastair@d-silva.org, Arun KS , Mukesh Ojha , Logan Gunthorpe , Wei Yang , Peter Zijlstra , Ingo Molnar , linux-mm@kvack.org, Qian Cai , Thomas Gleixner , Andrew Morton , Mike Rapoport , Baoquan He , David Hildenbrand , Josh Poimboeuf , Pavel Tatashin , Juergen Gross , Oscar Salvador , Jiri Kosina , linux-kernel@vger.kernel.org Subject: Re: [PATCH 4/5] mm/hotplug: Avoid RCU stalls when removing large amounts of memory Message-ID: <20190617074715.GE30420@dhcp22.suse.cz> References: <20190617043635.13201-1-alastair@au1.ibm.com> <20190617043635.13201-5-alastair@au1.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190617043635.13201-5-alastair@au1.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon 17-06-19 14:36:30, Alastair D'Silva wrote: > From: Alastair D'Silva > > When removing sufficiently large amounts of memory, we trigger RCU stall > detection. By periodically calling cond_resched(), we avoid bogus stall > warnings. > > Signed-off-by: Alastair D'Silva > --- > mm/memory_hotplug.c | 3 +++ > 1 file changed, 3 insertions(+) > > diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c > index e096c987d261..382b3a0c9333 100644 > --- a/mm/memory_hotplug.c > +++ b/mm/memory_hotplug.c > @@ -578,6 +578,9 @@ void __remove_pages(struct zone *zone, unsigned long phys_start_pfn, > __remove_section(zone, __pfn_to_section(pfn), map_offset, > altmap); > map_offset = 0; > + > + if (!(i & 0x0FFF)) > + cond_resched(); We already do have cond_resched before __remove_section. Why is an additional needed? > } > > set_zone_contiguous(zone); > -- > 2.21.0 > -- Michal Hocko SUSE Labs