From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752476AbeCMSzw (ORCPT ); Tue, 13 Mar 2018 14:55:52 -0400 Received: from mail.linuxfoundation.org ([140.211.169.12]:60216 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751901AbeCMSzv (ORCPT ); Tue, 13 Mar 2018 14:55:51 -0400 Date: Tue, 13 Mar 2018 11:55:49 -0700 From: Andrew Morton To: Pavel Tatashin Cc: steven.sistare@oracle.com, daniel.m.jordan@oracle.com, m.mizuma@jp.fujitsu.com, mhocko@suse.com, catalin.marinas@arm.com, takahiro.akashi@linaro.org, gi-oh.kim@profitbricks.com, heiko.carstens@de.ibm.com, baiyaowei@cmss.chinamobile.com, richard.weiyang@gmail.com, paul.burton@mips.com, miles.chen@mediatek.com, vbabka@suse.cz, mgorman@suse.de, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [v5 1/2] mm: disable interrupts while initializing deferred pages Message-Id: <20180313115549.7badec1c6b85eb5a1cf21eb6@linux-foundation.org> In-Reply-To: <20180313160430.hbjnyiazadt3jwa6@xakep.localdomain> References: <20180309220807.24961-1-pasha.tatashin@oracle.com> <20180309220807.24961-2-pasha.tatashin@oracle.com> <20180312130410.e2fce8e5e38bc2086c7fd924@linux-foundation.org> <20180313160430.hbjnyiazadt3jwa6@xakep.localdomain> X-Mailer: Sylpheed 3.6.0 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, 13 Mar 2018 12:04:30 -0400 Pavel Tatashin wrote: > > > > > --- a/mm/page_alloc.c > > > +++ b/mm/page_alloc.c > > > @@ -1506,7 +1506,6 @@ static void __init deferred_free_pages(int nid, int zid, unsigned long pfn, > > > } else if (!(pfn & nr_pgmask)) { > > > deferred_free_range(pfn - nr_free, nr_free); > > > nr_free = 1; > > > - cond_resched(); > > > } else { > > > nr_free++; > > > > And how can we simply remove these cond_resched()s? I assume this is > > being done because interrupts are now disabled? But those were there > > for a reason, weren't they? > > We must remove cond_resched() because we can't sleep anymore. They were > added to fight NMI timeouts, so I will replace them with > touch_nmi_watchdog() in a follow-up fix. This makes no sense. Any code section where we can add cond_resched() was never subject to NMI timeouts because that code cannot be running with disabled interrupts.