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=-16.2 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER,INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS 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 D1E9CC11F67 for ; Thu, 1 Jul 2021 21:08:16 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id B280F613C7 for ; Thu, 1 Jul 2021 21:08:16 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234441AbhGAVJK (ORCPT ); Thu, 1 Jul 2021 17:09:10 -0400 Received: from us-smtp-delivery-124.mimecast.com ([170.10.133.124]:56390 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S234122AbhGAVI4 (ORCPT ); Thu, 1 Jul 2021 17:08:56 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1625173584; 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: references:references; bh=PLewHXDmPjFB924jxgbIi8PWfwqgckw1/ZnpEwhMiSQ=; b=HwQlxK+/ndboTWBsEC4w9yNbOhnE7jeVaw/21WeQnU7iaoky9BhQfLBPmdT6W/FnT/NE8e pAqdgwaFrXdEOVXnw2RReNecgEHh4UKc9GTWMiBis7EU5lLRiheAruQ6jNiSahGvBjmHxi bdoy/riMH0A62hrttbT9TI8apwbsRYM= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-68-zgHly7bGOOydyYagHFzIRw-1; Thu, 01 Jul 2021 17:06:23 -0400 X-MC-Unique: zgHly7bGOOydyYagHFzIRw-1 Received: from smtp.corp.redhat.com (int-mx06.intmail.prod.int.phx2.redhat.com [10.5.11.16]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 87BFC1084F4C; Thu, 1 Jul 2021 21:06:22 +0000 (UTC) Received: from fuller.cnet (ovpn-112-6.gru2.redhat.com [10.97.112.6]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 33DE65C230; Thu, 1 Jul 2021 21:06:22 +0000 (UTC) Received: by fuller.cnet (Postfix, from userid 1000) id 332A74179DC7; Thu, 1 Jul 2021 18:06:06 -0300 (-03) Message-ID: <20210701210458.413105321@fuller.cnet> User-Agent: quilt/0.66 Date: Thu, 01 Jul 2021 18:03:41 -0300 From: Marcelo Tosatti To: linux-kernel@vger.kernel.org Cc: Christoph Lameter , Thomas Gleixner , Frederic Weisbecker , Juri Lelli , Nitesh Lal , Marcelo Tosatti Subject: [patch 5/5] mm: vmstat_refresh: avoid queueing work item if cpu stats are clean References: <20210701210336.358118649@fuller.cnet> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 X-Scanned-By: MIMEDefang 2.79 on 10.5.11.16 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org It is not necessary to queue work item to run refresh_vm_stats on a remote CPU if that CPU has no dirty stats and no per-CPU allocations for remote nodes. This fixes sosreport hang (which uses vmstat_refresh) with spinning SCHED_FIFO process. Signed-off-by: Marcelo Tosatti Index: linux-2.6-vmstat-update/mm/vmstat.c =================================================================== --- linux-2.6-vmstat-update.orig/mm/vmstat.c +++ linux-2.6-vmstat-update/mm/vmstat.c @@ -1895,17 +1895,39 @@ static bool need_update(int cpu) } #ifdef CONFIG_PROC_FS -static void refresh_vm_stats(struct work_struct *work) +static bool need_drain_remote_zones(int cpu) +{ + struct zone *zone; + + for_each_populated_zone(zone) { + struct per_cpu_pageset *p; + + p = per_cpu_ptr(zone->pageset, cpu); + + if (!p->pcp.count) + continue; + if (!p->expire) + continue; + if (zone_to_nid(zone) == cpu_to_node(cpu)) + continue; + + return true; + } + + return false; +} + +static long refresh_vm_stats(void *arg) { refresh_cpu_vm_stats(true); + return 0; } int vmstat_refresh(struct ctl_table *table, int write, void *buffer, size_t *lenp, loff_t *ppos) { long val; - int err; - int i; + int i, cpu; /* * The regular update, every sysctl_stat_interval, may come later @@ -1919,9 +1941,15 @@ int vmstat_refresh(struct ctl_table *tab * transiently negative values, report an error here if any of * the stats is negative, so we know to go looking for imbalance. */ - err = schedule_on_each_cpu(refresh_vm_stats); - if (err) - return err; + get_online_cpus(); + for_each_online_cpu(cpu) { + if (need_update(cpu) || need_drain_remote_zones(cpu)) + work_on_cpu(cpu, refresh_vm_stats, NULL); + + cond_resched(); + } + put_online_cpus(); + for (i = 0; i < NR_VM_ZONE_STAT_ITEMS; i++) { /* * Skip checking stats known to go negative occasionally.