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 Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 53502C4332F for ; Wed, 14 Dec 2022 13:34:07 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S238335AbiLNNdl (ORCPT ); Wed, 14 Dec 2022 08:33:41 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:49646 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S238413AbiLNNdJ (ORCPT ); Wed, 14 Dec 2022 08:33:09 -0500 Received: from ams.source.kernel.org (ams.source.kernel.org [145.40.68.75]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 2A49F25294 for ; Wed, 14 Dec 2022 05:33:08 -0800 (PST) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by ams.source.kernel.org (Postfix) with ESMTPS id D4465B818BF for ; Wed, 14 Dec 2022 13:33:06 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 29F6FC43332; Wed, 14 Dec 2022 13:33:04 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=k20201202; t=1671024785; bh=pgq56pmJqqIVUdDDmdTZvjimbzCmSvIS6vFQXH1iDe0=; h=Date:From:To:Cc:Subject:References:In-Reply-To:From; b=hp95v2iTs3ZfzAJUGHlUUIR5CoSDV1/wazuzI3W1ThIJDliqJJ57EiBpic2y4Pl8H 7u15iFp4GHluRmVk3LCOFGGLVvTvGVRMriKwtjhoZJ7spggCDrZxtk+xGnrxHG+xTq JLY2FPLl7x36mbOOYSIRdw4v8kU+O2ZIc9Z+Wgx18QF/Dl7iWGlk+swxrOnTuQ2q5O JhgNoU4ABB6g8uS1RrQYOkexXo4PJnHykNfyB+f7xGY2fW/QGUfQqG1LJmpnWQcQma rA8pu/Ek8vYx5bGVeQzUkxWQicQ3aj57oxvsqPZ6nwKXWyEk/Hrgzu/QGCXuMj3V4r wrPHmjrmNGXMQ== Date: Wed, 14 Dec 2022 14:33:02 +0100 From: Frederic Weisbecker To: Marcelo Tosatti Cc: atomlin@redhat.com, cl@linux.com, tglx@linutronix.de, mingo@kernel.org, peterz@infradead.org, pauld@redhat.com, neelx@redhat.com, oleksandr@natalenko.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH v9 3/5] mm/vmstat: manage per-CPU stats from CPU context when NOHZ full Message-ID: <20221214133302.GA1931356@lothringen> References: <20221206161826.698593151@redhat.com> <20221206162416.474800121@redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20221206162416.474800121@redhat.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Dec 06, 2022 at 01:18:29PM -0300, Marcelo Tosatti wrote: > static inline void vmstat_mark_dirty(void) > { > + int cpu = smp_processor_id(); > + > + if (tick_nohz_full_cpu(cpu) && !this_cpu_read(vmstat_dirty)) { > + struct delayed_work *dw; > + > + dw = &per_cpu(vmstat_work, cpu); > + if (!delayed_work_pending(dw)) { > + unsigned long delay; > + > + delay = round_jiffies_relative(sysctl_stat_interval); > + queue_delayed_work_on(cpu, mm_percpu_wq, dw, delay); Currently the vmstat_work is flushed on cpu_hotplug (CPUHP_AP_ONLINE_DYN). vmstat_shepherd makes sure to not rearm it afterward. But now it looks possible for the above to do that mistake? > + } > + } > this_cpu_write(vmstat_dirty, true); > } > @@ -2009,6 +2028,10 @@ static void vmstat_shepherd(struct work_ > for_each_online_cpu(cpu) { > struct delayed_work *dw = &per_cpu(vmstat_work, cpu); > > + /* NOHZ full CPUs manage their own vmstat flushing */ > + if (tick_nohz_full_cpu(smp_processor_id())) It should be the remote CPU instead of the current one. Thanks. > + continue; > + > if (!delayed_work_pending(dw) && per_cpu(vmstat_dirty, cpu)) > queue_delayed_work_on(cpu, mm_percpu_wq, dw, 0); >