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=-4.1 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED autolearn=no 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 5245CC56201 for ; Mon, 26 Oct 2020 13:50:19 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 0794321D42 for ; Mon, 26 Oct 2020 13:50:19 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1603720219; bh=YnVWvpRo6BaIhYkS8M3dkSZlTyZ4bE297aSRP3EE2yc=; h=Date:From:To:Cc:Subject:References:In-Reply-To:List-ID:From; b=b6AZw1gpnKBum3TM3th33oLoR/pG5LRc+cYM7YE1eAh/CSnIi3j8MmT+6gJ0ePkeZ VVovXzOXJHvVprW2UsT5uzpqXEGOYO1TAaV17js5785FbSuXCwfRZljzaRB9/F2pI8 VJAwQrEiWtZfPBsFXcHnEmXg8sAAws9ZmBGmg108= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1780685AbgJZNuS (ORCPT ); Mon, 26 Oct 2020 09:50:18 -0400 Received: from mail-qt1-f193.google.com ([209.85.160.193]:33233 "EHLO mail-qt1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S2404378AbgJZNuQ (ORCPT ); Mon, 26 Oct 2020 09:50:16 -0400 Received: by mail-qt1-f193.google.com with SMTP id j62so6691398qtd.0 for ; Mon, 26 Oct 2020 06:50:15 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=sender:date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to; bh=TxfXjOwfBykntP1Jpf/tQTb6j5RyS9vTmp3y0ZTz9iY=; b=hj2Xzb1lS89qCPlK7eJpZN6WVDn7yEvhz2twlUFqiehOWCaTaej0//mbn2FMaBLWIn F8DmpTbIeRFOrtl/Okvy7RHEq7WiFTwBo+PePbx+LWTp2YCj4xddlYVuscGpZ3IJ+oG5 b3UES6VFcG9UeaEmeEa9bqNb87n5yviccl9+PDzNl894xBrHxr5ZNPj92FHGAHIAN8TY ooyxG4RgS33cDTqkBXOv0bc2i+LsBV1CkYSOwgTxt0QD7bG3eqnfluHeFkPQfBDRrIBs gRLxte4i3wvSPNT3sKqXiR5eJ+1OqAy2afreeXeTYcDBDdHkf0qFclAlhIc3y/aZheQ/ 65TA== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:sender:date:from:to:cc:subject:message-id :references:mime-version:content-disposition:in-reply-to; bh=TxfXjOwfBykntP1Jpf/tQTb6j5RyS9vTmp3y0ZTz9iY=; b=iJI8sNtDWNnFl/UhxLhrVZlDLd7fEnDLoGDxV4OY/Hl+c5VBGpkdG/iLXdN0qbjQRa RTfOSEvHe0TXmF5iYI27KiDr8b4SpTuiI/U2Kb9iuYO6QWAwSMIRyPnopdUeZadafpBy PR/PA9rg9w1vqwb9jgjxD++Ud6IB0GJx4rtX5PwDKq8JqNfdLOENUIVP3GtrELqwniJi 2h94da/nBz3H6uFjngzP8UYXJrb39k9m9G1CsicV/g5xTkeFLhQejo1PlwuLBs5wVZgn MIldqHE2roygieN7EQ/xh710oxPSt0EdU1NVzc4PYkhlMB+pqqBNfN3ObCz+0xiKR3ZA jzlw== X-Gm-Message-State: AOAM532KpkkfcxQQ3ID4tcFgJIlla71CbAc7sES/TgYIdhQzgh4gNdrc TLETncapBukAMDv0u6r58ZzWxuI0g128+w== X-Google-Smtp-Source: ABdhPJxOEtJ6n3AC1FOzURdLuieNu+2Vq5bFekGeLN4FlTYCZJELfdfRy36ovzb2dYtDTXJBwu97mQ== X-Received: by 2002:aed:31e3:: with SMTP id 90mr1350645qth.300.1603720215250; Mon, 26 Oct 2020 06:50:15 -0700 (PDT) Received: from localhost (dhcp-48-d6-d5-c6-42-27.cpe.echoes.net. [199.96.181.106]) by smtp.gmail.com with ESMTPSA id b191sm6651842qkg.81.2020.10.26.06.50.14 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Mon, 26 Oct 2020 06:50:14 -0700 (PDT) Sender: Tejun Heo Date: Mon, 26 Oct 2020 09:50:11 -0400 From: Tejun Heo To: qiang.zhang@windriver.com Cc: pmladek@suse.com, akpm@linux-foundation.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org Subject: Re: [PATCH] kthread_worker: re-set CPU affinities if CPU come online Message-ID: <20201026135011.GC73258@mtj.duckdns.org> References: <20201026065213.30477-1-qiang.zhang@windriver.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20201026065213.30477-1-qiang.zhang@windriver.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Mon, Oct 26, 2020 at 02:52:13PM +0800, qiang.zhang@windriver.com wrote: > @@ -737,8 +741,11 @@ __kthread_create_worker(int cpu, unsigned int flags, > if (IS_ERR(task)) > goto fail_task; > > - if (cpu >= 0) > + if (cpu >= 0) { > kthread_bind(task, cpu); > + worker->bind_cpu = cpu; > + cpuhp_state_add_instance_nocalls(kworker_online, &worker->cpuhp_node); > + } > > worker->flags = flags; > worker->task = task; ... > +static int kworker_cpu_online(unsigned int cpu, struct hlist_node *node) > +{ > + struct kthread_worker *worker = hlist_entry(node, struct kthread_worker, cpuhp_node); > + struct task_struct *task = worker->task; > + > + if (cpu == worker->bind_cpu) > + WARN_ON_ONCE(set_cpus_allowed_ptr(task, cpumask_of(cpu)) < 0); > + return 0; > +} I don't think this works. The kthread may have changed its binding while running using set_cpus_allowed_ptr() as you're doing above. Besides, when a cpu goes offline, the bound kthread can fall back to other cpus but its cpu mask isn't cleared, is it? Thanks. -- tejun