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=-2.0 required=3.0 tests=DKIM_INVALID,DKIM_SIGNED, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_SANE_1 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 65995C432C0 for ; Mon, 2 Dec 2019 12:41:13 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 3792C206F0 for ; Mon, 2 Dec 2019 12:41:13 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="signature verification failed" (2048-bit key) header.d=infradead.org header.i=@infradead.org header.b="RgVYKa+F" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727459AbfLBMlL (ORCPT ); Mon, 2 Dec 2019 07:41:11 -0500 Received: from merlin.infradead.org ([205.233.59.134]:44038 "EHLO merlin.infradead.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727354AbfLBMlL (ORCPT ); Mon, 2 Dec 2019 07:41:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=merlin.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description:Resent-Date: Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID:List-Id: List-Help:List-Unsubscribe:List-Subscribe:List-Post:List-Owner:List-Archive; bh=QQVFiLaKtWz8/87xlWuZWGTM6aKj6MiwHzOhtOqM+Kg=; b=RgVYKa+Fv+UL9Bo3kZWCRmezD v6ob10/58yNO8kTMUqM+WP7DSOCvOqBZQsLxiWqpzNzBHMzN0lhCupEACXAQQ2CXo+SXxWkt+Ow11 1MIotONSRD5h97ojPAijNKyfySu6Nm4BGwZgtnkmsMQ0kY+Rp8QDe6Un1R5mzdX2HRsAczi/2p/0J LCT5q2EmdKnifoFUqmzOi7LZ/MLJE8j2qgwEJGpijXMWZygM4+eYKDPm9DJjbbZUTtdquTZNpj5RE Vk9FSkCsyGnaANQ9s26JL2gLat4hMBavpRLUr1OEwEoT7AbtENC3NWy3aba0glXt3AMzkLVQPgrlx 6sS40t0AQ==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by merlin.infradead.org with esmtpsa (Exim 4.92.3 #3 (Red Hat Linux)) id 1ibl0c-0007qf-38; Mon, 02 Dec 2019 12:40:58 +0000 Received: from hirez.programming.kicks-ass.net (hirez.programming.kicks-ass.net [192.168.1.225]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (Client did not present a certificate) by noisy.programming.kicks-ass.net (Postfix) with ESMTPS id 8EEA3301A6C; Mon, 2 Dec 2019 13:39:39 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 6AEB220236A49; Mon, 2 Dec 2019 13:40:55 +0100 (CET) Date: Mon, 2 Dec 2019 13:40:55 +0100 From: Peter Zijlstra To: kan.liang@linux.intel.com Cc: mingo@redhat.com, acme@kernel.org, tglx@linutronix.de, bp@alien8.de, linux-kernel@vger.kernel.org, eranian@google.com, alexey.budankov@linux.intel.com, vitaly.slobodskoy@intel.com, ak@linux.intel.com Subject: Re: [RFC PATCH 3/8] perf: Init/fini PMU specific data Message-ID: <20191202124055.GC2827@hirez.programming.kicks-ass.net> References: <1574954071-6321-1-git-send-email-kan.liang@linux.intel.com> <1574954071-6321-3-git-send-email-kan.liang@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <1574954071-6321-3-git-send-email-kan.liang@linux.intel.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 Thu, Nov 28, 2019 at 07:14:26AM -0800, kan.liang@linux.intel.com wrote: > +static int > +init_system_wide_ctx_data(size_t ctx_size) > +{ > + struct task_struct *g, *p; > + int failed_alloc = 0; > + unsigned long flags; > + > + /* > + * Allocate perf_ctx_data for all existing threads by the first event. > + * > + * The perf_ctx_data for new thread will be allocated in > + * perf_event_fork(). The perf_event_fork() is called after the thread > + * is added into the tasklist. It guarantees that any new threads will > + * not be missed. > + */ > + raw_spin_lock_irqsave(&task_data_events_lock, flags); > + if (atomic_inc_return(&nr_task_data_events) > 1) > + goto unlock; > + > + read_lock(&tasklist_lock); > + > + for_each_process_thread(g, p) { > + /* > + * The PMU specific data may already be allocated by > + * per-process event. Need to update refcounter. > + * init_task_ctx_data_rcu() is called here. > + * Do a quick allocation in first round with GFP_ATOMIC. > + */ > + if (init_task_ctx_data_rcu(p, ctx_size, GFP_ATOMIC)) > + failed_alloc++; > + } This is atricous crap. Also it is completely broken for -RT.