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=-5.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,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 3029EC433DB for ; Thu, 18 Feb 2021 15:13:23 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id DAEE364EAD for ; Thu, 18 Feb 2021 15:13:22 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229953AbhBRPNI (ORCPT ); Thu, 18 Feb 2021 10:13:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54540 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233033AbhBRM5v (ORCPT ); Thu, 18 Feb 2021 07:57:51 -0500 Received: from casper.infradead.org (casper.infradead.org [IPv6:2001:8b0:10b:1236::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 78587C061788 for ; Thu, 18 Feb 2021 04:56:43 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Transfer-Encoding: Content-Type:MIME-Version:References:Message-ID:Subject:Cc:To:From:Date: Sender:Reply-To:Content-ID:Content-Description; bh=2US+nsacEnNbgxajBHN8gHhIlm17B6eFkEy6wCvISps=; b=C6H5kURGZ35GnV2sfJMKdRIBBr s0806pvqWvxYmulhqLpSCIzCaYys9tg/cselQLoCYAk53i4DB4U4Xi3g9AtbBICOI13m+996lKgZV Onx01Qc56w/MPnO5tzzUKM+mMxGYCpipWlKH3lpmgvrUbNZRkTECMSgmjquWgriJ+XZ4JZCEDc7tP jmjTbdBOtYN4dq3xgvB67VGb7z6LAt370h25rwCtF48cO3eVBxIdVmKh1RadiuARfq5qJ407DGOJU KC4Kzp36w77sxHjYoasmWzHQPwdHSPbK9sLfirxLDIJyhbTKkdcTRDpnLi6T4lPpmh+X3Jjjn69Ax yaDJtCcg==; Received: from j217100.upc-j.chello.nl ([24.132.217.100] helo=noisy.programming.kicks-ass.net) by casper.infradead.org with esmtpsa (Exim 4.94 #2 (Red Hat Linux)) id 1lCipj-001g4k-QU; Thu, 18 Feb 2021 12:55:06 +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 3B3E83003E5; Thu, 18 Feb 2021 13:55:00 +0100 (CET) Received: by hirez.programming.kicks-ass.net (Postfix, from userid 1000) id 2BA81201F184F; Thu, 18 Feb 2021 13:55:00 +0100 (CET) Date: Thu, 18 Feb 2021 13:55:00 +0100 From: Peter Zijlstra To: Nadav Amit Cc: Thomas Gleixner , "linux-kernel@vger.kernel.org" , Andy Lutomirski , Dave Hansen , Rik van Riel , Josh Poimboeuf Subject: Re: [PATCH v5 1/8] smp: Run functions concurrently in smp_call_function_many_cond() Message-ID: References: <20210209221653.614098-1-namit@vmware.com> <20210209221653.614098-2-namit@vmware.com> <457D8FBC-8F64-48E9-B9E2-1A316DB0C2B6@vmware.com> <9093B9DA-D29D-422F-8315-750CFDBF2690@vmware.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: 8bit In-Reply-To: <9093B9DA-D29D-422F-8315-750CFDBF2690@vmware.com> Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Feb 17, 2021 at 01:02:41AM +0000, Nadav Amit wrote: > > On Feb 16, 2021, at 10:59 AM, Peter Zijlstra wrote: > > > > On Tue, Feb 16, 2021 at 06:53:09PM +0000, Nadav Amit wrote: > >>> On Feb 16, 2021, at 8:32 AM, Peter Zijlstra wrote: > > > >>> I'm not sure I can explain it yet. It did get me looking at > >>> on_each_cpu() and it appears that wants to be converted too, something > >>> like the below perhaps. > >> > >> Looks like a good cleanup, but I cannot say I understand the problem and how > >> it would solve it. Err... > > > > Yeah, me neither. Bit of a mystery so far. > > This stall seems to be real. Intuitively I presumed preemption was > mistakenly enabled, but it does not seem so. > > Any chance you can build the kernel with “CONFIG_CSD_LOCK_WAIT_DEBUG=Y” and > rerun it? Perhaps that output will tell us more. Sadly not my system. It's a KernelCI box.