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=-8.0 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,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 CAF29C4338F for ; Tue, 17 Aug 2021 23:17:52 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id A956661008 for ; Tue, 17 Aug 2021 23:17:52 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S236383AbhHQXSZ (ORCPT ); Tue, 17 Aug 2021 19:18:25 -0400 Received: from us-smtp-delivery-124.mimecast.com ([216.205.24.124]:54702 "EHLO us-smtp-delivery-124.mimecast.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229466AbhHQXSY (ORCPT ); Tue, 17 Aug 2021 19:18:24 -0400 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1629242269; 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: in-reply-to:in-reply-to:references:references; bh=iqLeheCmzUoPSckkbkHc4q/EKrZdzeXZx6eM4WD1qck=; b=BQEHbxvN+OGh51mixhh8+5YWwTz/1Uc0gXfWCrKfXezVq7AnPr6FdQSocGL+XWjnLissR5 SebfyWuvRat2dpYlOnuJL3hN+prqt7wLYaudKx2PDxWZKypLfvbn0LIXzq7ko85N81oQFU RPNHomG1UD4t3LOV2gL/ALs43gg7RUA= 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-265-cxAPWYwxPOWuRvO00cBsHg-1; Tue, 17 Aug 2021 19:17:45 -0400 X-MC-Unique: cxAPWYwxPOWuRvO00cBsHg-1 Received: from smtp.corp.redhat.com (int-mx08.intmail.prod.int.phx2.redhat.com [10.5.11.23]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id CE9D61009600; Tue, 17 Aug 2021 23:17:43 +0000 (UTC) Received: from asgard.redhat.com (unknown [10.36.110.3]) by smtp.corp.redhat.com (Postfix) with ESMTPS id 3057719D9B; Tue, 17 Aug 2021 23:17:37 +0000 (UTC) Date: Wed, 18 Aug 2021 01:17:34 +0200 From: Eugene Syromiatnikov To: Peter Zijlstra Cc: joel@joelfernandes.org, chris.hyser@oracle.com, joshdon@google.com, mingo@kernel.org, vincent.guittot@linaro.org, valentin.schneider@arm.com, mgorman@suse.de, linux-kernel@vger.kernel.org, tglx@linutronix.de, Christian Brauner , ldv@strace.io Subject: Re: [PATCH 18/19] sched: prctl() core-scheduling interface Message-ID: <20210817231734.GA4449@asgard.redhat.com> References: <20210422120459.447350175@infradead.org> <20210422123309.039845339@infradead.org> <20210817151542.GA1665@asgard.redhat.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.23 (2014-03-12) X-Scanned-By: MIMEDefang 2.84 on 10.5.11.23 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Tue, Aug 17, 2021 at 05:52:43PM +0200, Peter Zijlstra wrote: > Urgh... lemme guess, your HP BIOS is funny and reports more possible > CPUs than you actually have resulting in cpu_possible_mask != > cpu_online_mask. Alternatively, you booted with nr_cpus= or something > daft like that. Yep, it seems to be the case: # cat /sys/devices/system/cpu/possible 0-7 # cat /sys/devices/system/cpu/online 0-3 > > That code does for_each_possible_cpus(i) { rq_lock_irq(cpu_rq(i)); }, > which, because of core-sched, needs rq->core set-up, but because these > CPUs have never been online, that's not done and *BOOM*. > > Or something like that.. I'll try and have a look tomorrow, I'm in dire > need of sleep. >