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 0233BC433EF for ; Fri, 28 Jan 2022 16:18:21 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1349999AbiA1QSU (ORCPT ); Fri, 28 Jan 2022 11:18:20 -0500 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]:30834 "EHLO mx0a-001b2d01.pphosted.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S235638AbiA1QSS (ORCPT ); Fri, 28 Jan 2022 11:18:18 -0500 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20SFofX8030052; Fri, 28 Jan 2022 16:17:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : references : date : in-reply-to : message-id : mime-version : content-type; s=pp1; bh=WIIEnY4LQjNNxPmo8R0V8UME5jMvyPgAX65kRzl76DE=; b=sEpNqsY6iohNXVKa0ENno++Xz7TAgntaSy7RompeOswHByMidzv92b8BM+VSPiDR1xDz RJ3H5z4cfbfgNeIv9lK0ghlCl84ejUfU3u7NiULdzdCiMz7D53tKz9bEFQKYCt9DSezV GoGP1UqUdPipIJ51tro+Te7VsYUWr0wlL75m0GkFYw8mNouM60cd5P6EBctcZx82csYM Z5B9+JFxJY1VS6X5uqPJ2G6cxIZzfJhQuyqzZcVjOr4ik9/s0qwO+IS8gETrUwPt2hja YHWp5lpZOuwxXttWbCZA7dmRbRAHzH/YscyzJzHsjgjoUy4MDeMCsuA6n/DEqGLmcnaR KA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up2b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:42 +0000 Received: from m0098394.ppops.net (m0098394.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 20SFrJSh018510; Fri, 28 Jan 2022 16:17:41 GMT Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up1f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:41 +0000 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 20SGEC6U032075; Fri, 28 Jan 2022 16:17:39 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma03ams.nl.ibm.com with ESMTP id 3dr9ja373e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:39 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 20SGHX7n38011174 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 28 Jan 2022 16:17:33 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A1525AE055; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2D677AE045; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from tuxmaker.linux.ibm.com (unknown [9.152.85.9]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) From: Sven Schnelle To: Mark Rutland Cc: Steven Rostedt , LKML , Ingo Molnar , Andrew Morton , Yinan Liu , Ard Biesheuvel , Kees Cook , Sachin Sant , linuxppc-dev@lists.ozlabs.org, Russell King , linux-arm-kernel@lists.infradead.org, hca@linux.ibm.com, linux-s390@vger.kernel.org, "Paul E. McKenney" Subject: Re: ftrace hangs waiting for rcu References: <20220127114249.03b1b52b@gandalf.local.home> Date: Fri, 28 Jan 2022 17:17:32 +0100 In-Reply-To: (Mark Rutland's message of "Fri, 28 Jan 2022 16:11:57 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: u8O8FusVp6nn3H4y_5Ekm_czzhxm816Q X-Proofpoint-ORIG-GUID: jYcgQy5HdrGbbLk3NI1FNR-A0FeeLH0u X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-28_05,2022-01-28_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=948 lowpriorityscore=0 malwarescore=0 adultscore=0 impostorscore=0 suspectscore=0 spamscore=0 priorityscore=1501 mlxscore=0 clxscore=1015 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201280101 Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Hi Mark, Mark Rutland writes: > On Fri, Jan 28, 2022 at 05:08:48PM +0100, Sven Schnelle wrote: >> We noticed the PR from Paul and are currently testing the fix. So far >> it's looking good. The configuration where we have seen the hang is a >> bit unusual: >> >> - 16 physical CPUs on the kvm host >> - 248 logical CPUs inside kvm > > Aha! 248 is notably *NOT* a power of two, and in this case the shift would be > wrong (ilog2() would give 7, when we need a shift of 8). > > So I suspect you're hitting the same issue as I was. Argh, indeed! I somehow changed 'power of two' to 'odd number' in my head. I guess it's time for the weekend. :-) Thanks! 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 lists.ozlabs.org (lists.ozlabs.org [112.213.38.117]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id F0291C433F5 for ; Fri, 28 Jan 2022 16:18:59 +0000 (UTC) Received: from boromir.ozlabs.org (localhost [IPv6:::1]) by lists.ozlabs.org (Postfix) with ESMTP id 4JljM62mgrz3Wtt for ; Sat, 29 Jan 2022 03:18:58 +1100 (AEDT) Authentication-Results: lists.ozlabs.org; dkim=fail reason="signature verification failed" (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=sEpNqsY6; dkim-atps=neutral Authentication-Results: lists.ozlabs.org; spf=pass (sender SPF authorized) smtp.mailfrom=linux.ibm.com (client-ip=148.163.156.1; helo=mx0a-001b2d01.pphosted.com; envelope-from=svens@linux.ibm.com; receiver=) Authentication-Results: lists.ozlabs.org; dkim=pass (2048-bit key; unprotected) header.d=ibm.com header.i=@ibm.com header.a=rsa-sha256 header.s=pp1 header.b=sEpNqsY6; dkim-atps=neutral Received: from mx0a-001b2d01.pphosted.com (mx0a-001b2d01.pphosted.com [148.163.156.1]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 4JljLK70Y1z2xsc for ; Sat, 29 Jan 2022 03:18:17 +1100 (AEDT) Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20SFofX8030052; Fri, 28 Jan 2022 16:17:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : references : date : in-reply-to : message-id : mime-version : content-type; s=pp1; bh=WIIEnY4LQjNNxPmo8R0V8UME5jMvyPgAX65kRzl76DE=; b=sEpNqsY6iohNXVKa0ENno++Xz7TAgntaSy7RompeOswHByMidzv92b8BM+VSPiDR1xDz RJ3H5z4cfbfgNeIv9lK0ghlCl84ejUfU3u7NiULdzdCiMz7D53tKz9bEFQKYCt9DSezV GoGP1UqUdPipIJ51tro+Te7VsYUWr0wlL75m0GkFYw8mNouM60cd5P6EBctcZx82csYM Z5B9+JFxJY1VS6X5uqPJ2G6cxIZzfJhQuyqzZcVjOr4ik9/s0qwO+IS8gETrUwPt2hja YHWp5lpZOuwxXttWbCZA7dmRbRAHzH/YscyzJzHsjgjoUy4MDeMCsuA6n/DEqGLmcnaR KA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up2b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:42 +0000 Received: from m0098394.ppops.net (m0098394.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 20SFrJSh018510; Fri, 28 Jan 2022 16:17:41 GMT Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up1f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:41 +0000 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 20SGEC6U032075; Fri, 28 Jan 2022 16:17:39 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma03ams.nl.ibm.com with ESMTP id 3dr9ja373e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:39 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 20SGHX7n38011174 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 28 Jan 2022 16:17:33 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A1525AE055; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2D677AE045; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from tuxmaker.linux.ibm.com (unknown [9.152.85.9]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) From: Sven Schnelle To: Mark Rutland Subject: Re: ftrace hangs waiting for rcu References: <20220127114249.03b1b52b@gandalf.local.home> Date: Fri, 28 Jan 2022 17:17:32 +0100 In-Reply-To: (Mark Rutland's message of "Fri, 28 Jan 2022 16:11:57 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-TM-AS-GCONF: 00 X-Proofpoint-GUID: u8O8FusVp6nn3H4y_5Ekm_czzhxm816Q X-Proofpoint-ORIG-GUID: jYcgQy5HdrGbbLk3NI1FNR-A0FeeLH0u X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-28_05,2022-01-28_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=948 lowpriorityscore=0 malwarescore=0 adultscore=0 impostorscore=0 suspectscore=0 spamscore=0 priorityscore=1501 mlxscore=0 clxscore=1015 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201280101 X-BeenThere: linuxppc-dev@lists.ozlabs.org X-Mailman-Version: 2.1.29 Precedence: list List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Cc: linux-s390@vger.kernel.org, Kees Cook , "Paul E. McKenney" , hca@linux.ibm.com, LKML , Steven Rostedt , Ingo Molnar , Sachin Sant , Russell King , Andrew Morton , Yinan Liu , linuxppc-dev@lists.ozlabs.org, Ard Biesheuvel , linux-arm-kernel@lists.infradead.org Errors-To: linuxppc-dev-bounces+linuxppc-dev=archiver.kernel.org@lists.ozlabs.org Sender: "Linuxppc-dev" Hi Mark, Mark Rutland writes: > On Fri, Jan 28, 2022 at 05:08:48PM +0100, Sven Schnelle wrote: >> We noticed the PR from Paul and are currently testing the fix. So far >> it's looking good. The configuration where we have seen the hang is a >> bit unusual: >> >> - 16 physical CPUs on the kvm host >> - 248 logical CPUs inside kvm > > Aha! 248 is notably *NOT* a power of two, and in this case the shift would be > wrong (ilog2() would give 7, when we need a shift of 8). > > So I suspect you're hitting the same issue as I was. Argh, indeed! I somehow changed 'power of two' to 'odd number' in my head. I guess it's time for the weekend. :-) Thanks! 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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id 79854C433F5 for ; Fri, 28 Jan 2022 16:21:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:MIME-Version:Message-ID:In-Reply-To: Date:References:Subject:Cc:To:From:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=saFSjgsrda4wt3I+C1TxOabom+D5kQVx1+u5+fcPV2A=; b=j8id2lDyikpw5I BHHW8/J9czY8TFccM76CktTuX9LnIscURhpatzmb9/qISVwJHMGAAnXYcPtZH9UiAVVMmbw+ABf/q UgJG7+UgVW/qYbJMUOzKd6Ky7AbraCgFOQRbCj8Z1qydDAN6o+MMF9re2Jjh6EPE3y6KmW5Y2PVDZ pBx++bqZf8HNQhXBQGMd8bb3SE1YRbGz6Bdjs7FoGisjpNt3toIynL9O0J52A+vCc+yv1hHARMlum JvAQSdGX3hNiTsaMYsyJ9GFRkU1FbX79lZL8MXeK4ejT+Fizj3EeouhSFET60Jshz2eS3va5B9ooN Zk4b2TvnG7lnpGYAdA+Q==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1nDTyN-002wIA-9o; Fri, 28 Jan 2022 16:19:40 +0000 Received: from mx0a-001b2d01.pphosted.com ([148.163.156.1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1nDTx0-002viw-8D for linux-arm-kernel@lists.infradead.org; Fri, 28 Jan 2022 16:18:15 +0000 Received: from pps.filterd (m0098394.ppops.net [127.0.0.1]) by mx0a-001b2d01.pphosted.com (8.16.1.2/8.16.1.2) with SMTP id 20SFofX8030052; Fri, 28 Jan 2022 16:17:42 GMT DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=ibm.com; h=from : to : cc : subject : references : date : in-reply-to : message-id : mime-version : content-type; s=pp1; bh=WIIEnY4LQjNNxPmo8R0V8UME5jMvyPgAX65kRzl76DE=; b=sEpNqsY6iohNXVKa0ENno++Xz7TAgntaSy7RompeOswHByMidzv92b8BM+VSPiDR1xDz RJ3H5z4cfbfgNeIv9lK0ghlCl84ejUfU3u7NiULdzdCiMz7D53tKz9bEFQKYCt9DSezV GoGP1UqUdPipIJ51tro+Te7VsYUWr0wlL75m0GkFYw8mNouM60cd5P6EBctcZx82csYM Z5B9+JFxJY1VS6X5uqPJ2G6cxIZzfJhQuyqzZcVjOr4ik9/s0qwO+IS8gETrUwPt2hja YHWp5lpZOuwxXttWbCZA7dmRbRAHzH/YscyzJzHsjgjoUy4MDeMCsuA6n/DEqGLmcnaR KA== Received: from pps.reinject (localhost [127.0.0.1]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up2b-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:42 +0000 Received: from m0098394.ppops.net (m0098394.ppops.net [127.0.0.1]) by pps.reinject (8.16.0.43/8.16.0.43) with SMTP id 20SFrJSh018510; Fri, 28 Jan 2022 16:17:41 GMT Received: from ppma03ams.nl.ibm.com (62.31.33a9.ip4.static.sl-reverse.com [169.51.49.98]) by mx0a-001b2d01.pphosted.com with ESMTP id 3dvh61up1f-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:41 +0000 Received: from pps.filterd (ppma03ams.nl.ibm.com [127.0.0.1]) by ppma03ams.nl.ibm.com (8.16.1.2/8.16.1.2) with SMTP id 20SGEC6U032075; Fri, 28 Jan 2022 16:17:39 GMT Received: from b06cxnps4075.portsmouth.uk.ibm.com (d06relay12.portsmouth.uk.ibm.com [9.149.109.197]) by ppma03ams.nl.ibm.com with ESMTP id 3dr9ja373e-1 (version=TLSv1.2 cipher=ECDHE-RSA-AES256-GCM-SHA384 bits=256 verify=NOT); Fri, 28 Jan 2022 16:17:39 +0000 Received: from d06av26.portsmouth.uk.ibm.com (d06av26.portsmouth.uk.ibm.com [9.149.105.62]) by b06cxnps4075.portsmouth.uk.ibm.com (8.14.9/8.14.9/NCO v10.0) with ESMTP id 20SGHX7n38011174 (version=TLSv1/SSLv3 cipher=DHE-RSA-AES256-GCM-SHA384 bits=256 verify=OK); Fri, 28 Jan 2022 16:17:33 GMT Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id A1525AE055; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from d06av26.portsmouth.uk.ibm.com (unknown [127.0.0.1]) by IMSVA (Postfix) with ESMTP id 2D677AE045; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) Received: from tuxmaker.linux.ibm.com (unknown [9.152.85.9]) by d06av26.portsmouth.uk.ibm.com (Postfix) with ESMTPS; Fri, 28 Jan 2022 16:17:33 +0000 (GMT) From: Sven Schnelle To: Mark Rutland Cc: Steven Rostedt , LKML , Ingo Molnar , Andrew Morton , Yinan Liu , Ard Biesheuvel , Kees Cook , Sachin Sant , linuxppc-dev@lists.ozlabs.org, Russell King , linux-arm-kernel@lists.infradead.org, hca@linux.ibm.com, linux-s390@vger.kernel.org, "Paul E. McKenney" Subject: Re: ftrace hangs waiting for rcu References: <20220127114249.03b1b52b@gandalf.local.home> Date: Fri, 28 Jan 2022 17:17:32 +0100 In-Reply-To: (Mark Rutland's message of "Fri, 28 Jan 2022 16:11:57 +0000") Message-ID: User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/28.0.50 (gnu/linux) MIME-Version: 1.0 X-TM-AS-GCONF: 00 X-Proofpoint-GUID: u8O8FusVp6nn3H4y_5Ekm_czzhxm816Q X-Proofpoint-ORIG-GUID: jYcgQy5HdrGbbLk3NI1FNR-A0FeeLH0u X-Proofpoint-Virus-Version: vendor=baseguard engine=ICAP:2.0.205,Aquarius:18.0.816,Hydra:6.0.425,FMLib:17.11.62.513 definitions=2022-01-28_05,2022-01-28_01,2021-12-02_01 X-Proofpoint-Spam-Details: rule=outbound_notspam policy=outbound score=0 mlxlogscore=948 lowpriorityscore=0 malwarescore=0 adultscore=0 impostorscore=0 suspectscore=0 spamscore=0 priorityscore=1501 mlxscore=0 clxscore=1015 phishscore=0 bulkscore=0 classifier=spam adjust=0 reason=mlx scancount=1 engine=8.12.0-2201110000 definitions=main-2201280101 X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220128_081814_344302_2C63EA73 X-CRM114-Status: GOOD ( 20.92 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org Hi Mark, Mark Rutland writes: > On Fri, Jan 28, 2022 at 05:08:48PM +0100, Sven Schnelle wrote: >> We noticed the PR from Paul and are currently testing the fix. So far >> it's looking good. The configuration where we have seen the hang is a >> bit unusual: >> >> - 16 physical CPUs on the kvm host >> - 248 logical CPUs inside kvm > > Aha! 248 is notably *NOT* a power of two, and in this case the shift would be > wrong (ilog2() would give 7, when we need a shift of 8). > > So I suspect you're hitting the same issue as I was. Argh, indeed! I somehow changed 'power of two' to 'odd number' in my head. I guess it's time for the weekend. :-) Thanks! _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel