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=-5.9 required=3.0 tests=FREEMAIL_FORGED_FROMDOMAIN, FREEMAIL_FROM,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SPF_PASS,URIBL_BLOCKED,USER_AGENT_NEOMUTT autolearn=ham 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 51E50C67839 for ; Fri, 14 Dec 2018 04:47:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 13D012086D for ; Fri, 14 Dec 2018 04:47:42 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org 13D012086D Authentication-Results: mail.kernel.org; dmarc=fail (p=none dis=none) header.from=orcon.net.nz Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727028AbeLNErk (ORCPT ); Thu, 13 Dec 2018 23:47:40 -0500 Received: from smtp-2.orcon.net.nz ([60.234.4.43]:49979 "EHLO smtp-2.orcon.net.nz" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726437AbeLNErk (ORCPT ); Thu, 13 Dec 2018 23:47:40 -0500 Received: from [121.99.228.40] (port=30436 helo=tower) by smtp-2.orcon.net.nz with esmtpa (Exim 4.86_2) (envelope-from ) id 1gXfNx-0002fq-N2; Fri, 14 Dec 2018 17:47:37 +1300 Date: Fri, 14 Dec 2018 17:47:33 +1300 From: Michael Cree To: Tejun Heo Cc: linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, debian-alpha@lists.debian.org Subject: Re: Generic kernel fails to boot on Alpha bisected to b38d08f3181c Message-ID: <20181214044733.nr43q4wu22ktasvu@tower> Mail-Followup-To: Michael Cree , Tejun Heo , linux-alpha@vger.kernel.org, linux-kernel@vger.kernel.org, debian-alpha@lists.debian.org References: <20181213082612.bi2dcd6uhzp3t6iq@tower> <20181213160724.GU2509588@devbig004.ftw2.facebook.com> MIME-Version: 1.0 Content-Type: multipart/mixed; boundary="jnbswjcdwgcvwuta" Content-Disposition: inline In-Reply-To: <20181213160724.GU2509588@devbig004.ftw2.facebook.com> User-Agent: NeoMutt/20170113 (1.7.2) X-GeoIP: NZ X-Spam_score: -2.9 X-Spam_score_int: -28 X-Spam_bar: -- Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org --jnbswjcdwgcvwuta Content-Type: text/plain; charset=us-ascii Content-Disposition: inline On Thu, Dec 13, 2018 at 08:07:24AM -0800, Tejun Heo wrote: > Hello, Michael. > > On Thu, Dec 13, 2018 at 09:26:12PM +1300, Michael Cree wrote: > > A kernel built for generic UP Alpha had been noted to fail to boot > > for quite some time (since the release of 3.18). The kernel either > > locks up before printing any messages to the console or just falls > > back into the SRM with a HALT instruction again before any messages > > are printed to the console. A work around is to either use a kernel > > built for generic SMP or to build a machine specific kernel as these > > boot correctly. > > > > Because there were other compile errors at the time it proved > > difficult to bisect, but we are continuing to get complaints about > > it as it renders the Debian Alpha installer somewhat useless, so I > > returned to trying to find the problem and managed to bisect it to: > > > > commit b38d08f3181c5025a7ce84646494cc4748492a3b > > Author: Tejun Heo > > Date: Tue Sep 2 14:46:02 2014 -0400 > > > > percpu: restructure locking > > > > Any suggestions as to what might be the problem and a fix? > > So, the only thing I can think of is that it's calling > spin_unlock_irq() while irq handling isn't set up yet. Can you please > try the followings? > > 1. Convert all spin_[un]lock_irq() to > spin_lock_irqsave/unlock_irqrestore(). Yes, that's it. With the attached patch the kernel boots. Cheers Michael. --jnbswjcdwgcvwuta Content-Type: text/x-diff; charset=us-ascii Content-Disposition: attachment; filename="0001-percpu-convert-spin_lock_irq-to-spin_lock_irqsave.patch" >From e08cf3c714184d8fe168fffcd7d15732924deb1e Mon Sep 17 00:00:00 2001 From: Michael Cree Date: Fri, 14 Dec 2018 17:24:31 +1300 Subject: [PATCH] percpu: convert spin_lock_irq to spin_lock_irqsave. Bisection lead to commit b38d08f3181c ("percpu: restructure locking") as being the cause of lockups at initial boot on the kernel built for generic Alpha. On a suggestion by Tejun Heo that: So, the only thing I can think of is that it's calling spin_unlock_irq() while irq handling isn't set up yet. Can you please try the followings? 1. Convert all spin_[un]lock_irq() to spin_lock_irqsave/unlock_irqrestore(). --- mm/percpu-km.c | 5 +++-- 1 file changed, 3 insertions(+), 2 deletions(-) diff --git a/mm/percpu-km.c b/mm/percpu-km.c index 38de70ab1a0d..0f643dc2dc65 100644 --- a/mm/percpu-km.c +++ b/mm/percpu-km.c @@ -50,6 +50,7 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp) const int nr_pages = pcpu_group_sizes[0] >> PAGE_SHIFT; struct pcpu_chunk *chunk; struct page *pages; + unsigned long flags; int i; chunk = pcpu_alloc_chunk(gfp); @@ -68,9 +69,9 @@ static struct pcpu_chunk *pcpu_create_chunk(gfp_t gfp) chunk->data = pages; chunk->base_addr = page_address(pages) - pcpu_group_offsets[0]; - spin_lock_irq(&pcpu_lock); + spin_lock_irqsave(&pcpu_lock, flags); pcpu_chunk_populated(chunk, 0, nr_pages, false); - spin_unlock_irq(&pcpu_lock); + spin_unlock_irqrestore(&pcpu_lock, flags); pcpu_stats_chunk_alloc(); trace_percpu_create_chunk(chunk->base_addr); -- 2.11.0 --jnbswjcdwgcvwuta--