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 53204C433F5 for ; Tue, 21 Dec 2021 17:44:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S240486AbhLURoM (ORCPT ); Tue, 21 Dec 2021 12:44:12 -0500 Received: from out01.mta.xmission.com ([166.70.13.231]:46370 "EHLO out01.mta.xmission.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232502AbhLURoL (ORCPT ); Tue, 21 Dec 2021 12:44:11 -0500 Received: from in01.mta.xmission.com ([166.70.13.51]:42078) by out01.mta.xmission.com with esmtps (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mzjBK-003rMf-7T; Tue, 21 Dec 2021 10:44:10 -0700 Received: from ip68-227-161-49.om.om.cox.net ([68.227.161.49]:54442 helo=email.froward.int.ebiederm.org.xmission.com) by in01.mta.xmission.com with esmtpsa (TLS1.3) tls TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384 (Exim 4.93) (envelope-from ) id 1mzjBI-00HXW0-Sq; Tue, 21 Dec 2021 10:44:09 -0700 From: ebiederm@xmission.com (Eric W. Biederman) To: Stephen Rothwell Cc: Linux Kernel Mailing List , Linux Next Mailing List References: <20211221231611.785b74cf@canb.auug.org.au> Date: Tue, 21 Dec 2021 11:44:02 -0600 In-Reply-To: <20211221231611.785b74cf@canb.auug.org.au> (Stephen Rothwell's message of "Tue, 21 Dec 2021 23:16:11 +1100") Message-ID: <875yrh7t0d.fsf@email.froward.int.ebiederm.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/26.1 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain X-XM-SPF: eid=1mzjBI-00HXW0-Sq;;;mid=<875yrh7t0d.fsf@email.froward.int.ebiederm.org>;;;hst=in01.mta.xmission.com;;;ip=68.227.161.49;;;frm=ebiederm@xmission.com;;;spf=neutral X-XM-AID: U2FsdGVkX1/oYvphKpbGitcm8wW+4EsRngH9CcAlGDY= X-SA-Exim-Connect-IP: 68.227.161.49 X-SA-Exim-Mail-From: ebiederm@xmission.com Subject: Re: linux-next: run time warning after merge of the userns tree X-SA-Exim-Version: 4.2.1 (built Sat, 08 Feb 2020 21:53:50 +0000) X-SA-Exim-Scanned: Yes (on in01.mta.xmission.com) Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Stephen Rothwell writes: > Hi all, > > [I am just guessing at the userns tree.] It is. This is a real brown paper bag bug. Somehow I got the sense of the test wrong and did not notice the warning in my own testing. The fix is just: diff --git a/kernel/sched/core.c b/kernel/sched/core.c index 0404a8c572a1..ee222b89c692 100644 --- a/kernel/sched/core.c +++ b/kernel/sched/core.c @@ -9425,7 +9425,7 @@ void __init sched_init(void) * if we want to avoid special-casing it in code that deals with per-CPU * kthreads. */ - WARN_ON(set_kthread_struct(current)); + WARN_ON(!set_kthread_struct(current)); /* * Make us the idle thread. Technically, schedule() should not be I will get that fixed in my for-next branch shortly. > > My qemu boot test of a powerpc pseries_le_defconfig kernel produced > this warning: > > SLUB: HWalign=128, Order=0-3, MinObjects=0, CPUs=1, Nodes=1 > ftrace: allocating 33453 entries in 13 pages > ftrace: allocated 13 pages with 3 groups > trace event string verifier disabled > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 0 at kernel/sched/core.c:9469 sched_init+0x45c/0x4f4 > Modules linked in: > CPU: 0 PID: 0 Comm: swapper Not tainted 5.16.0-rc6 #2 > NIP: c000000002027c98 LR: c000000002027c94 CTR: 0000000000000000 > REGS: c00000000278bb80 TRAP: 0700 Not tainted (5.16.0-rc6) > MSR: 8000000002021033 CR: 84000220 XER: 00000000 > CFAR: c00000000016c1fc IRQMASK: 1 > GPR00: c000000002027c94 c00000000278be20 c00000000278d300 0000000000000001 > GPR04: c000000000f88788 c000000002865d98 c000000007070680 0000000000000001 > GPR08: 000000007dae0000 c000000007070630 0000000000000000 0000000000000001 > GPR12: 0000000000000000 c000000002970000 0000000000000000 0000000000000000 > GPR16: 0000000002bf00d0 c0000000027c1f38 c00000000017e510 c000000002867f00 > GPR20: c0000000025306b8 c00000000017b520 c00000000017b200 c0000000028682b8 > GPR24: 0000000000000400 0000000000000000 c0000000027c2470 c0000000027b3a00 > GPR28: c0000000021af900 0000000000000800 0000000000000000 c00000007fc8f900 > NIP [c000000002027c98] sched_init+0x45c/0x4f4 > LR [c000000002027c94] sched_init+0x458/0x4f4 > Call Trace: > [c00000000278be20] [c000000002027c94] sched_init+0x458/0x4f4 (unreliable) > [c00000000278bed0] [c000000002004200] start_kernel+0x53c/0x8cc > [c00000000278bf90] [c00000000000d39c] start_here_common+0x1c/0x600 > Instruction dump: > 90ea0188 f92a0180 3d22fffb 39291890 39490050 7d005028 31080001 7d00512d > 40c2fff4 e86d0908 4a144499 60000000 <0b030000> a08d0008 e86d0908 4bfff849 > ---[ end trace 0000000000000000 ]--- > > Exposed by commit > > 40966e316f86 ("kthread: Ensure struct kthread is present for all kthreads")