From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-yw0-x242.google.com (mail-yw0-x242.google.com [IPv6:2607:f8b0:4002:c05::242]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by lists.ozlabs.org (Postfix) with ESMTPS id 3syRCJ0KkjzDvNr for ; Tue, 18 Oct 2016 05:13:16 +1100 (AEDT) Received: by mail-yw0-x242.google.com with SMTP id u124so7138448ywg.1 for ; Mon, 17 Oct 2016 11:13:15 -0700 (PDT) Sender: Tejun Heo Date: Mon, 17 Oct 2016 14:13:12 -0400 From: Tejun Heo To: Michael Ellerman Cc: torvalds@linux-foundation.org, linux-kernel@vger.kernel.org, jiangshanlai@gmail.com, akpm@linux-foundation.org, kernel-team@fb.com, "linuxppc-dev@lists.ozlabs.org" Subject: Re: Oops on Power8 (was Re: [PATCH v2 1/7] workqueue: make workqueue available early during boot) Message-ID: <20161017181312.GA6248@htj.duckdns.org> References: <1473967821-24363-1-git-send-email-tj@kernel.org> <1473967821-24363-2-git-send-email-tj@kernel.org> <20160917172314.GB10771@mtj.duckdns.org> <87twck5wqo.fsf@concordia.ellerman.id.au> <20161010130253.GB29742@mtj.duckdns.org> <87a8eb5dwa.fsf@concordia.ellerman.id.au> <20161014150757.GA11102@mtj.duckdns.org> <87mvi6c59q.fsf@concordia.ellerman.id.au> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii In-Reply-To: <87mvi6c59q.fsf@concordia.ellerman.id.au> List-Id: Linux on PowerPC Developers Mail List List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Hello, On Sat, Oct 15, 2016 at 08:48:01PM +1100, Michael Ellerman wrote: > > Hmm... it doesn't reproduce it here and can't see how the commit would > > affect this given that it doesn't really change when the kworker > > kthreads are being created. > > Try turning on CONFIG_DEBUG_PER_CPU_MAPS=y ? > > That will warn if you're indexing off the end of a cpu mask and just > getting lucky with the result. That's not happening on x86. That could mean that powerpc is initializing cpu_possible_mask after workqueue_init_early(). Looking into it. > ------------[ cut here ]------------ > WARNING: CPU: 0 PID: 1 at ../kernel/sched/core.c:1602 try_to_wake_up+0x3f4/0x5c0 > Modules linked in: > CPU: 0 PID: 1 Comm: swapper/0 Not tainted 4.8.0-compiler_gcc-6.2.0-next-20161014-dirty #116 > task: c000000ff9200000 task.stack: c000001ffc084000 > NIP: c0000000000f1ba4 LR: c0000000000f180c CTR: 0000000000000000 > REGS: c000001ffc0878f0 TRAP: 0700 Not tainted (4.8.0-compiler_gcc-6.2.0-next-20161014-dirty) > MSR: 9000000002029033 CR: 28000422 XER: 00000000 > CFAR: c0000000000f18bc SOFTE: 0 > GPR00: c0000000000f180c c000001ffc087b70 c000000000e83400 0000000000000000 > GPR04: 0000000000000002 0000000000000000 0000000000000000 0000000000000000 > GPR08: c000000000dc3400 0000000000000001 0000000000000002 0000000000000000 > GPR12: 0000000000000000 c00000000fb80000 c00000000000e0c8 0000000000000000 > GPR16: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 > GPR20: 0000000000000000 0000000000000000 0000000000000000 c000000000eb8960 > GPR24: 0000000000000000 c000000000d8ce00 0000000000000000 0000000000000000 > GPR28: c0000007f54050f4 0000000000000000 0000000000000000 c0000007f5404900 > NIP [c0000000000f1ba4] try_to_wake_up+0x3f4/0x5c0 > LR [c0000000000f180c] try_to_wake_up+0x5c/0x5c0 > Call Trace: > [c000001ffc087b70] [c0000000000f180c] try_to_wake_up+0x5c/0x5c0 (unreliable) > [c000001ffc087bf0] [c0000000000d53e4] create_worker+0x144/0x250 > [c000001ffc087c90] [c000000000cf7930] workqueue_init+0x170/0x19c > [c000001ffc087d00] [c000000000ce0e74] kernel_init_freeable+0x158/0x360 > [c000001ffc087dc0] [c00000000000e0e4] kernel_init+0x24/0x160 > [c000001ffc087e30] [c00000000000bfa0] ret_from_kernel_thread+0x5c/0xbc > Instruction dump: > e8790890 4bff6ed9 2fa30000 419e00dc 60000000 4bfffe54 3d02fff4 8928d7f9 > 2f890000 409e0018 39200001 9928d7f9 <0fe00000> 60000000 60420000 3b5f0368 > ---[ end trace 0000000000000000 ]--- > > But I'm not sure that tells us anything new? Yeah, I should have asked to print out information of the target task but it looks like we have enough information now. Thanks. -- tejun