Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262348AbVBKX32 (ORCPT ); Fri, 11 Feb 2005 18:29:28 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262289AbVBKX32 (ORCPT ); Fri, 11 Feb 2005 18:29:28 -0500 Received: from orb.pobox.com ([207.8.226.5]:10134 "EHLO orb.pobox.com") by vger.kernel.org with ESMTP id S262348AbVBKX20 (ORCPT ); Fri, 11 Feb 2005 18:28:26 -0500 Date: Fri, 11 Feb 2005 17:28:21 -0600 From: Nathan Lynch To: lkml Cc: Rusty Russell , Ingo Molnar Subject: 2.6-bk: cpu hotplug + preempt = smp_processor_id warnings galore Message-ID: <20050211232821.GA14499@otto> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline User-Agent: Mutt/1.5.6+20040907i Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2631 Lines: 67 Hi- With 2.6.11-rc3-bk7 on ppc64 I am seeing lots of smp_processor_id warnings whenever I hotplug cpus: # echo 0 > /sys/devices/system/cpu/cpu1/online cpu 1 (hwid 1) Ready to die... BUG: using smp_processor_id() in preemptible [00000001] code: ksoftirqd/1/5 caller is .ksoftirqd+0xbc/0x1f8 Call Trace: [c0000000fffbbce0] [ffffffffffffffff] 0xffffffffffffffff (unreliable) [c0000000fffbbd60] [c0000000001c9f1c] .smp_processor_id+0x154/0x168 [c0000000fffbbe20] [c00000000005f414] .ksoftirqd+0xbc/0x1f8 [c0000000fffbbed0] [c0000000000764cc] .kthread+0x128/0x134 [c0000000fffbbf90] [c000000000014248] .kernel_thread+0x4c/0x6c I believe the above warning is caused by the local_softirq_pending call on a "foreign" cpu before ksoftirqd/1 has been stopped. Looking at the code, I think this doesn't indicate a real bug, but it would be better if ksoftirqd didn't check local_softirq_pending after it's been kicked off its cpu, right? # echo 1 > /sys/devices/system/cpu/cpu1/online BUG: using smp_processor_id() in preemptible [00000001] code: swapper/0 caller is .dedicated_idle+0x68/0x22c Call Trace: [c0000000fffafc50] [ffffffffffffffff] 0xffffffffffffffff (unreliable) [c0000000fffafcd0] [c0000000001c9f1c] .smp_processor_id+0x154/0x168 [c0000000fffafd90] [c00000000000f998] .dedicated_idle+0x68/0x22c [c0000000fffafe80] [c00000000000fce8] .cpu_idle+0x34/0x4c [c0000000fffaff00] [c00000000003a744] .start_secondary+0x10c/0x150 [c0000000fffaff90] [c00000000000bd28] .enable_64b_mode+0x0/0x28 Should ppc64 simply use _smp_processor_id() in its idle loop code (like i386)? If I online and offline cpus rapidly enough I can eventually get the following: printk: 49 messages suppressed. BUG: using smp_processor_id() in preemptible [00000001] code: events/3/1262 caller is .cache_reap+0x21c/0x2b8 Call Trace: [c0000000ed67bb90] [ffffffffffffffff] 0xffffffffffffffff (unreliable) [c0000000ed67bc10] [c0000000001c9f1c] .smp_processor_id+0x154/0x168 [c0000000ed67bcd0] [c0000000000938e8] .cache_reap+0x21c/0x2b8 [c0000000ed67bda0] [c00000000006f4bc] .worker_thread+0x230/0x310 [c0000000ed67bed0] [c0000000000764cc] .kthread+0x128/0x134 [c0000000ed67bf90] [c000000000014248] .kernel_thread+0x4c/0x6c And this will repeat over and over even after I stop hotplugging cpus... from the same events thread so I think it's somehow gotten "stuck"? Anything I can do to further debug? Nathan - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/