Messages in this thread | | | Date | Sat, 12 Feb 2005 00:56:54 +0100 | From | Matthias-Christian Ott <> | Subject | Re: 2.6-bk: cpu hotplug + preempt = smp_processor_id warnings galore |
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Nathan Lynch wrote:
>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/ > > > Hi! Use get_cpu() (It disables preemption) or __smp_processor_id () (on a smp).
Matthias-Christian Ott - 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/
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