Messages in this thread | | | Subject | Re: Panic when cpu hot-remove | From | fandongdong <> | Date | Thu, 18 Jun 2015 15:54:15 +0800 |
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在 2015/6/18 15:27, fandongdong 写道: > > > 在 2015/6/18 13:40, Jiang Liu 写道: >> On 2015/6/17 22:36, Alex Williamson wrote: >>> On Wed, 2015-06-17 at 13:52 +0200, Joerg Roedeljoro wrote: >>>> On Wed, Jun 17, 2015 at 10:42:49AM +0000, 范冬冬 wrote: >>>>> Hi maintainer, >>>>> >>>>> We found a problem that a panic happen when cpu was hot-removed. >>>>> We also trace the problem according to the calltrace information. >>>>> An endless loop happen because value head is not equal to value >>>>> tail forever in the function qi_check_fault( ). >>>>> The location code is as follows: >>>>> >>>>> >>>>> do { >>>>> if (qi->desc_status[head] == QI_IN_USE) >>>>> qi->desc_status[head] = QI_ABORT; >>>>> head = (head - 2 + QI_LENGTH) % QI_LENGTH; >>>>> } while (head != tail); >>>> Hmm, this code interates only over every second QI descriptor, and >>>> tail >>>> probably points to a descriptor that is not iterated over. >>>> >>>> Jiang, can you please have a look? >>> I think that part is normal, the way we use the queue is to always >>> submit a work operation followed by a wait operation so that we can >>> determine the work operation is complete. That's done via >>> qi_submit_sync(). We have had spurious reports of the queue getting >>> impossibly out of sync though. I saw one that was somehow linked to >>> the >>> I/O AT DMA engine. Roland Dreier saw something similar[1]. I'm not >>> sure if they're related to this, but maybe worth comparing. Thanks, >> Thanks, Alex and Joerg! >> >> Hi Dongdong, >> Could you please help to give some instructions about how to >> reproduce this issue? I will try to reproduce it if possible. >> Thanks! >> Gerry > Hi Gerry, > > We're running kernel 4.1.0 on a 4-socket system and we want to > offline socket 1. > Steps as follows: > > echo 1 > /sys/firmware/acpi/hotplug/force_remove > echo 1 > /sys/devices/LNXSYSTM:00/LNXSYBUS:00/ACPI0004:01/eject > > Thanks! > Dongdong >>> Alex >>> >>> [1] >>> http://lists.linuxfoundation.org/pipermail/iommu/2015-January/011502.html >>> >>> -- >>> 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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