| To: | Mukesh <mukesh.rathor@xxxxxxxxxx>, <xen-devel@xxxxxxxxxxxxxxxxxxx> |
|---|---|
| Subject: | Re: [Xen-devel] Re: A race condition introduced by changeset 15175: Re-init hypercall stubs page after HVM save/restore |
| From: | Keir Fraser <keir.fraser@xxxxxxxxxxxxx> |
| Date: | 2008年10月21日 08:05:50 +0100 |
| Cc: | "Cui, Dexuan" <dexuan.cui@xxxxxxxxx> |
| Delivery-date: | 2008年10月21日 00:06:19 -0700 |
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| Thread-topic: | [Xen-devel] Re: A race condition introduced by changeset 15175: Re-init hypercall stubs page after HVM save/restore |
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On 21/10/08 04:38, "Mukesh" <mukesh.rathor@xxxxxxxxxx> wrote: >> Hi Dexuan, >> >> Are you really sure that this is the problem? The suspend_lock was >> introduced specifically to solve this problem. Note that the BSP takes this >> lock before messing with the hypercall page. >> >> -- Keir > > I'm also looking at this now (I'm on 3.1.4 BTW). I see both hang and panic. it > appears I see the hang because the "master" vcpu is trying to catch other > vcpus > right at the cpu_relax so it can grab the lock in write mode. With many VCPUs > it's just not happening..... Not sure i like the design of this very much... > i'm > gonna try to modify it a bit .... Hmmm, yes, agreed. We need a completely different approach, or a lock which doesn't allow in more readers when there is a waiting writer. I'll look into it. -- Keir _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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