[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] Xen crashing when killing a domain with no VCPUs allocated
On Fri, 2014-07-18 at 14:27 +0100, Julien Grall wrote: > Hi all, > > I've been played with the function alloc_vcpu on ARM. And I hit one case > where this function can failed. > > During domain creation, the toolstack will call DOMCTL_max_vcpus which may > fail, for instance because alloc_vcpu didn't succeed. In this case, the > toolstack will call DOMCTL_domaindestroy. And I got the below stack trace. > > It can be reproduced on Xen 4.5 (and I also suspect Xen 4.4) by returning > in an error in vcpu_initialize. > > I'm not sure how to correctly fix it. I think a simple check at the head of the function would be ok. Alternatively perhaps in sched_mode_domain, which could either detect this or could detect a domain in pool0 being moved to pool0 and short circuit. [...] > (XEN) [<00226870>] sched_move_domain+0x3cc/0x42c > (XEN) [<0020925c>] domain_kill+0xc8/0x178 This call path surprised me but it is from: commit bac6334b51d9bcfe57ecf4a4cb5288348fcf044a Author: Juergen Gross <juergen.gross@xxxxxxxxxxxxxx> Date: Tue May 20 15:55:42 2014 +0200 move domain to cpupool0 before destroying it Currently when a domain is destroyed it is removed from the domain_list before all of it's resources, including the cpupool membership, are freed. This can lead to a situation where the domain is still member of a cpupool without for_each_domain_in_cpupool() (or even for_each_domain()) being able to find it any more. This in turn can result in rejection of removing the last cpu from a cpupool, because there seems to be still a domain in the cpupool, even if it can't be found by scanning through all domains. This situation can be avoided by moving the domain to be destroyed to cpupool0 first and then remove it from this cpupool BEFORE deleting it from the domain_list. As cpupool0 is always active and a domain without any cpupool membership is implicitly regarded as belonging to cpupool0, this poses no problem. _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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