[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] [PATCH 2/4] x86/PoD: Identify when a domain has already been killed from PoD exhaustion
On 02/11/15 14:07, George Dunlap wrote: > On 30/10/15 18:33, Andrew Cooper wrote: >> p2m_pod_demand_populate() can be entered repeatedly during a single path >> through the hypervisor, e.g. on a toolstack batch map operation. >> >> The domain might be crashed, but the interface currently lacks a way of >> passing an error back through the generic p2m layer. >> >> Longterm the p2m layer needs reworking to allow errors to be returned, but in >> the short term, avoid repeatedly re-sweeping the domain after it has already >> been crashed from PoD exhaustion. >> >> Signed-off-by: Andrew Cooper <andrew.cooper3@xxxxxxxxxx> >> --- >> CC: Jan Beulich <JBeulich@xxxxxxxx> >> CC: George Dunlap <george.dunlap@xxxxxxxxxxxxx> >> --- >> xen/arch/x86/mm/p2m-pod.c | 3 ++- >> xen/include/asm-x86/p2m.h | 2 ++ >> 2 files changed, 4 insertions(+), 1 deletion(-) >> >> diff --git a/xen/arch/x86/mm/p2m-pod.c b/xen/arch/x86/mm/p2m-pod.c >> index be15cf3..6fb054f 100644 >> --- a/xen/arch/x86/mm/p2m-pod.c >> +++ b/xen/arch/x86/mm/p2m-pod.c >> @@ -1048,7 +1048,7 @@ p2m_pod_demand_populate(struct p2m_domain *p2m, >> unsigned long gfn, >> /* This check is done with the pod lock held. This will make sure that >> * even if d->is_dying changes under our feet, p2m_pod_empty_cache() >> * won't start until we're done. */ >> - if ( unlikely(d->is_dying) ) >> + if ( unlikely(d->is_dying) || p2m->pod.dead ) > So after getting lost in a maze of twisty passages, it looks like > "d->is_dying" might be the wrong thing to check here. d->is_dying is > *only* set, AFAICT, in two places: > - in domain_kill(), which is only called for XEN_DOMCTL_destroydomain > - in domain_create(), if the creation failed for some reason. d->is_dying indicates that the domains resources are starting to be torn down. It is the correct check here. > > Would it make more sense to check d->is_shutting_down instead? A domain resume hypercall can clear d->is_shutting_down, making it an inappropriate check. > > Having some sort of pod-specific flag seems like the wrong solution. All of this patch is the wrong solution, but is necessary until the generic p2m interface can properly represent errors. ~Andrew _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxx http://lists.xen.org/xen-devel
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