[Date Prev][Date Next][Thread Prev][Thread Next][Date Index][Thread Index] Re: [Xen-devel] memguard_guard_stack()
>>> Keir Fraser <Keir.Fraser@xxxxxxxxxxxx> 01.05.06 16:09 >>> > >On 1 May 2006, at 12:36, Jan Beulich wrote: > >> Hmm, but I found this precisely because we saw a double fault due to a >> stack overflow. Admittedly this was in the >> context of one of these IPI storms during shotdown that were fixed >> previously, but even that shouldn't result in a stack >> overflow, should it ? Jan > >How many CPUs were in the system? That code path was rather dodgy: the >function forcibly enabled interrupts and so a single CPU could nest in >that function up to (NR_CPUS-1) times which, if you had say 32 CPUs in >the system could certainly cause problems. I don't think it's >indicative of a wider problem in Xen -- for most interrupts (ones bound >to a guest) we don't even reenable interrupt delivery while handling >them, so nested ISRs in Xen are impossible. At least 16 (both stack traces we got were on CPU 15. >I would like to understand exactly what happened in the context of your >IPI storm (it *is* the machine restart bug we're talking about, right?) Yes. >-- if you had much fewer than 32 CPUs then I need to check exactly how >much stack an invocation of machine_restart() uses. A single nesting level consumed, according to the stack dump, up to 352 bytes. Jan _______________________________________________ Xen-devel mailing list Xen-devel@xxxxxxxxxxxxxxxxxxx http://lists.xensource.com/xen-devel
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