Linda Walsh writes:
> Richard Gooch wrote:
> >
> > Linda Walsh writes:
> > > > Removing overcommit might make malloc() return null, but that's only one
> > > > of a host of ways to allocate memory. The other methods don't have a
> > > > return value. So arguing that "overcommit is bad, because it breaks the
> > > > malloc() return value" is pointless.
> > >
> > > What other methods? calloc - ENOMEM, open <object>, ENOMEM, fork:
> > > ENOMEM. Etc. All what you would expect if there was NOMEM.
> >
> > Stack "allocation". No error code available.
> >
> Except via "SIGSTKFLT" (16) - Sig Stack Fault if 'caught' --
> likely resulting in a suspend of the process? Is state saved on
> kernel or on user stack? Seems like it couldn't be on the user
> stack, otherwise, how could you deliver it?
My man page says "Stack fault on coprocessor". Hm. What co-processor?
Oh! My 387! At the least, exactly what SIGSTKFLT is delivered for
should be properly and clearly documented.
State is first saved on the kernel stack. If you want to catch a
signal, you need space in the user-space stack. Boom!
So, in low-memory situations, a growing stack can only result in a
signal that either suspends or kills the process. I don't call that
"deterministic" either. You may as well be buggered by the OOM killer.
Regards,
Richard....
Permanent: rgooch@atnf.csiro.au
Current: rgooch@ras.ucalgary.ca
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