On Tue, 7 Feb 2012, Andrew Morton wrote:
> On Tue, 7 Feb 2012 16:00:46 -0800 (PST)
> Hugh Dickins <hughd@xxxxxxxxxx> wrote:
>
> > +++ linux/mm/huge_memory.c 2012-02-07 15:37:18.581666053 -0800
> > @@ -2083,7 +2083,7 @@ static void collect_mm_slot(struct mm_sl
> > {
> > struct mm_struct *mm = mm_slot->mm;
> >
> > - VM_BUG_ON(!spin_is_locked(&khugepaged_mm_lock));
> > + VM_BUG_ON(NR_CPUS != 1 && !spin_is_locked(&khugepaged_mm_lock));
>
> We do have assert_spin_locked(), but I couldn't see any way of using it
> while observing these laziness constraints ;)
;) I didn't know about assert_spin_locked(). Hmm, fs/dcache.c seems
to be using that successfully. We could forget about the VM_ part of
it and respin the patch with assert_spin_locked(). I don't really
mind either way: but happy to let laziness win the day - I'm back
on an SMP kernel by now anyway.
>
> Should we patch -stable too?
People seem to have survived very well without it so far, I think
it's an unusual config combination, and quickly obvious if anyone
hits it. But I've no objection if you think it deserves -stable.
Hugh
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