* Michel Lespinasse <wal...@google.com> wrote: > On Fri, Nov 1, 2013 at 1:43 AM, Peter Zijlstra <pet...@infradead.org> wrote: > > > AFAICT this isn't correct at all. We used to protect the vma > > interval tree with the root lock, now we don't. All we've got > > left is the mmap_sem, but anon_vma chains can cross > > address-spaces and thus we're up some creek without no paddle. > > Yes, that was my first thought as well (though I wanted to double > check at first). > > I also want to point out that lately we've seen several changes > sent out that relax locking with no accompanying explanation of > why the relaxed locking would be safe. Please don't do that - > having a lot of performance data is worthless if you can't explain > why the new locking is safe. And I'm not asking to prove a > negative ('lack of any possible races') there, but at least in > this case one could dig out why the root anon vma locking was > introduced and if they think that this reason doesn't apply > anymore, explain why...
By the looks of it it seems to be an unintentional bug, not an intended feature. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majord...@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/