On Fri, May 03, 2013 at 06:19:03PM +1000, Benjamin Herrenschmidt wrote: > On Fri, 2013-05-03 at 14:52 +1000, David Gibson wrote: > > Here, specifically, the fact that PAGE_BUSY is in PAGE_THP_HPTEFLAGS > > is likely to be bad. If the page is busy, it's in the middle of > > update so can't stably be considered the same as anything. > > _PAGE_BUSY is more like a read lock. It means it's being hashed, so what > is not stable is _PAGE_HASHPTE, slot index, _ACCESSED and _DIRTY. The > rest is stable and usually is what pmd_same looks at (though I have a > small doubt vs. _ACCESSED and _DIRTY but at least x86 doesn't care since > they are updated by HW).
Ok. It still seems very odd to me that _PAGE_BUSY would be in the THP
version of _PAGE_HASHPTE, but not the normal one.
--
David Gibson | I'll have my music baroque, and my code
david AT gibson.dropbear.id.au | minimalist, thank you. NOT _the_ _other_
| _way_ _around_!
http://www.ozlabs.org/~dgibson
signature.asc
Description: Digital signature
_______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
