Hugetlb HPTE hashing weirdness

Benjamin Herrenschmidt benh at
Thu Sep 22 09:27:57 EST 2005

> I may be mistaken, but it looks like for small pages the vsid is used as
> the "key" to the hardware hash table but for huge pages only the virtual
> page frame number (vpn) is used.  Could someone explain the difference
> between the way huge pages and normal pages are hashed?  Using only the
> vpn seems like it would result in false hash hits whenever separate
> programs map huge pages at the same virtual address.

The vsid should be used in both case, it "smells" like we may not be
invalidating pages properly on exit, I'll have a look.

Can you send me the test program ?


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