tree 1e30fde299519eb964899be79560599e04a32a66
parent c101e77301877086e6f977fcfb140d1cbbe23fd5
author Hugh Dickins <hugh@veritas.com> 1132781857 -0800
committer Linus Torvalds <torvalds@g5.osdl.org> 1132790918 -0800

[PATCH] mm: update split ptlock Kconfig

Closer attention to the arithmetic shows that neither ppc64 nor sparc really
uses one page for multiple page tables: how on earth could they, while
pte_alloc_one returns just a struct page pointer, with no offset?

Well, arm26 manages it by returning a pte_t pointer cast to a struct page
pointer, harumph, then compensating in its pmd_populate.  But arm26 is never
SMP, so it's not a problem for split ptlock either.

And the PA-RISC situation has been recently improved: CONFIG_PA20 works
without the 16-byte alignment which inflated its spinlock_t.  But the current
union of spinlock_t with private does make the 7xxx struct page significantly
larger, even without debug, so disable its split ptlock.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>