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    [PATCH] mm: update split ptlock Kconfig · 7b6ac9df
    Hugh Dickins 提交于
    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: NHugh Dickins <hugh@veritas.com>
    Signed-off-by: NAndrew Morton <akpm@osdl.org>
    Signed-off-by: NLinus Torvalds <torvalds@osdl.org>
    7b6ac9df
Kconfig 4.3 KB