Messages in this thread | | | From | Catalin Marinas <> | Date | Wed, 19 Sep 2012 10:12:28 +0100 | Subject | Re: [PATCH 2/3] mm: thp: Fix the update_mmu_cache() last argument passing in mm/huge_memory.c |
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On 18 September 2012 20:33, Andrew Morton <akpm@linux-foundation.org> wrote: > On Sat, 15 Sep 2012 15:38:33 +0200 > Ralf Baechle <ralf@linux-mips.org> wrote: >> On Tue, Sep 11, 2012 at 05:47:15PM +0100, Will Deacon wrote: >> > The update_mmu_cache() takes a pointer (to pte_t by default) as the last >> > argument but the huge_memory.c passes a pmd_t value. The patch changes >> > the argument to the pmd_t * pointer. >> > >> > Signed-off-by: Catalin Marinas <catalin.marinas@arm.com> >> > Signed-off-by: Steve Capper <steve.capper@arm.com> >> > Signed-off-by: Will Deacon <will.deacon@arm.com> >> > --- >> > mm/huge_memory.c | 6 +++--- >> > 1 files changed, 3 insertions(+), 3 deletions(-) >> > >> > diff --git a/mm/huge_memory.c b/mm/huge_memory.c >> > index 57c4b93..4aa6d02 100644 >> > --- a/mm/huge_memory.c >> > +++ b/mm/huge_memory.c >> > @@ -934,7 +934,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma, >> > entry = pmd_mkyoung(orig_pmd); >> > entry = maybe_pmd_mkwrite(pmd_mkdirty(entry), vma); >> > if (pmdp_set_access_flags(vma, haddr, pmd, entry, 1)) >> > - update_mmu_cache(vma, address, entry); >> > + update_mmu_cache(vma, address, pmd); >> >> Documentation/cachetlb.txt will need an update as well. Currently it says: >> >> 5) void update_mmu_cache(struct vm_area_struct *vma, >> unsigned long address, pte_t *ptep) > > Yes please.
Should we just use a generic (void *) for the last argument or force a cast in mm/huge_memory.c?
Ralf's point is that transparent huge page code calls update_mmu_cache with a (pmd_t *) as the last argument. This could make sense for THP as it assumes that huge pages can only be created at the pmd level. But that's unlike mm/hugetlb.c which casts huge page types to pte_t, even though on ARM they are implemented at the pmd level.
On ARM (with VIPT caches) update_mmu_cache() is empty like on x86, though a static inline rather than macro.
-- Catalin
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