Re: [PATCH 2/3] mm: thp: Fix the update_mmu_cache() last argumentpassing in mm/huge_memory.c

From: Michal Hocko
Date: Wed Sep 12 2012 - 11:40:34 EST


On Tue 11-09-12 17:47:15, Will Deacon wrote:
> From: Catalin Marinas <catalin.marinas@xxxxxxx>
>
> 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@xxxxxxx>
> Signed-off-by: Steve Capper <steve.capper@xxxxxxx>
> Signed-off-by: Will Deacon <will.deacon@xxxxxxx>
> ---
> 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);

I am not sure but shouldn't we use the new entry rather than the given
pmd?

> ret |= VM_FAULT_WRITE;
> goto out_unlock;
> }
> @@ -986,7 +986,7 @@ int do_huge_pmd_wp_page(struct mm_struct *mm, struct vm_area_struct *vma,
> pmdp_clear_flush_notify(vma, haddr, pmd);
> page_add_new_anon_rmap(new_page, vma, haddr);
> set_pmd_at(mm, haddr, pmd, entry);
> - update_mmu_cache(vma, address, entry);
> + update_mmu_cache(vma, address, pmd);
> page_remove_rmap(page);
> put_page(page);
> ret |= VM_FAULT_WRITE;
> @@ -1989,7 +1989,7 @@ static void collapse_huge_page(struct mm_struct *mm,
> BUG_ON(!pmd_none(*pmd));
> page_add_new_anon_rmap(new_page, vma, address);
> set_pmd_at(mm, address, pmd, _pmd);
> - update_mmu_cache(vma, address, _pmd);
> + update_mmu_cache(vma, address, pmd);
> prepare_pmd_huge_pte(pgtable, mm);
> spin_unlock(&mm->page_table_lock);
>
> --
> 1.7.4.1
>

--
Michal Hocko
SUSE Labs
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