linux-kernel - Re: [PATCH 3/3] flush_tlb_range() needs ->page_table_lock when ->mmap

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Date:	Mon, 5 Mar 2012 12:30:19 -0800
From:	Linus Torvalds <torvalds@...ux-foundation.org>
To:	Al Viro <viro@...iv.linux.org.uk>
Cc:	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 3/3] flush_tlb_range() needs ->page_table_lock when
 ->mmap_sem is not held

Is this safe? And why does it need it? Please add more explanations.

                  Linus

On Sun, Mar 4, 2012 at 10:40 PM, Al Viro <viro@...iv.linux.org.uk> wrote:
>
> Signed-off-by: Al Viro <viro@...iv.linux.org.uk>
> ---
>  mm/hugetlb.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
>
> diff --git a/mm/hugetlb.c b/mm/hugetlb.c
> index 5f34bd8..a876871 100644
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -2277,8 +2277,8 @@ void __unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
>                        set_page_dirty(page);
>                list_add(&page->lru, &page_list);
>        }
> -       spin_unlock(&mm->page_table_lock);
>        flush_tlb_range(vma, start, end);
> +       spin_unlock(&mm->page_table_lock);
>        mmu_notifier_invalidate_range_end(mm, start, end);
>        list_for_each_entry_safe(page, tmp, &page_list, lru) {
>                page_remove_rmap(page);
> --
> 1.7.2.5
>
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