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SubjectRe: Linux 2.6.26-rc7
On Mon, Jun 23, 2008 at 1:26 AM, Linus Torvalds
<torvalds@linux-foundation.org> wrote:
> So assuming it's not the XIP fix, you could try this patch instead. It
> replaces the (insane) use of VM_LOCKED with VM_SHARED (which is a lot more
> meaningful for the case of ZERO_PAGE, but strictly speaking probably
> doesn't matter either), and it teaches it about the fact that
> non-anonymous pages can be populated not just with the "->fault" handler,
> but with "->nopfn" too.
>
> I really don't think it's due to this (nobody sane really uses '->nopfn'),
> but if the XIP disabling patch doesn't make a difference, give it a try.

Linus,

This one fixes the problem! So, it's something strange that VMware is
doing, but anyway, glad you fix it!!!

Thanks for the patch.

Jeff.



> (Most of the patch is obviously the fact that I moved the conditionals
> into a helper inline function to make the dang thing more readable). The
> actual change is trivial.
>
> Linus
>
> ---
> mm/memory.c | 12 ++++++++++--
> 1 files changed, 10 insertions(+), 2 deletions(-)
>
> diff --git a/mm/memory.c b/mm/memory.c
> index 9aefaae..8c5675f 100644
> --- a/mm/memory.c
> +++ b/mm/memory.c
> @@ -1045,6 +1045,15 @@ no_page_table:
> return page;
> }
>
> +/* Can we do the FOLL_ANON optimization? */
> +static inline int use_zero_page(struct vm_area_struct *vma)
> +{
> + if (vma->vm_flags & VM_SHARED)
> + return 0;
> + return !vma->vm_ops ||
> + (!vma->vm_ops->fault && !vma->vm_ops->nopfn);
> +}
> +
> int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> unsigned long start, int len, int write, int force,
> struct page **pages, struct vm_area_struct **vmas)
> @@ -1119,8 +1128,7 @@ int get_user_pages(struct task_struct *tsk, struct mm_struct *mm,
> foll_flags = FOLL_TOUCH;
> if (pages)
> foll_flags |= FOLL_GET;
> - if (!write && !(vma->vm_flags & VM_LOCKED) &&
> - (!vma->vm_ops || !vma->vm_ops->fault))
> + if (!write && use_zero_page(vma))
> foll_flags |= FOLL_ANON;
>
> do {
>


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