Re: [PATCH 1/3] fs/userfaultfd.c: remove a redundant check on end

From: Wei Yang
Date: Sat Oct 12 2019 - 05:16:33 EST


Ping for comment :-)

On Fri, Sep 13, 2019 at 05:31:08AM +0800, Wei Yang wrote:
>For the ending vma, there is a check to make sure the end is huge page
>aligned.
>
>The *if* check makes sure vm_start < end <= vm_end. While the first half
>is not necessary, because the *for* clause makes sure vm_start < end.
>
>This patch just removes it.
>
>Signed-off-by: Wei Yang <richardw.yang@xxxxxxxxxxxxxxx>
>---
> fs/userfaultfd.c | 3 +--
> 1 file changed, 1 insertion(+), 2 deletions(-)
>
>diff --git a/fs/userfaultfd.c b/fs/userfaultfd.c
>index 653d8f7c453c..9ce09ac619a2 100644
>--- a/fs/userfaultfd.c
>+++ b/fs/userfaultfd.c
>@@ -1402,8 +1402,7 @@ static int userfaultfd_register(struct userfaultfd_ctx *ctx,
> * If this vma contains ending address, and huge pages
> * check alignment.
> */
>- if (is_vm_hugetlb_page(cur) && end <= cur->vm_end &&
>- end > cur->vm_start) {
>+ if (is_vm_hugetlb_page(cur) && end <= cur->vm_end) {
> unsigned long vma_hpagesize = vma_kernel_pagesize(cur);
>
> ret = -EINVAL;
>--
>2.17.1

--
Wei Yang
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