lkml.org 
[lkml]   [2012]   [Aug]   [3]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [patch] hugetlb: correct page offset index for sharing pmd
On Fri 03-08-12 20:56:45, Hillf Danton wrote:
> The computation of page offset index is open coded, and incorrect, to
> be used in scanning prio tree, as huge page offset is required, and is
> fixed with the well defined routine.

I guess that nobody reported this because if someone really wants to
share he will use aligned address for mmap/shmat and so the index is 0.
Anyway it is worth fixing. Thanks for pointing out!

>
> Signed-off-by: Hillf Danton <dhillf@gmail.com>
> ---
>
> --- a/arch/x86/mm/hugetlbpage.c Fri Aug 3 20:34:58 2012
> +++ b/arch/x86/mm/hugetlbpage.c Fri Aug 3 20:40:16 2012
> @@ -72,12 +72,15 @@ static void huge_pmd_share(struct mm_str
> if (!vma_shareable(vma, addr))
> return;
>
> + idx = linear_page_index(vma, addr);
> +

You can use linear_hugepage_index directly and remove the idx
initialization as well.

> mutex_lock(&mapping->i_mmap_mutex);
> vma_prio_tree_foreach(svma, &iter, &mapping->i_mmap, idx, idx) {
> if (svma == vma)
> continue;
>
> - saddr = page_table_shareable(svma, vma, addr, idx);
> + saddr = page_table_shareable(svma, vma, addr,
> + idx * (PMD_SIZE/PAGE_SIZE));

Why not just fixing page_table_shareable as well rather than playing
tricks like this?

> if (saddr) {
> spte = huge_pte_offset(svma->vm_mm, saddr);
> if (spte) {
> --

--
Michal Hocko
SUSE Labs


\
 
 \ /
  Last update: 2012-08-03 16:21    [W:0.101 / U:0.716 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site