lkml.org 
[lkml]   [2012]   [Jul]   [26]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH -alternative] mm: hugetlbfs: Close race during teardown of hugetlbfs shared page tables V2 (resend)
On 07/20/2012 10:36 AM, Michal Hocko wrote:

> --- a/arch/x86/mm/hugetlbpage.c
> +++ b/arch/x86/mm/hugetlbpage.c
> @@ -81,7 +81,12 @@ static void huge_pmd_share(struct mm_struct *mm, unsigned long addr, pud_t *pud)
> if (saddr) {
> spte = huge_pte_offset(svma->vm_mm, saddr);
> if (spte) {
> - get_page(virt_to_page(spte));
> + struct page *spte_page = virt_to_page(spte);
> + if (!is_hugetlb_pmd_page_valid(spte_page)) {

What prevents somebody else from marking the hugetlb
pmd invalid, between here...

> + spte = NULL;
> + continue;
> + }

... and here?

> + get_page(spte_page);
> break;
> }

I think need to take the refcount before checking whether
the hugetlb pmd is still valid.

Also, disregard my previous email in this thread, I just
read Mel's detailed explanation and wrapped my brain
around the bug :)


\
 
 \ /
  Last update: 2012-07-26 21:21    [W:0.166 / U:3.180 seconds]
©2003-2017 Jasper Spaans. hosted at Digital OceanAdvertise on this site