diff options
| author | Adam Litke <agl@us.ibm.com> | 2005-09-03 15:55:00 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@evo.osdl.org> | 2005-09-05 00:05:46 -0700 |
| commit | 7bf07f3d4b4358aa6d99a26d7a0165f1e91c3fcc (patch) | |
| tree | 150e1f1172e3a7912b37bef7b06a657d47bc1657 | |
| parent | 32e51a8c976fc72c3e9bcece9767d9908816bf8e (diff) | |
[PATCH] hugetlb: move stale pte check into huge_pte_alloc()
Initial Post (Wed, 17 Aug 2005)
This patch moves the
if (! pte_none(*pte))
hugetlb_clean_stale_pgtable(pte);
logic into huge_pte_alloc() so all of its callers can be immune to the bug
described by Kenneth Chen at http://lkml.org/lkml/2004/6/16/246
> It turns out there is a bug in hugetlb_prefault(): with 3 level page table,
> huge_pte_alloc() might return a pmd that points to a PTE page. It happens
> if the virtual address for hugetlb mmap is recycled from previously used
> normal page mmap. free_pgtables() might not scrub the pmd entry on
> munmap and hugetlb_prefault skips on any pmd presence regardless what type
> it is.
Unless I am missing something, it seems more correct to place the check inside
huge_pte_alloc() to prevent a the same bug wherever a huge pte is allocated.
It also allows checking for this condition when lazily faulting huge pages
later in the series.
Signed-off-by: Adam Litke <agl@us.ibm.com>
Cc: <linux-mm@kvack.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
| -rw-r--r-- | arch/i386/mm/hugetlbpage.c | 13 | ||||
| -rw-r--r-- | mm/hugetlb.c | 2 |
2 files changed, 11 insertions, 4 deletions
diff --git a/arch/i386/mm/hugetlbpage.c b/arch/i386/mm/hugetlbpage.c index 3b099f32b94..57c486f0e89 100644 --- a/arch/i386/mm/hugetlbpage.c +++ b/arch/i386/mm/hugetlbpage.c @@ -22,12 +22,21 @@ pte_t *huge_pte_alloc(struct mm_struct *mm, unsigned long addr) { pgd_t *pgd; pud_t *pud; - pmd_t *pmd = NULL; + pmd_t *pmd; + pte_t *pte = NULL; pgd = pgd_offset(mm, addr); pud = pud_alloc(mm, pgd, addr); pmd = pmd_alloc(mm, pud, addr); - return (pte_t *) pmd; + + if (!pmd) + goto out; + + pte = (pte_t *) pmd; + if (!pte_none(*pte) && !pte_huge(*pte)) + hugetlb_clean_stale_pgtable(pte); +out: + return pte; } pte_t *huge_pte_offset(struct mm_struct *mm, unsigned long addr) diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6bf720bc662..901ac523a1c 100644 --- a/mm/hugetlb.c +++ b/mm/hugetlb.c @@ -360,8 +360,6 @@ int hugetlb_prefault(struct address_space *mapping, struct vm_area_struct *vma) ret = -ENOMEM; goto out; } - if (! pte_none(*pte)) - hugetlb_clean_stale_pgtable(pte); idx = ((addr - vma->vm_start) >> HPAGE_SHIFT) + (vma->vm_pgoff >> (HPAGE_SHIFT - PAGE_SHIFT)); |