From 7bf07f3d4b4358aa6d99a26d7a0165f1e91c3fcc Mon Sep 17 00:00:00 2001 From: Adam Litke Date: Sat, 3 Sep 2005 15:55:00 -0700 Subject: [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 Cc: Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- mm/hugetlb.c | 2 -- 1 file changed, 2 deletions(-) (limited to 'mm') diff --git a/mm/hugetlb.c b/mm/hugetlb.c index 6bf720bc662c..901ac523a1c3 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)); -- cgit v1.2.3