Commit fe1668ae authored by Chen, Kenneth W's avatar Chen, Kenneth W Committed by Linus Torvalds

[PATCH] enforce proper tlb flush in unmap_hugepage_range

Spotted by Hugh that hugetlb page is free'ed back to global pool before
performing any TLB flush in unmap_hugepage_range().  This potentially allow
threads to abuse free-alloc race condition.

The generic tlb gather code is unsuitable to use by hugetlb, I just open
coded a page gathering list and delayed put_page until tlb flush is
performed.

Cc: Hugh Dickins <hugh@veritas.com>
Signed-off-by: default avatarKen Chen <kenneth.w.chen@intel.com>
Acked-by: default avatarWilliam Irwin <wli@holomorphy.com>
Signed-off-by: default avatarAndrew Morton <akpm@osdl.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@osdl.org>
parent e80ee884
......@@ -364,6 +364,8 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
pte_t *ptep;
pte_t pte;
struct page *page;
struct page *tmp;
LIST_HEAD(page_list);
WARN_ON(!is_vm_hugetlb_page(vma));
BUG_ON(start & ~HPAGE_MASK);
......@@ -384,12 +386,16 @@ void unmap_hugepage_range(struct vm_area_struct *vma, unsigned long start,
continue;
page = pte_page(pte);
put_page(page);
list_add(&page->lru, &page_list);
add_mm_counter(mm, file_rss, (int) -(HPAGE_SIZE / PAGE_SIZE));
}
spin_unlock(&mm->page_table_lock);
flush_tlb_range(vma, start, end);
list_for_each_entry_safe(page, tmp, &page_list, lru) {
list_del(&page->lru);
put_page(page);
}
}
static int hugetlb_cow(struct mm_struct *mm, struct vm_area_struct *vma,
......
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