From fe1668ae5bf0145014c71797febd9ad5670d5d05 Mon Sep 17 00:00:00 2001
From: "Chen, Kenneth W" <kenneth.w.chen@intel.com>
Date: Wed, 4 Oct 2006 02:15:24 -0700
Subject: [PATCH] [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: Ken Chen <kenneth.w.chen@intel.com>
Acked-by: William Irwin <wli@holomorphy.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
---
mm/hugetlb.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7c7d03dbf73dc..1d709ff528e1e 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -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,