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authorNaoya Horiguchi <n-horiguchi@ah.jp.nec.com>2009-12-14 17:59:59 -0800
committerLinus Torvalds <torvalds@linux-foundation.org>2009-12-15 08:53:24 -0800
commitd33b9f45bd24a6391bc05e2b5a13c1b5787ca9c2 (patch)
treec79c7a452a18f513efbbc807440812432778332f /mm/pagewalk.c
parent4f16fc107d9c9b8a72aa19b189a9216e90a7aaef (diff)
downloadlinux-d33b9f45bd24a6391bc05e2b5a13c1b5787ca9c2.tar.gz
mm: hugetlb: fix hugepage memory leak in walk_page_range()
Most callers of pmd_none_or_clear_bad() check whether the target page is in a hugepage or not, but walk_page_range() do not check it. So if we read /proc/pid/pagemap for the hugepage on x86 machine, the hugepage memory is leaked as shown below. This patch fixes it. Details ======= My test program (leak_pagemap) works as follows: - creat() and mmap() a file on hugetlbfs (file size is 200MB == 100 hugepages,) - read()/write() something on it, - call page-types with option -p (walk around the page tables), - munmap() and unlink() the file on hugetlbfs Without my patches ------------------ $ cat /proc/meminfo |grep "HugePage" HugePages_Total: 1000 HugePages_Free: 1000 HugePages_Rsvd: 0 HugePages_Surp: 0 $ ./leak_pagemap [snip output] $ cat /proc/meminfo |grep "HugePage" HugePages_Total: 1000 HugePages_Free: 900 HugePages_Rsvd: 0 HugePages_Surp: 0 $ ls /hugetlbfs/ $ 100 hugepages are accounted as used while there is no file on hugetlbfs. With my patches --------------- $ cat /proc/meminfo |grep "HugePage" HugePages_Total: 1000 HugePages_Free: 1000 HugePages_Rsvd: 0 HugePages_Surp: 0 $ ./leak_pagemap [snip output] $ cat /proc/meminfo |grep "HugePage" HugePages_Total: 1000 HugePages_Free: 1000 HugePages_Rsvd: 0 HugePages_Surp: 0 $ ls /hugetlbfs $ No memory leaks. Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com> Cc: Andi Kleen <ak@linux.intel.com> Cc: Wu Fengguang <fengguang.wu@intel.com> Cc: Hugh Dickins <hugh.dickins@tiscali.co.uk> Cc: Mel Gorman <mel@csn.ul.ie> Cc: Lee Schermerhorn <lee.schermerhorn@hp.com> Cc: Andy Whitcroft <apw@canonical.com> Cc: David Rientjes <rientjes@google.com> Cc: <stable@kernel.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm/pagewalk.c')
-rw-r--r--mm/pagewalk.c16
1 files changed, 15 insertions, 1 deletions
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d5878bed784..a286915e23e 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -1,6 +1,7 @@
#include <linux/mm.h>
#include <linux/highmem.h>
#include <linux/sched.h>
+#include <linux/hugetlb.h>
static int walk_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
struct mm_walk *walk)
@@ -107,6 +108,7 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd_t *pgd;
unsigned long next;
int err = 0;
+ struct vm_area_struct *vma;
if (addr >= end)
return err;
@@ -117,11 +119,22 @@ int walk_page_range(unsigned long addr, unsigned long end,
pgd = pgd_offset(walk->mm, addr);
do {
next = pgd_addr_end(addr, end);
+
+ /* skip hugetlb vma to avoid hugepage PMD being cleared
+ * in pmd_none_or_clear_bad(). */
+ vma = find_vma(walk->mm, addr);
+ if (vma && is_vm_hugetlb_page(vma)) {
+ if (vma->vm_end < next)
+ next = vma->vm_end;
+ continue;
+ }
+
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
if (err)
break;
+ pgd++;
continue;
}
if (walk->pgd_entry)
@@ -131,7 +144,8 @@ int walk_page_range(unsigned long addr, unsigned long end,
err = walk_pud_range(pgd, addr, next, walk);
if (err)
break;
- } while (pgd++, addr = next, addr != end);
+ pgd++;
+ } while (addr = next, addr != end);
return err;
}