* Re: + mm-hugetlb-fix-hugepage-memory-leak-in-walk_page_range.patch added to -mm tree
[not found] <200912082239.nB8MdgwG019623@imap1.linux-foundation.org>
@ 2009-12-09 1:58 ` Naoya Horiguchi
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From: Naoya Horiguchi @ 2009-12-09 1:58 UTC (permalink / raw)
To: akpm
Cc: mm-commits, ak, apw, fengguang.wu, hugh.dickins,
lee.schermerhorn, mel, rientjes, stable, LKML, linux-mm
> Subject: mm: hugetlb: fix hugepage memory leak in walk_page_range()
> From: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
>
> Most callers of pmd_none_or_clear_bad() check whether the target page is
> in a hugepage or not, but mincore() and walk_page_range() do not check it.
> So if we use mincore() on a hugepage on x86 machine, the hugepage memory
> is leaked as shown below. This patch fixes it by extending mincore()
> system call to support hugepages.
>
> Details
> =======
> My test program (leak_mincore) works as follows:
> - creat() and mmap() a file on hugetlbfs (file size is 200MB == 100 hugepages,)
> - read()/write() something on it,
> - call mincore() for first ten pages and printf() the values of *vec
> - munmap() and unlink() the file on hugetlbfs
Sorry, this description is for "fix mincore() patch."
Here is "fix walk_page_range() patch."
(I changed some code since previous post and this patch contains them.)
Thanks,
Naoya Horiguchi
-----------
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.
Changelog v2:
- NULL check of vma
- remove redundant ternary operation
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>
---
mm/pagewalk.c | 16 +++++++++++++++-
1 files changed, 15 insertions(+), 1 deletions(-)
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index d5878be..a286915 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;
}
-- 1.6.0.6
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[not found] <200912082239.nB8MdgwG019623@imap1.linux-foundation.org>
2009-12-09 1:58 ` + mm-hugetlb-fix-hugepage-memory-leak-in-walk_page_range.patch added to -mm tree Naoya Horiguchi
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