mm hugetlb: add hugepage support to pagemap
This patch enables extraction of the pfn of a hugepage from
/proc/pid/pagemap in an architecture independent manner.
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,
- munmap() and unlink() the file on hugetlbfs
Without my patches
------------------
$ ./leak_pagemap
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000000000000 1 0 __________________________________
0x0000000000000804 1 0 __R________M______________________ referenced,mmap
0x000000000000086c 81 0 __RU_lA____M______________________ referenced,uptodate,lru,active,mmap
0x0000000000005808 5 0 ___U_______Ma_b___________________ uptodate,mmap,anonymous,swapbacked
0x0000000000005868 12 0 ___U_lA____Ma_b___________________ uptodate,lru,active,mmap,anonymous,swapbacked
0x000000000000586c 1 0 __RU_lA____Ma_b___________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked
total 101 0
The output of page-types don't show any hugepage.
With my patches
---------------
$ ./leak_pagemap
flags page-count MB symbolic-flags long-symbolic-flags
0x0000000000000000 1 0 __________________________________
0x0000000000030000 51100 199 ________________TG________________ compound_tail,huge
0x0000000000028018 100 0 ___UD__________H_G________________ uptodate,dirty,compound_head,huge
0x0000000000000804 1 0 __R________M______________________ referenced,mmap
0x000000000000080c 1 0 __RU_______M______________________ referenced,uptodate,mmap
0x000000000000086c 80 0 __RU_lA____M______________________ referenced,uptodate,lru,active,mmap
0x0000000000005808 4 0 ___U_______Ma_b___________________ uptodate,mmap,anonymous,swapbacked
0x0000000000005868 12 0 ___U_lA____Ma_b___________________ uptodate,lru,active,mmap,anonymous,swapbacked
0x000000000000586c 1 0 __RU_lA____Ma_b___________________ referenced,uptodate,lru,active,mmap,anonymous,swapbacked
total 51300 200
The output of page-types shows 51200 pages contributing to hugepages,
containing 100 head pages and 51100 tail pages as expected.
[akpm@linux-foundation.org: build fix]
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>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index a286915..7b47a57 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -120,15 +120,31 @@
do {
next = pgd_addr_end(addr, end);
- /* skip hugetlb vma to avoid hugepage PMD being cleared
- * in pmd_none_or_clear_bad(). */
+ /*
+ * handle hugetlb vma individually because pagetable walk for
+ * the hugetlb page is dependent on the architecture and
+ * we can't handled it in the same manner as non-huge pages.
+ */
vma = find_vma(walk->mm, addr);
+#ifdef CONFIG_HUGETLB_PAGE
if (vma && is_vm_hugetlb_page(vma)) {
+ pte_t *pte;
+ struct hstate *hs;
+
if (vma->vm_end < next)
next = vma->vm_end;
+ hs = hstate_vma(vma);
+ pte = huge_pte_offset(walk->mm,
+ addr & huge_page_mask(hs));
+ if (pte && !huge_pte_none(huge_ptep_get(pte))
+ && walk->hugetlb_entry)
+ err = walk->hugetlb_entry(pte, addr,
+ next, walk);
+ if (err)
+ break;
continue;
}
-
+#endif
if (pgd_none_or_clear_bad(pgd)) {
if (walk->pte_hole)
err = walk->pte_hole(addr, next, walk);
