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/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 2a1bef9..47c03f4 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -650,6 +650,50 @@
return err;
}
+static u64 huge_pte_to_pagemap_entry(pte_t pte, int offset)
+{
+ u64 pme = 0;
+ if (pte_present(pte))
+ pme = PM_PFRAME(pte_pfn(pte) + offset)
+ | PM_PSHIFT(PAGE_SHIFT) | PM_PRESENT;
+ return pme;
+}
+
+static int pagemap_hugetlb_range(pte_t *pte, unsigned long addr,
+ unsigned long end, struct mm_walk *walk)
+{
+ struct vm_area_struct *vma;
+ struct pagemapread *pm = walk->private;
+ struct hstate *hs = NULL;
+ int err = 0;
+
+ vma = find_vma(walk->mm, addr);
+ if (vma)
+ hs = hstate_vma(vma);
+ for (; addr != end; addr += PAGE_SIZE) {
+ u64 pfn = PM_NOT_PRESENT;
+
+ if (vma && (addr >= vma->vm_end)) {
+ vma = find_vma(walk->mm, addr);
+ if (vma)
+ hs = hstate_vma(vma);
+ }
+
+ if (vma && (vma->vm_start <= addr) && is_vm_hugetlb_page(vma)) {
+ /* calculate pfn of the "raw" page in the hugepage. */
+ int offset = (addr & ~huge_page_mask(hs)) >> PAGE_SHIFT;
+ pfn = huge_pte_to_pagemap_entry(*pte, offset);
+ }
+ err = add_to_pagemap(addr, pfn, pm);
+ if (err)
+ return err;
+ }
+
+ cond_resched();
+
+ return err;
+}
+
/*
* /proc/pid/pagemap - an array mapping virtual pages to pfns
*
@@ -742,6 +786,7 @@
pagemap_walk.pmd_entry = pagemap_pte_range;
pagemap_walk.pte_hole = pagemap_pte_hole;
+ pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;
pagemap_walk.mm = mm;
pagemap_walk.private = ±