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mm hugetlb: add hugepage support to pagemap

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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>
This commit is contained in:
Naoya Horiguchi 2009-12-14 18:00:01 -08:00 committed by Linus Torvalds
parent d33b9f45bd
commit 5dc37642cb
3 changed files with 67 additions and 3 deletions
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45
fs/proc/task_mmu.c
View file

@ -650,6 +650,50 @@ static int pagemap_pte_range(pmd_t *pmd, unsigned long addr, unsigned long end,
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 @@ static ssize_t pagemap_read(struct file *file, char __user *buf,
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 = &pm;

3
include/linux/mm.h
View file

@ -770,6 +770,7 @@ unsigned long unmap_vmas(struct mmu_gather **tlb,
* @pmd_entry: if set, called for each non-empty PMD (3rd-level) entry
* @pte_entry: if set, called for each non-empty PTE (4th-level) entry
* @pte_hole: if set, called for each hole at all levels
* @hugetlb_entry: if set, called for each hugetlb entry
*
* (see walk_page_range for more details)
*/
@ -779,6 +780,8 @@ struct mm_walk {
int (*pmd_entry)(pmd_t *, unsigned long, unsigned long, struct mm_walk *);
int (*pte_entry)(pte_t *, unsigned long, unsigned long, struct mm_walk *);
int (*pte_hole)(unsigned long, unsigned long, struct mm_walk *);
int (*hugetlb_entry)(pte_t *, unsigned long, unsigned long,
struct mm_walk *);
struct mm_struct *mm;
void *private;
};

22
mm/pagewalk.c
View file

@ -120,15 +120,31 @@ int walk_page_range(unsigned long addr, unsigned long end,
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);