Commit 08fba699 authored by Mel Gorman's avatar Mel Gorman Committed by Linus Torvalds
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mm: report the pagesize backing a VMA in /proc/pid/smaps

It is useful to verify a hugepage-aware application is using the expected
pagesizes for its memory regions. This patch creates an entry called
KernelPageSize in /proc/pid/smaps that is the size of page used by the
kernel to back a VMA. The entry is not called PageSize as it is possible
the MMU uses a different size. This extension should not break any sensible
parser that skips lines containing unrecognised information.

Signed-off-by: default avatarMel Gorman <>
Acked-by: default avatar"KOSAKI Motohiro" <>
Cc: Alexey Dobriyan <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 238c6d54
......@@ -396,7 +396,8 @@ static int show_smap(struct seq_file *m, void *v)
"Private_Clean: %8lu kB\n"
"Private_Dirty: %8lu kB\n"
"Referenced: %8lu kB\n"
"Swap: %8lu kB\n",
"Swap: %8lu kB\n"
"KernelPageSize: %8lu kB\n",
(vma->vm_end - vma->vm_start) >> 10,
mss.resident >> 10,
(unsigned long)(mss.pss >> (10 + PSS_SHIFT)),
......@@ -405,7 +406,8 @@ static int show_smap(struct seq_file *m, void *v)
mss.private_clean >> 10,
mss.private_dirty >> 10,
mss.referenced >> 10,
mss.swap >> 10);
mss.swap >> 10,
vma_kernel_pagesize(vma) >> 10);
if (m->count < m->size) /* vma is copied successfully */
m->version = (vma != get_gate_vma(task)) ? vma->vm_start : 0;
......@@ -233,6 +233,8 @@ static inline unsigned long huge_page_size(struct hstate *h)
return (unsigned long)PAGE_SIZE << h->order;
extern unsigned long vma_kernel_pagesize(struct vm_area_struct *vma);
static inline unsigned long huge_page_mask(struct hstate *h)
return h->mask;
......@@ -273,6 +275,7 @@ struct hstate {};
#define hstate_inode(i) NULL
#define huge_page_size(h) PAGE_SIZE
#define huge_page_mask(h) PAGE_MASK
#define vma_kernel_pagesize(v) PAGE_SIZE
#define huge_page_order(h) 0
#define huge_page_shift(h) PAGE_SHIFT
static inline unsigned int pages_per_huge_page(struct hstate *h)
......@@ -219,6 +219,22 @@ static pgoff_t vma_hugecache_offset(struct hstate *h,
(vma->vm_pgoff >> huge_page_order(h));
* Return the size of the pages allocated when backing a VMA. In the majority
* cases this will be same size as used by the page table entries.
unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
struct hstate *hstate;
if (!is_vm_hugetlb_page(vma))
return PAGE_SIZE;
hstate = hstate_vma(vma);
return 1UL << (hstate->order + PAGE_SHIFT);
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
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