[PATCH 2/2] Report the MMU pagesize in /proc/pid/smaps

From: Mel Gorman
Date: Thu Oct 16 2008 - 11:59:25 EST


The KernelPageSize entry in /proc/pid/smaps is the pagesize used by the
kernel to back a VMA. This matches the size used by the MMU in the majority
of cases. However, one counter-example occurs on PPC64 kernels whereby
a kernel using 64K as a base pagesize may still use 4K pages for the MMU
on older processor. To distinguish, this patch reports MMUPageSize as the
pagesize used by the MMU in /proc/pid/smaps.

Signed-off-by: Mel Gorman <mel@xxxxxxxxx>
---
arch/powerpc/include/asm/hugetlb.h | 6 ++++++
arch/powerpc/mm/hugetlbpage.c | 7 +++++++
fs/proc/task_mmu.c | 6 ++++--
include/linux/hugetlb.h | 3 +++
mm/hugetlb.c | 13 +++++++++++++
5 files changed, 33 insertions(+), 2 deletions(-)

diff --git a/arch/powerpc/include/asm/hugetlb.h b/arch/powerpc/include/asm/hugetlb.h
index 26f0d0a..2655146 100644
--- a/arch/powerpc/include/asm/hugetlb.h
+++ b/arch/powerpc/include/asm/hugetlb.h
@@ -18,6 +18,12 @@ pte_t huge_ptep_get_and_clear(struct mm_struct *mm, unsigned long addr,
pte_t *ptep);

/*
+ * The version of vma_mmu_pagesize() in arch/powerpc/mm/hugetlbpage.c needs
+ * to override the version in mm/hugetlb.c
+ */
+#define vma_mmu_pagesize vma_mmu_pagesize
+
+/*
* If the arch doesn't supply something else, assume that hugepage
* size aligned regions are ok without further preparation.
*/
diff --git a/arch/powerpc/mm/hugetlbpage.c b/arch/powerpc/mm/hugetlbpage.c
index a117024..edc0c69 100644
--- a/arch/powerpc/mm/hugetlbpage.c
+++ b/arch/powerpc/mm/hugetlbpage.c
@@ -510,6 +510,13 @@ unsigned long hugetlb_get_unmapped_area(struct file *file, unsigned long addr,
return slice_get_unmapped_area(addr, len, flags, mmu_psize, 1, 0);
}

+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+ unsigned int psize = get_slice_psize(vma->vm_mm, vma->vm_start);
+
+ return 1UL << mmu_psize_to_shift(psize);
+}
+
/*
* Called by asm hashtable.S for doing lazy icache flush
*/
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 71c9868..3517892 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -392,7 +392,8 @@ static int show_smap(struct seq_file *m, void *v)
"Private_Dirty: %8lu kB\n"
"Referenced: %8lu kB\n"
"Swap: %8lu kB\n"
- "KernelPageSize: %8lu kB\n",
+ "KernelPageSize: %8lu kB\n"
+ "MMUPageSize: %8lu kB\n",
(vma->vm_end - vma->vm_start) >> 10,
mss.resident >> 10,
(unsigned long)(mss.pss >> (10 + PSS_SHIFT)),
@@ -402,7 +403,8 @@ static int show_smap(struct seq_file *m, void *v)
mss.private_dirty >> 10,
mss.referenced >> 10,
mss.swap >> 10,
- vma_kernel_pagesize(vma) >> 10);
+ vma_kernel_pagesize(vma) >> 10,
+ vma_mmu_pagesize(vma) >> 10);

return ret;
}
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index ace04a7..5056021 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -233,6 +233,8 @@ static inline unsigned long huge_page_size(struct hstate *h)

extern unsigned long vma_kernel_pagesize(struct vm_area_struct *vma);

+extern unsigned long vma_mmu_pagesize(struct vm_area_struct *vma);
+
static inline unsigned long huge_page_mask(struct hstate *h)
{
return h->mask;
@@ -274,6 +276,7 @@ struct hstate {};
#define huge_page_size(h) PAGE_SIZE
#define huge_page_mask(h) PAGE_MASK
#define vma_kernel_pagesize(v) PAGE_SIZE
+#define vma_mmu_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)
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 7cb27ec..fee3d1d 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -235,6 +235,19 @@ unsigned long vma_kernel_pagesize(struct vm_area_struct *vma)
}

/*
+ * Return the page size being used by the MMU to back a VMA. In the majority
+ * of cases, the page size used by the kernel matches the MMU size. On
+ * architectures where it differs, an architecture-specific version of this
+ * function is required.
+ */
+#ifndef vma_mmu_pagesize
+unsigned long vma_mmu_pagesize(struct vm_area_struct *vma)
+{
+ return vma_kernel_pagesize(vma);
+}
+#endif
+
+/*
* Flags for MAP_PRIVATE reservations. These are stored in the bottom
* bits of the reservation map pointer, which are always clear due to
* alignment.
--
1.5.6.5

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