The patch titled
Subject: mm: smaps should deal with huge zero page exactly same as normal zero page
has been added to the -mm tree. Its filename is
smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page.patch
This patch should soon appear at
http://ozlabs.org/~akpm/mmots/broken-out/smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page.patch
and later at
http://ozlabs.org/~akpm/mmotm/broken-out/smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page.patch
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------------------------------------------------------
From: Fengwei Yin <yfw.kernel@xxxxxxxxx>
Subject: mm: smaps should deal with huge zero page exactly same as normal zero page
We could see following memory info in /proc/xxxx/smaps with THP enabled.
7bea458b3000-7fea458b3000 r--p 00000000 00:13 39989 /dev/zero
Size: 4294967296 kB
Rss: 10612736 kB
Pss: 10612736 kB
Shared_Clean: 0 kB
Shared_Dirty: 0 kB
Private_Clean: 10612736 kB
Private_Dirty: 0 kB
Referenced: 10612736 kB
Anonymous: 0 kB
AnonHugePages: 10612736 kB
Swap: 0 kB
KernelPageSize: 4 kB
MMUPageSize: 4 kB
Locked: 0 kB
VmFlags: rd mr mw me
which is wrong becuase just huge_zero_page/normal_zero_page is used for
/dev/zero. Most of the value should be 0.
This patch detects huge_zero_page (original implementation just detect
normal_zero_page) and avoids to update the wrong value for huge_zero_page.
Signed-off-by: Fengwei Yin <yfw.kernel@xxxxxxxxx>
Reported-by: Fengguang Wu <fengguang.wu@xxxxxxxxx>
Cc: Dave Hansen <dave.hansen@xxxxxxxxx>
Cc: Naoya Horiguchi <n-horiguchi@xxxxxxxxxxxxx>
Cc: "Kirill A. Shutemov" <kirill@xxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
fs/proc/task_mmu.c | 6 ++++--
include/linux/huge_mm.h | 2 ++
mm/huge_memory.c | 5 +++++
mm/memory.c | 4 ++++
4 files changed, 15 insertions(+), 2 deletions(-)
diff -puN fs/proc/task_mmu.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page fs/proc/task_mmu.c
--- a/fs/proc/task_mmu.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page
+++ a/fs/proc/task_mmu.c
@@ -474,8 +474,11 @@ static void smaps_pte_entry(pte_t ptent,
if (!page)
return;
- if (PageAnon(page))
+ if (PageAnon(page)) {
mss->anonymous += ptent_size;
+ if (PageTransHuge(page))
+ mss->anonymous_thp += HPAGE_PMD_SIZE;
+ }
if (page->index != pgoff)
mss->nonlinear += ptent_size;
@@ -511,7 +514,6 @@ static int smaps_pte_range(pmd_t *pmd, u
if (pmd_trans_huge_lock(pmd, vma, &ptl) == 1) {
smaps_pte_entry(*(pte_t *)pmd, addr, HPAGE_PMD_SIZE, walk);
spin_unlock(ptl);
- mss->anonymous_thp += HPAGE_PMD_SIZE;
return 0;
}
diff -puN include/linux/huge_mm.h~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page include/linux/huge_mm.h
--- a/include/linux/huge_mm.h~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page
+++ a/include/linux/huge_mm.h
@@ -34,6 +34,8 @@ extern int change_huge_pmd(struct vm_are
unsigned long addr, pgprot_t newprot,
int prot_numa);
+extern bool is_huge_zero_pfn(unsigned long pfn);
+
enum transparent_hugepage_flag {
TRANSPARENT_HUGEPAGE_FLAG,
TRANSPARENT_HUGEPAGE_REQ_MADV_FLAG,
diff -puN mm/huge_memory.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page mm/huge_memory.c
--- a/mm/huge_memory.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page
+++ a/mm/huge_memory.c
@@ -183,6 +183,11 @@ static inline bool is_huge_zero_pmd(pmd_
return is_huge_zero_page(pmd_page(pmd));
}
+bool is_huge_zero_pfn(unsigned long pfn)
+{
+ return is_huge_zero_page(pfn_to_page(pfn));
+}
+
static struct page *get_huge_zero_page(void)
{
struct page *zero_page;
diff -puN mm/memory.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page mm/memory.c
--- a/mm/memory.c~smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page
+++ a/mm/memory.c
@@ -41,6 +41,7 @@
#include <linux/kernel_stat.h>
#include <linux/mm.h>
#include <linux/hugetlb.h>
+#include <linux/huge_mm.h>
#include <linux/mman.h>
#include <linux/swap.h>
#include <linux/highmem.h>
@@ -787,6 +788,9 @@ check_pfn:
return NULL;
}
+ if (is_huge_zero_pfn(pfn))
+ return NULL;
+
/*
* NOTE! We still have PageReserved() pages in the page tables.
* eg. VDSO mappings can cause them to exist.
_
Patches currently in -mm which might be from yfw.kernel@xxxxxxxxx are
smaps-should-deal-with-huge-zero-page-exactly-same-as-normal-zero-page.patch
--
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