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Subject[RFC V2] mm:change smaps/pagemap_read calculation behavior
This patch change smaps/pagemap_read pagetable walk behavior, to make
sure not skip VM_PFNMAP pagetables,
so that we can calculate COW pages of VM_PFNMAP as normal pages.

Signed-off-by: Yalin Wang <yalin.wang@sonymobile.com>
---
fs/proc/task_mmu.c | 2 ++
include/linux/mm.h | 2 ++
mm/pagewalk.c | 5 +++++
3 files changed, 9 insertions(+)

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index c7267e9..e7d7c43 100644
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -616,6 +616,7 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
struct mem_size_stats mss;
struct mm_walk smaps_walk = {
.pmd_entry = smaps_pte_range,
+ .test_walk = generic_walk_page_test_no_skip,
.mm = vma->vm_mm,
.private = &mss,
};
@@ -1264,6 +1265,7 @@ 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.test_walk = generic_walk_page_test_no_skip;
#ifdef CONFIG_HUGETLB_PAGE
pagemap_walk.hugetlb_entry = pagemap_hugetlb_range;
#endif
diff --git a/include/linux/mm.h b/include/linux/mm.h
index b976d9f..07f71c5 100644
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1191,6 +1191,8 @@ struct mm_walk {
void *private;
};

+int generic_walk_page_test_no_skip(unsigned long start, unsigned long end,
+ struct mm_walk *walk);
int walk_page_range(unsigned long addr, unsigned long end,
struct mm_walk *walk);
int walk_page_vma(struct vm_area_struct *vma, struct mm_walk *walk);
diff --git a/mm/pagewalk.c b/mm/pagewalk.c
index 75c1f28..14f38d5 100644
--- a/mm/pagewalk.c
+++ b/mm/pagewalk.c
@@ -206,6 +206,11 @@ static int __walk_page_range(unsigned long start, unsigned long end,
return err;
}

+int generic_walk_page_test_no_skip(unsigned long start, unsigned long end,
+ struct mm_walk *walk)
+{
+ return 0;
+}
/**
* walk_page_range - walk page table with caller specific callbacks
*
--
2.2.2

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