Signed-off-by: David Singleton <dsingleton@mvista.com>
Signed-off-by: Joe Green <jgreen@mvista.com>

    Add variation of /proc/PID/smaps called /proc/PID/pagemaps.
    Shows reference counts for individual pages instead of aggregate totals.
    Allows more detailed memory usage information for memory analysis tools.
    An example of the output shows the shared text VMA for ld.so and
    the share depths of the pages in the VMA.

a7f4b000-a7f65000 r-xp 00000000 00:0d 19185826   /lib/ld-2.5.90.so
 11 11 11 11 11 11 11 11 11 13 13 13 13 13 13 13 8 8 8 13 13 13 13 13 13 13


 Documentation/filesystems/proc.txt |    3 -
 fs/proc/base.c                     |    2 
 fs/proc/internal.h                 |    5 -
 fs/proc/task_mmu.c                 |  110 +++++++++++++++++++++++++++++++++++++
 4 files changed, 115 insertions(+), 5 deletions(-)

Index: linux-2.6.19/Documentation/filesystems/proc.txt
===================================================================
--- linux-2.6.19.orig/Documentation/filesystems/proc.txt
+++ linux-2.6.19/Documentation/filesystems/proc.txt
@@ -130,12 +130,13 @@ Table 1-1: Process specific entries in /
  fd      Directory, which contains all file descriptors 
  maps	 Memory maps to executables and library files		(2.4)
  mem     Memory held by this process                    
+ pagemaps Based on maps, presents page ref counts for each mapped file
  root	 Link to the root directory of this process
+ smaps	 Extension based on maps, presenting the rss size for each mapped file
  stat    Process status                                 
  statm   Process memory status information              
  status  Process status in human readable form          
  wchan   If CONFIG_KALLSYMS is set, a pre-decoded wchan
- smaps	 Extension based on maps, presenting the rss size for each mapped file
 ..............................................................................
 
 For example, to get the status information of a process, all you have to do is
Index: linux-2.6.19/fs/proc/base.c
===================================================================
--- linux-2.6.19.orig/fs/proc/base.c
+++ linux-2.6.19/fs/proc/base.c
@@ -1773,6 +1773,7 @@ static struct pid_entry tgid_base_stuff[
 	REG("mountstats", S_IRUSR, mountstats),
 #ifdef CONFIG_MMU
 	REG("smaps",      S_IRUGO, smaps),
+	REG("pagemaps",   S_IRUGO, pagemaps),
 #endif
 #ifdef CONFIG_SECURITY
 	DIR("attr",       S_IRUGO|S_IXUGO, attr_dir),
@@ -2047,6 +2048,7 @@ static struct pid_entry tid_base_stuff[]
 	REG("mounts",    S_IRUGO, mounts),
 #ifdef CONFIG_MMU
 	REG("smaps",     S_IRUGO, smaps),
+	REG("pagemaps",  S_IRUGO, pagemaps),
 #endif
 #ifdef CONFIG_SECURITY
 	DIR("attr",      S_IRUGO|S_IXUGO, attr_dir),
Index: linux-2.6.19/fs/proc/internal.h
===================================================================
--- linux-2.6.19.orig/fs/proc/internal.h
+++ linux-2.6.19/fs/proc/internal.h
@@ -41,10 +41,7 @@ extern int proc_pid_statm(struct task_st
 extern struct file_operations proc_maps_operations;
 extern struct file_operations proc_numa_maps_operations;
 extern struct file_operations proc_smaps_operations;
-
-extern struct file_operations proc_maps_operations;
-extern struct file_operations proc_numa_maps_operations;
-extern struct file_operations proc_smaps_operations;
+extern struct file_operations proc_pagemaps_operations;
 
 
 void free_proc_entry(struct proc_dir_entry *de);
Index: linux-2.6.19/fs/proc/task_mmu.c
===================================================================
--- linux-2.6.19.orig/fs/proc/task_mmu.c
+++ linux-2.6.19/fs/proc/task_mmu.c
@@ -429,6 +429,116 @@ static int do_maps_open(struct inode *in
 	return ret;
 }
 
+static void pagemaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+				unsigned long addr, unsigned long end,
+				struct seq_file *m)
+{
+	pte_t *pte, ptent;
+	spinlock_t *ptl;
+	struct page *page;
+	int mapcount = 0;
+
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	do {
+		ptent = *pte;
+		if (pte_present(ptent)) {
+			page = vm_normal_page(vma, addr, ptent);
+			if (page) {
+				if (pte_dirty(ptent))
+					mapcount = -page_mapcount(page);
+				else
+					mapcount = page_mapcount(page);
+			} else {
+				mapcount = 1;
+			}
+		}
+		seq_printf(m, " %d", mapcount);
+
+	} while (pte++, addr += PAGE_SIZE, addr != end);
+	seq_putc(m, '\n');
+
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+
+}
+
+static inline void pagemaps_pmd_range(struct vm_area_struct *vma, pud_t *pud,
+				unsigned long addr, unsigned long end,
+				struct seq_file *m)
+{
+	pmd_t *pmd;
+	unsigned long next;
+
+	pmd = pmd_offset(pud, addr);
+	do {
+		next = pmd_addr_end(addr, end);
+		if (pmd_none_or_clear_bad(pmd))
+			continue;
+		pagemaps_pte_range(vma, pmd, addr, next, m);
+	} while (pmd++, addr = next, addr != end);
+}
+
+static inline void pagemaps_pud_range(struct vm_area_struct *vma, pgd_t *pgd,
+				unsigned long addr, unsigned long end,
+				struct seq_file *m)
+{
+	pud_t *pud;
+	unsigned long next;
+
+	pud = pud_offset(pgd, addr);
+	do {
+		next = pud_addr_end(addr, end);
+		if (pud_none_or_clear_bad(pud))
+			continue;
+		pagemaps_pmd_range(vma, pud, addr, next, m);
+	} while (pud++, addr = next, addr != end);
+}
+
+static inline void pagemaps_pgd_range(struct vm_area_struct *vma,
+				unsigned long addr, unsigned long end,
+				struct seq_file *m)
+{
+	pgd_t *pgd;
+	unsigned long next;
+
+	pgd = pgd_offset(vma->vm_mm, addr);
+	do {
+		next = pgd_addr_end(addr, end);
+		if (pgd_none_or_clear_bad(pgd))
+			continue;
+		pagemaps_pud_range(vma, pgd, addr, next, m);
+	} while (pgd++, addr = next, addr != end);
+}
+
+static int show_pagemap(struct seq_file *m, void *v)
+{
+	struct vm_area_struct *vma = v;
+
+	show_map_internal(m, v, NULL);
+	if (vma->vm_mm && !is_vm_hugetlb_page(vma))
+		pagemaps_pgd_range(vma, vma->vm_start, vma->vm_end, m);
+	return 0;
+}
+
+static struct seq_operations proc_pid_pagemaps_op = {
+	.start	= m_start,
+	.next	= m_next,
+	.stop	= m_stop,
+	.show	= show_pagemap
+};
+
+static int pagemaps_open(struct inode *inode, struct file *file)
+{
+	return do_maps_open(inode, file, &proc_pid_pagemaps_op);
+}
+
+struct file_operations proc_pagemaps_operations = {
+	.open		= pagemaps_open,
+	.read		= seq_read,
+	.llseek		= seq_lseek,
+	.release	= seq_release_private,
+};
+
 static int maps_open(struct inode *inode, struct file *file)
 {
 	return do_maps_open(inode, file, &proc_pid_maps_op);
