---

yaml
---
r: 54187
b: refs/heads/master
c: b813e93
h: refs/heads/master
i:
  54185: fc79c9e
  54183: fc50255
v: v3

[refs]

@@ -1,2 +1,2 @@
 ---
-refs/heads/master: f79f177c25016647cc92ffac8afa7cb96ce47011
+refs/heads/master: b813e931b4c8235bb42e301096ea97dbdee3e8fe

trunk/Documentation/filesystems/proc.txt

@@ -122,21 +122,22 @@ subdirectory has the entries listed in Table 1-1.
 
 Table 1-1: Process specific entries in /proc 
 ..............................................................................
- File    Content                                        
- cmdline Command line arguments                         
- cpu	 Current and last cpu in which it was executed		(2.4)(smp)
- cwd	 Link to the current working directory
- environ Values of environment variables      
- exe	 Link to the executable of this process
- fd      Directory, which contains all file descriptors 
- maps	 Memory maps to executables and library files		(2.4)
- mem     Memory held by this process                    
- root	 Link to the root directory of this process
- 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
+ File		Content
+ clear_refs	Clears page referenced bits shown in smaps output
+ cmdline	Command line arguments
+ cpu		Current and last cpu in which it was executed	(2.4)(smp)
+ cwd		Link to the current working directory
+ environ	Values of environment variables
+ exe		Link to the executable of this process
+ fd		Directory, which contains all file descriptors
+ maps		Memory maps to executables and library files	(2.4)
+ mem		Memory held by this process
+ root		Link to the root directory of this process
+ 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, the rss size for each mapped file
 ..............................................................................
 
 For example, to get the status information of a process, all you have to do is

trunk/fs/proc/base.c

@@ -715,6 +715,40 @@ static const struct file_operations proc_oom_adjust_operations = {
 	.write		= oom_adjust_write,
 };
 
+static ssize_t clear_refs_write(struct file *file, const char __user *buf,
+				size_t count, loff_t *ppos)
+{
+	struct task_struct *task;
+	char buffer[PROC_NUMBUF], *end;
+	struct mm_struct *mm;
+
+	memset(buffer, 0, sizeof(buffer));
+	if (count > sizeof(buffer) - 1)
+		count = sizeof(buffer) - 1;
+	if (copy_from_user(buffer, buf, count))
+		return -EFAULT;
+	if (!simple_strtol(buffer, &end, 0))
+		return -EINVAL;
+	if (*end == '\n')
+		end++;
+	task = get_proc_task(file->f_path.dentry->d_inode);
+	if (!task)
+		return -ESRCH;
+	mm = get_task_mm(task);
+	if (mm) {
+		clear_refs_smap(mm);
+		mmput(mm);
+	}
+	put_task_struct(task);
+	if (end - buffer == 0)
+		return -EIO;
+	return end - buffer;
+}
+
+static struct file_operations proc_clear_refs_operations = {
+	.write		= clear_refs_write,
+};
+
 #ifdef CONFIG_AUDITSYSCALL
 #define TMPBUFLEN 21
 static ssize_t proc_loginuid_read(struct file * file, char __user * buf,
@@ -1851,6 +1885,7 @@ static struct pid_entry tgid_base_stuff[] = {
 	REG("mounts",     S_IRUGO, mounts),
 	REG("mountstats", S_IRUSR, mountstats),
 #ifdef CONFIG_MMU
+	REG("clear_refs", S_IWUSR, clear_refs),
 	REG("smaps",      S_IRUGO, smaps),
 #endif
 #ifdef CONFIG_SECURITY
@@ -2132,6 +2167,7 @@ static struct pid_entry tid_base_stuff[] = {
 	LNK("exe",       exe),
 	REG("mounts",    S_IRUGO, mounts),
 #ifdef CONFIG_MMU
+	REG("clear_refs", S_IWUSR, clear_refs),
 	REG("smaps",     S_IRUGO, smaps),
 #endif
 #ifdef CONFIG_SECURITY

trunk/fs/proc/task_mmu.c

@@ -195,7 +195,7 @@ static int show_map_internal(struct seq_file *m, void *v, struct mem_size_stats
 			   "Shared_Dirty:   %8lu kB\n"
 			   "Private_Clean:  %8lu kB\n"
 			   "Private_Dirty:  %8lu kB\n"
-			   "Pgs_Referenced: %8lu kB\n",
+			   "Referenced:     %8lu kB\n",
 			   (vma->vm_end - vma->vm_start) >> 10,
 			   mss->resident >> 10,
 			   mss->shared_clean  >> 10,
@@ -214,9 +214,9 @@ static int show_map(struct seq_file *m, void *v)
 	return show_map_internal(m, v, NULL);
 }
 
-static void smaps_one_pmd(struct vm_area_struct *vma, pmd_t *pmd,
-			  unsigned long addr, unsigned long end,
-			  void *private)
+static void smaps_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+			    unsigned long addr, unsigned long end,
+			    void *private)
 {
 	struct mem_size_stats *mss = private;
 	pte_t *pte, ptent;
@@ -254,8 +254,34 @@ static void smaps_one_pmd(struct vm_area_struct *vma, pmd_t *pmd,
 	cond_resched();
 }
 
-static inline void for_each_pmd_in_pud(struct pmd_walker *walker, pud_t *pud,
-				       unsigned long addr, unsigned long end)
+static void clear_refs_pte_range(struct vm_area_struct *vma, pmd_t *pmd,
+				 unsigned long addr, unsigned long end,
+				 void *private)
+{
+	pte_t *pte, ptent;
+	spinlock_t *ptl;
+	struct page *page;
+
+	pte = pte_offset_map_lock(vma->vm_mm, pmd, addr, &ptl);
+	for (; addr != end; pte++, addr += PAGE_SIZE) {
+		ptent = *pte;
+		if (!pte_present(ptent))
+			continue;
+
+		page = vm_normal_page(vma, addr, ptent);
+		if (!page)
+			continue;
+
+		/* Clear accessed and referenced bits. */
+		ptep_test_and_clear_young(vma, addr, pte);
+		ClearPageReferenced(page);
+	}
+	pte_unmap_unlock(pte - 1, ptl);
+	cond_resched();
+}
+
+static inline void walk_pmd_range(struct pmd_walker *walker, pud_t *pud,
+				  unsigned long addr, unsigned long end)
 {
 	pmd_t *pmd;
 	unsigned long next;
@@ -269,8 +295,8 @@ static inline void for_each_pmd_in_pud(struct pmd_walker *walker, pud_t *pud,
 	}
 }
 
-static inline void for_each_pud_in_pgd(struct pmd_walker *walker, pgd_t *pgd,
-				       unsigned long addr, unsigned long end)
+static inline void walk_pud_range(struct pmd_walker *walker, pgd_t *pgd,
+				  unsigned long addr, unsigned long end)
 {
 	pud_t *pud;
 	unsigned long next;
@@ -280,15 +306,24 @@ static inline void for_each_pud_in_pgd(struct pmd_walker *walker, pgd_t *pgd,
 		next = pud_addr_end(addr, end);
 		if (pud_none_or_clear_bad(pud))
 			continue;
-		for_each_pmd_in_pud(walker, pud, addr, next);
+		walk_pmd_range(walker, pud, addr, next);
 	}
 }
 
-static inline void for_each_pmd(struct vm_area_struct *vma,
-				void (*action)(struct vm_area_struct *, pmd_t *,
-					       unsigned long, unsigned long,
-					       void *),
-				void *private)
+/*
+ * walk_page_range - walk the page tables of a VMA with a callback
+ * @vma - VMA to walk
+ * @action - callback invoked for every bottom-level (PTE) page table
+ * @private - private data passed to the callback function
+ *
+ * Recursively walk the page table for the memory area in a VMA, calling
+ * a callback for every bottom-level (PTE) page table.
+ */
+static inline void walk_page_range(struct vm_area_struct *vma,
+				   void (*action)(struct vm_area_struct *,
+						  pmd_t *, unsigned long,
+						  unsigned long, void *),
+				   void *private)
 {
 	unsigned long addr = vma->vm_start;
 	unsigned long end = vma->vm_end;
@@ -305,7 +340,7 @@ static inline void for_each_pmd(struct vm_area_struct *vma,
 		next = pgd_addr_end(addr, end);
 		if (pgd_none_or_clear_bad(pgd))
 			continue;
-		for_each_pud_in_pgd(&walker, pgd, addr, next);
+		walk_pud_range(&walker, pgd, addr, next);
 	}
 }
 
@@ -316,10 +351,22 @@ static int show_smap(struct seq_file *m, void *v)
 
 	memset(&mss, 0, sizeof mss);
 	if (vma->vm_mm && !is_vm_hugetlb_page(vma))
-		for_each_pmd(vma, smaps_one_pmd, &mss);
+		walk_page_range(vma, smaps_pte_range, &mss);
 	return show_map_internal(m, v, &mss);
 }
 
+void clear_refs_smap(struct mm_struct *mm)
+{
+	struct vm_area_struct *vma;
+
+	down_read(&mm->mmap_sem);
+	for (vma = mm->mmap; vma; vma = vma->vm_next)
+		if (vma->vm_mm && !is_vm_hugetlb_page(vma))
+			walk_page_range(vma, clear_refs_pte_range, NULL);
+	flush_tlb_mm(mm);
+	up_read(&mm->mmap_sem);
+}
+
 static void *m_start(struct seq_file *m, loff_t *pos)
 {
 	struct proc_maps_private *priv = m->private;

trunk/include/linux/proc_fs.h

@@ -104,6 +104,7 @@ int proc_pid_readdir(struct file * filp, void * dirent, filldir_t filldir);
 unsigned long task_vsize(struct mm_struct *);
 int task_statm(struct mm_struct *, int *, int *, int *, int *);
 char *task_mem(struct mm_struct *, char *);
+void clear_refs_smap(struct mm_struct *mm);
 
 extern struct proc_dir_entry *create_proc_entry(const char *name, mode_t mode,
 						struct proc_dir_entry *parent);