diff --git a/Documentation/filesystems/proc.txt b/Documentation/filesystems/proc.txt
index 7aaf09b86a552210584f6e346ad903b10a9cb0b6..3f4b226572e7fd39cea5cd6547dd80a2627f928b 100644
--- a/Documentation/filesystems/proc.txt
+++ b/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
diff --git a/fs/proc/base.c b/fs/proc/base.c
index 989af5e55d1bec761b8a2604d6e8528713d7d8da..ec158dd02b3ac2b758fbbf527820c1f0f83a486a 100644
--- a/fs/proc/base.c
+++ b/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
diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 199088ee969b1ec956fb85337e614c9ec42c92ab..4008c060f7ef1b2b9ddc51154d30e1ec865906a5 100644
--- a/fs/proc/task_mmu.c
+++ b/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;
diff --git a/include/linux/proc_fs.h b/include/linux/proc_fs.h
index be4652a0545a0226cb23264e923f9692968e866b..f4f7a63cae1f858f3779adf9b607d526b3fa038b 100644
--- a/include/linux/proc_fs.h
+++ b/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);