proc/maps: make vm_is_stack() logic namespace-friendly

- Rename vm_is_stack() to task_of_stack() and change it to return
  "struct task_struct *" rather than the global (and thus wrong in
  general) pid_t.

- Add the new pid_of_stack() helper which calls task_of_stack() and
  uses the right namespace to report the correct pid_t.

  Unfortunately we need to define this helper twice, in task_mmu.c
  and in task_nommu.c. perhaps it makes sense to add fs/proc/util.c
  and move at least pid_of_stack/task_of_stack there to avoid the
  code duplication.

- Change show_map_vma() and show_numa_map() to use the new helper.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Cc: Alexander Viro <viro@zeniv.linux.org.uk>
Cc: Cyrill Gorcunov <gorcunov@openvz.org>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Greg Ungerer <gerg@uclinux.org>
Cc: "Kirill A. Shutemov" <kirill.shutemov@linux.intel.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

diff --git a/fs/proc/task_mmu.c b/fs/proc/task_mmu.c
index 4793e4a..adddf69 100644 (file)
--- a/fs/proc/task_mmu.c
+++ b/fs/proc/task_mmu.c
@@ -261,13 +261,31 @@ static int do_maps_open(struct inode *inode, struct file *file,
                                sizeof(struct proc_maps_private));
 }
 
+static pid_t pid_of_stack(struct proc_maps_private *priv,
+                               struct vm_area_struct *vma, bool is_pid)
+{
+       struct inode *inode = priv->inode;
+       struct task_struct *task;
+       pid_t ret = 0;
+
+       rcu_read_lock();
+       task = pid_task(proc_pid(inode), PIDTYPE_PID);
+       if (task) {
+               task = task_of_stack(task, vma, is_pid);
+               if (task)
+                       ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info);
+       }
+       rcu_read_unlock();
+
+       return ret;
+}
+
 static void
 show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
 {
        struct mm_struct *mm = vma->vm_mm;
        struct file *file = vma->vm_file;
        struct proc_maps_private *priv = m->private;
-       struct task_struct *task = priv->task;
        vm_flags_t flags = vma->vm_flags;
        unsigned long ino = 0;
        unsigned long long pgoff = 0;
@@ -332,8 +350,7 @@ show_map_vma(struct seq_file *m, struct vm_area_struct *vma, int is_pid)
                        goto done;
                }
 
-               tid = vm_is_stack(task, vma, is_pid);
-
+               tid = pid_of_stack(priv, vma, is_pid);
                if (tid != 0) {
                        /*
                         * Thread stack in /proc/PID/task/TID/maps or
@@ -1446,7 +1463,7 @@ static int show_numa_map(struct seq_file *m, void *v, int is_pid)
        } else if (vma->vm_start <= mm->brk && vma->vm_end >= mm->start_brk) {
                seq_puts(m, " heap");
        } else {
-               pid_t tid = vm_is_stack(task, vma, is_pid);
+               pid_t tid = pid_of_stack(proc_priv, vma, is_pid);
                if (tid != 0) {
                        /*
                         * Thread stack in /proc/PID/task/TID/maps or

diff --git a/fs/proc/task_nommu.c b/fs/proc/task_nommu.c
index f36e213..599ec2e 100644 (file)
--- a/fs/proc/task_nommu.c
+++ b/fs/proc/task_nommu.c
@@ -123,6 +123,25 @@ unsigned long task_statm(struct mm_struct *mm,
        return size;
 }
 
+static pid_t pid_of_stack(struct proc_maps_private *priv,
+                               struct vm_area_struct *vma, bool is_pid)
+{
+       struct inode *inode = priv->inode;
+       struct task_struct *task;
+       pid_t ret = 0;
+
+       rcu_read_lock();
+       task = pid_task(proc_pid(inode), PIDTYPE_PID);
+       if (task) {
+               task = task_of_stack(task, vma, is_pid);
+               if (task)
+                       ret = task_pid_nr_ns(task, inode->i_sb->s_fs_info);
+       }
+       rcu_read_unlock();
+
+       return ret;
+}
+
 /*
  * display a single VMA to a sequenced file
  */
@@ -163,7 +182,7 @@ static int nommu_vma_show(struct seq_file *m, struct vm_area_struct *vma,
                seq_pad(m, ' ');
                seq_path(m, &file->f_path, "");
        } else if (mm) {
-               pid_t tid = vm_is_stack(priv->task, vma, is_pid);
+               pid_t tid = pid_of_stack(priv, vma, is_pid);
 
                if (tid != 0) {
                        seq_pad(m, ' ');

diff --git a/include/linux/mm.h b/include/linux/mm.h
index 0f4196a..28df707 100644 (file)
--- a/include/linux/mm.h
+++ b/include/linux/mm.h
@@ -1247,8 +1247,8 @@ static inline int stack_guard_page_end(struct vm_area_struct *vma,
                !vma_growsup(vma->vm_next, addr);
 }
 
-extern pid_t
-vm_is_stack(struct task_struct *task, struct vm_area_struct *vma, int in_group);
+extern struct task_struct *task_of_stack(struct task_struct *task,
+                               struct vm_area_struct *vma, bool in_group);
 
 extern unsigned long move_page_tables(struct vm_area_struct *vma,
                unsigned long old_addr, struct vm_area_struct *new_vma,

diff --git a/mm/util.c b/mm/util.c
index 093c973..fec39d4 100644 (file)
--- a/mm/util.c
+++ b/mm/util.c
@@ -170,32 +170,25 @@ static int vm_is_stack_for_task(struct task_struct *t,
 /*
  * Check if the vma is being used as a stack.
  * If is_group is non-zero, check in the entire thread group or else
- * just check in the current task. Returns the pid of the task that
- * the vma is stack for.
+ * just check in the current task. Returns the task_struct of the task
+ * that the vma is stack for. Must be called under rcu_read_lock().
  */
-pid_t vm_is_stack(struct task_struct *task,
-                 struct vm_area_struct *vma, int in_group)
+struct task_struct *task_of_stack(struct task_struct *task,
+                               struct vm_area_struct *vma, bool in_group)
 {
-       pid_t ret = 0;
-
        if (vm_is_stack_for_task(task, vma))
-               return task->pid;
+               return task;
 
        if (in_group) {
                struct task_struct *t;
 
-               rcu_read_lock();
                for_each_thread(task, t) {
-                       if (vm_is_stack_for_task(t, vma)) {
-                               ret = t->pid;
-                               goto done;
-                       }
+                       if (vm_is_stack_for_task(t, vma))
+                               return t;
                }
-done:
-               rcu_read_unlock();
        }
 
-       return ret;
+       return NULL;
 }
 
 #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)