-mm/linux-next: procfs: Mark thread stack correctly in proc/<pid>/maps

Following is the updated patch with requested changes incorporated.

Boy, that's a lot of changes (below).  What does it all do?

Why did the sched.h inclusions get taken out again?

diff -puN Documentation/filesystems/proc.txt~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 Documentation/filesystems/proc.txt

Documentation/filesystems/proc.txt renamed from Documentation/filesystems/proc.txt~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 +0 -0

 The /proc/PID/task/TID/maps is a view of the virtual memory from the viewpoint of the individual tasks of a process. In this file you will see a mapping marked

Documentation/filesystems/proc.txt renamed from Documentation/filesystems/proc.txt~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 +15 -3

-as [stack:TID] only if that task sees it as a stack. This is a key difference
-from the content of /proc/PID/maps, where you will see all mappings that are
-being used as stack by all of those tasks.
+as [stack] if that task sees it as a stack. This is a key difference from the
+content of /proc/PID/maps, where you will see all mappings that are being used
+as stack by all of those tasks. Hence, for the example above, the task-level
+map, i.e. /proc/PID/task/TID/maps for thread 1001 will look like this:
+
+08048000-08049000 r-xp 00000000 03:00 8312       /opt/test
+08049000-0804a000 rw-p 00001000 03:00 8312       /opt/test
+0804a000-0806b000 rw-p 00000000 00:00 0          [heap]
+a7cb1000-a7cb2000 ---p 00000000 00:00 0
+a7cb2000-a7eb2000 rw-p 00000000 00:00 0
+a7eb2000-a7eb3000 ---p 00000000 00:00 0
+a7eb3000-a7ed5000 rw-p 00000000 00:00 0          [stack]
+a7ed5000-a8008000 r-xp 00000000 03:00 4222       /lib/libc.so.6
+a8008000-a800a000 r--p 00133000 03:00 4222       /lib/libc.so.6
+a800a000-a800b000 rw-p 00135000 03:00 4222       /lib/libc.so.6

fs/proc/task_mmu.c renamed from fs/proc/task_mmu.c~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 +32 -18

@@ -222,7 +222,7 @@ show_map_vma(struct seq_file *m, struct
        unsigned long start, end;
        dev_t dev = 0;
        int len;
-       const char *name;
+       const char *name = NULL;
 
        if (file) {
                struct inode *inode = vma->vm_file->f_path.dentry->d_inode;

@@ -256,33 +256,47 @@ show_map_vma(struct seq_file *m, struct
        if (file) {
                pad_len_spaces(m, len);
                seq_path(m, &file->f_path, "\n");
-               goto out;
+               goto done;
        }
 
        name = arch_vma_name(vma);
        if (!name) {
-               if (mm) {
-                       if (vma->vm_start <= mm->brk &&
-                                       vma->vm_end >= mm->start_brk) {
-                               name = "[heap]";
-                       } else {
-                               pid_t tid;
+               pid_t tid;
 
-                               tid = vm_is_stack(task, vma, is_pid);
-                               if (tid != 0) {
-                                       pad_len_spaces(m, len);
-                                       seq_printf(m, "[stack:%d]", tid);
-                               }
-                       }
-               } else {
+               if (!mm) {
                        name = "[vdso]";
+                       goto done;
+               }
+
+               if (vma->vm_start <= mm->brk &&
+                   vma->vm_end >= mm->start_brk) {
+                       name = "[heap]";
+                       goto done;
+               }
+
+               tid = vm_is_stack(task, vma, is_pid);
+
+               if (tid !=0) {
+                       /*
+                        * Thread stack in /proc/PID/task/TID/maps or
+                        * the main process stack.
+                        */
+                       if (!is_pid || (vma->vm_start <= mm->start_stack &&
+                           vma->vm_end >= mm->start_stack)) {
+                               name = "[stack]";
+                       } else {
+                               /* Thread stack in /proc/PID/maps */
+                               pad_len_spaces(m, len);
+                               seq_printf(m, "[stack:%d]", tid);
+                       }
                }
        }
+
+done:
        if (name) {
                pad_len_spaces(m, len);
                seq_puts(m, name);
        }
-out:
        seq_putc(m, '\n');
  }
 

@@ -1134,8 +1148,17 @@ static int show_numa_map(struct seq_file
                seq_printf(m, " heap");
        } else {
                pid_t tid = vm_is_stack(proc_priv->task, vma, is_pid);
-               if (tid != 0)
-                       seq_printf(m, " stack:%d", tid);
+               if (tid !=0) {
+                       /*

diff -puN mm/util.c~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 mm/util.c

mm/util.c renamed from mm/util.c~procfs-mark-thread-stack-correctly-in-proc-pid-maps-v3 +41 -0

@@ -239,6 +239,47 @@ void __vma_link_list(struct mm_struct *m
                next->vm_prev = vma;
  }
 
+/* Check if the vma is being used as a stack by this task */
+static int vm_is_stack_for_task(struct task_struct *t,
+                               struct vm_area_struct *vma)
+{
+       return (vma->vm_start <= KSTK_ESP(t) && vma->vm_end >= KSTK_ESP(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.
+ */
+pid_t vm_is_stack(struct task_struct *task,
+                 struct vm_area_struct *vma, int in_group)
+{
+       pid_t ret = 0;
+
+       if (vm_is_stack_for_task(task, vma))
+               return task->pid;
+
+       if (in_group) {
+               struct task_struct *t;
+               rcu_read_lock();
+               if (!pid_alive(task))
+                       goto done;
+
+               t = task;
+               do {
+                       if (vm_is_stack_for_task(t, vma)) {
+                               ret = t->pid;
+                               goto done;
+                       }
+               } while_each_thread(task, t);
+done:
+               rcu_read_unlock();
+       }
+
+       return ret;
+}
+
  #if defined(CONFIG_MMU) && !defined(HAVE_ARCH_PICK_MMAP_LAYOUT)
  void arch_pick_mmap_layout(struct mm_struct *mm)
  {

_

Quoted 1 line · On Tue, 13 Mar 2012 23:04:36 +0530 Siddhesh Poyarekar…

Following is the updated patch with requested changes incorporated.

Boy, that's a lot of changes (below).  What does it all do?

Quoted 7 lines · Andrew Morton

Quoted 1 line · On Tue, 13 Mar 2012 23:04:36 +0530 Siddhesh Poyarekar…

Following is the updated patch with requested changes incorporated.

Boy, that's a lot of changes (below).  What does it all do?

Hi,

Since this patch was included in the -mm tree on March 14th, I assumed that linux-next would get the patch in today's merge, but it hasn't. Is there something I am missing? Does the patch need additional review/acks that I need to request for?

Thanks,
Siddhesh

Thanks,
Siddhesh

--
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http://siddhesh.in
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Now it is:

mm/nommu.o: In function `vm_is_stack':
nommu.c:(.text+0x2178): multiple definition of `vm_is_stack' mm/util.o:util.c:(.text+0x2bc): first defined here make[2]: *** [mm/built-in.o] Error 1

http://kisskb.ellerman.id.au/kisskb/buildresult/5941188/

Quoted 7 lines · Paul Gortmaker

Now it is:

mm/nommu.o: In function `vm_is_stack':
nommu.c:(.text+0x2178): multiple definition of `vm_is_stack' mm/util.o:util.c:(.text+0x2bc): first defined here make[2]: *** [mm/built-in.o] Error 1

Quoted 1 line

http://kisskb.ellerman.id.au/kisskb/buildresult/5941188/

Looks like the problem is because this patch got included in linux-next 2 days ago:

http://git.kernel.org/?p=linux/kernel/git/next/linux-next.git;a=commitdiff;h=47d1ab583408e5b8e900c5080aec9bbcf210df22