fs/proc/task_mmu.c: fix Locked field in /proc/pid/smaps*

Thomas reports:
 "While looking around in /proc on my v4.14.52 system I noticed that all
  processes got a lot of "Locked" memory in /proc/*/smaps. A lot more
  memory than a regular user can usually lock with mlock().

  Commit 493b0e9 (in v4.14-rc1) seems to have changed the behavior
  of "Locked".

  Before that commit the code was like this. Notice the VM_LOCKED check.

           (vma->vm_flags & VM_LOCKED) ?
                (unsigned long)(mss.pss >> (10 + PSS_SHIFT)) : 0);

  After that commit Locked is now the same as Pss:

	  (unsigned long)(mss->pss >> (10 + PSS_SHIFT)));

  This looks like a mistake."

Indeed, the commit has added mss->pss_locked with the correct value that
depends on VM_LOCKED, but forgot to actually use it.  Fix it.

Link: http://lkml.kernel.org/r/[email protected]
Fixes: 493b0e9 ("mm: add /proc/pid/smaps_rollup")
Signed-off-by: Vlastimil Babka <[email protected]>
Reported-by: Thomas Lindroth <[email protected]>
Cc: Alexey Dobriyan <[email protected]>
Cc: Daniel Colascione <[email protected]>
Cc: <[email protected]>
Signed-off-by: Andrew Morton <[email protected]>
Signed-off-by: Linus Torvalds <[email protected]>

Author: tehcaster

fs/proc/task_mmu.c

@@ -831,7 +831,8 @@ static int show_smap(struct seq_file *m, void *v, int is_pid)
 		SEQ_PUT_DEC(" kB\nSwap:           ", mss->swap);
 		SEQ_PUT_DEC(" kB\nSwapPss:        ",
 						mss->swap_pss >> PSS_SHIFT);
-		SEQ_PUT_DEC(" kB\nLocked:         ", mss->pss >> PSS_SHIFT);
+		SEQ_PUT_DEC(" kB\nLocked:         ",
+						mss->pss_locked >> PSS_SHIFT);
 		seq_puts(m, " kB\n");
 	}
 	if (!rollup_mode) {