mm: add comments to explain mm_struct fields

Add comments to explain the page statistics field in the mm_struct.

[akpm@linux-foundation.org: add missing ;]
Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 2 deletions

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index f3175830cc7..3e01a19a91e 100644
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -304,8 +304,15 @@ struct mm_struct {
         unsigned long hiwater_rss;      /* High-watermark of RSS usage */
         unsigned long hiwater_vm;       /* High-water virtual memory usage */
 
-        unsigned long total_vm, locked_vm, pinned_vm, shared_vm, exec_vm;
-        unsigned long stack_vm, reserved_vm, def_flags, nr_ptes;
+        unsigned long total_vm;         /* Total pages mapped */
+        unsigned long locked_vm;        /* Pages that have PG_mlocked set */
+        unsigned long pinned_vm;        /* Refcount permanently increased */
+        unsigned long shared_vm;        /* Shared pages (files) */
+        unsigned long exec_vm;          /* VM_EXEC & ~VM_WRITE */
+        unsigned long stack_vm;         /* VM_GROWSUP/DOWN */
+        unsigned long reserved_vm;      /* VM_RESERVED|VM_IO pages */
+        unsigned long def_flags;
+        unsigned long nr_ptes;          /* Page table pages */
         unsigned long start_code, end_code, start_data, end_data;
         unsigned long start_brk, brk, start_stack;
         unsigned long arg_start, arg_end, env_start, env_end;