mm: add comments to explain mm_struct fields

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

Signed-off-by: Christoph Lameter <cl@linux.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

diff --git a/include/linux/mm_types.h b/include/linux/mm_types.h
index 1615a15add8e922faa12c01456002c2d19bd46f5..9e293907352947c597961e90d922f9dc06f2ddf7 100644 (file)
--- a/include/linux/mm_types.h
+++ b/include/linux/mm_types.h
@@ -293,8 +293,15 @@ 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;