/proc/pid/smaps: show VM_SOFTDIRTY flag in VmFlags line

This flag shows that the VMA is "newly created" and thus represents
"dirty" in the task's VM.

You can clear it by "echo 4 > /proc/pid/clear_refs."

Signed-off-by: Naoya Horiguchi <n-horiguchi@ah.jp.nec.com>
Cc: Wu Fengguang <fengguang.wu@intel.com>
Cc: Pavel Emelyanov <xemul@parallels.com>
Acked-by: Cyrill Gorcunov <gorcunov@openvz.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

Documentation/filesystems/proc.txt

@@ -460,6 +460,7 @@ manner. The codes are the following:
     nl  - non-linear mapping
     ar  - architecture specific flag
     dd  - do not include area into core dump
+    sd  - soft-dirty flag
     mm  - mixed map area
     hg  - huge page advise flag
     nh  - no-huge page advise flag

fs/proc/task_mmu.c

@@ -561,6 +561,9 @@ static void show_smap_vma_flags(struct seq_file *m, struct vm_area_struct *vma)
 		[ilog2(VM_NONLINEAR)]	= "nl",
 		[ilog2(VM_ARCH_1)]	= "ar",
 		[ilog2(VM_DONTDUMP)]	= "dd",
+#ifdef CONFIG_MEM_SOFT_DIRTY
+		[ilog2(VM_SOFTDIRTY)]	= "sd",
+#endif
 		[ilog2(VM_MIXEDMAP)]	= "mm",
 		[ilog2(VM_HUGEPAGE)]	= "hg",
 		[ilog2(VM_NOHUGEPAGE)]	= "nh",