/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 <[e-mail]>
Cc: Wu Fengguang <[e-mail]>
Cc: Pavel Emelyanov <[e-mail]>
Acked-by: Cyrill Gorcunov <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
Signed-off-by: Linus Torvalds <[e-mail]>

Documentation/filesystems/proc.txt

···
     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

···
 		[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",