On Thu, 3 Mar 2016 16:43:49 +0900 Joonsoo Kim [off-list ref] wrote:

quoted

Acked-by: Vlastimil Babka <redacted>

quoted

+config DEBUG_PAGE_REF
+       bool "Enable tracepoint to track down page reference manipulation"
+       depends on DEBUG_KERNEL
+       depends on TRACEPOINTS
+       ---help---
+         This is the feature to add tracepoint for tracking down page
reference
+         manipulation. This tracking is useful to diagnosis functional
failure
+         due to migration failure caused by page reference mismatch. Be

OK.

quoted

+         careful to turn on this feature because it could bloat some
kernel
+         text. In my configuration, it bloats 30 KB. Although kernel text
will
+         be bloated, there would be no runtime performance overhead if
+         tracepoint isn't enabled thanks to jump label.

I would just write something like:

Enabling this feature adds about 30 KB to the kernel code, but runtime
performance overhead is virtually none until the tracepoints are actually
enabled.

Okay, better!
Andrew, do you want fixup patch from me or could you simply handle it?

This?

--- a/mm/Kconfig.debug~mm-page_ref-add-tracepoint-to-track-down-page-reference-manipulation-fix-3-fix
+++ a/mm/Kconfig.debug

@@ -82,10 +82,9 @@ config DEBUG_PAGE_REF
 	depends on DEBUG_KERNEL
 	depends on TRACEPOINTS
 	---help---
-	  This is the feature to add tracepoint for tracking down page reference
-	  manipulation. This tracking is useful to diagnosis functional failure
-	  due to migration failure caused by page reference mismatch. Be
-	  careful to turn on this feature because it could bloat some kernel
-	  text. In my configuration, it bloats 30 KB. Although kernel text will
-	  be bloated, there would be no runtime performance overhead if
-	  tracepoint isn't enabled thanks to jump label.
+	  This is a feature to add tracepoint for tracking down page reference
+	  manipulation. This tracking is useful to diagnose functional failure
+	  due to migration failures caused by page reference mismatches.  Be
+	  careful when enabling this feature because it adds about 30 KB to the
+	  kernel code.  However the runtime performance overhead is virtually
+	  nil until the tracepoints are actually enabled.

_