blk-mq: really fix plug list flushing for nomerge queues

[linux-2.6-block.git] / mm / Kconfig.debug

diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 5c50b238b7705a5a4e2ce9a1845e11fc76ec4503..22f4cd96acb0d3a320c9a6440d63585f0dfd6057 100644 (file)
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -79,3 +79,16 @@ config PAGE_POISONING_ZERO
           Enabling page poisoning with this option will disable hibernation
 
           If unsure, say N
+       bool
+
+config DEBUG_PAGE_REF
+       bool "Enable tracepoint to track down page reference manipulation"
+       depends on DEBUG_KERNEL
+       depends on TRACEPOINTS
+       ---help---
+         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.