mm/migrate: correct failure handling if !hugepage_migration_support()

[firefly-linux-kernel-4.4.55.git] / lib / Kconfig.debug

diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 6982094a7e74aa8c5daea87f90878174a8d746c1..900b63c1e899efc48c07d2126c2cf1451eca799f 100644 (file)
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -1584,8 +1584,16 @@ config DMA_API_DEBUG
          With this option you will be able to detect common bugs in device
          drivers like double-freeing of DMA mappings or freeing mappings that
          were never allocated.
-         This option causes a performance degredation.  Use only if you want
-         to debug device drivers. If unsure, say N.
+
+         This also attempts to catch cases where a page owned by DMA is
+         accessed by the cpu in a way that could cause data corruption.  For
+         example, this enables cow_user_page() to check that the source page is
+         not undergoing DMA.
+
+         This option causes a performance degradation.  Use only if you want to
+         debug device drivers and dma interactions.
+
+         If unsure, say N.
 
 source "samples/Kconfig"