mm: debug-pagealloc: fix kconfig dependency warning

Fix kconfig dependency warning to satisfy dependencies:

warning: (PAGE_POISONING) selects DEBUG_PAGEALLOC which has unmet
direct dependencies (DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC &&
(!HIBERNATION || !PPC && !SPARC) && !KMEMCHECK)

Signed-off-by: Akinobu Mita <akinobu.mita@gmail.com>
Cc: Randy Dunlap <randy.dunlap@oracle.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

mm/Kconfig.debug

@@ -1,27 +1,24 @@
 config DEBUG_PAGEALLOC
 	bool "Debug page memory allocations"
-	depends on DEBUG_KERNEL && ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on !HIBERNATION || !PPC && !SPARC
+	depends on DEBUG_KERNEL
+	depends on !HIBERNATION || ARCH_SUPPORTS_DEBUG_PAGEALLOC && !PPC && !SPARC
 	depends on !KMEMCHECK
+	select PAGE_POISONING if !ARCH_SUPPORTS_DEBUG_PAGEALLOC
 	---help---
 	  Unmap pages from the kernel linear mapping after free_pages().
 	  This results in a large slowdown, but helps to find certain types
 	  of memory corruption.
 
+	  For architectures which don't enable ARCH_SUPPORTS_DEBUG_PAGEALLOC,
+	  fill the pages with poison patterns after free_pages() and verify
+	  the patterns before alloc_pages().  Additionally,
+	  this option cannot be enabled in combination with hibernation as
+	  that would result in incorrect warnings of memory corruption after
+	  a resume because free pages are not saved to the suspend image.
+
 config WANT_PAGE_DEBUG_FLAGS
 	bool
 
 config PAGE_POISONING
-	bool "Debug page memory allocations"
-	depends on DEBUG_KERNEL && !ARCH_SUPPORTS_DEBUG_PAGEALLOC
-	depends on !HIBERNATION
-	select DEBUG_PAGEALLOC
+	bool
 	select WANT_PAGE_DEBUG_FLAGS
-	---help---
-	   Fill the pages with poison patterns after free_pages() and verify
-	   the patterns before alloc_pages(). This results in a large slowdown,
-	   but helps to find certain types of memory corruption.
-
-	   This option cannot be enabled in combination with hibernation as
-	   that would result in incorrect warnings of memory corruption after
-	   a resume because free pages are not saved to the suspend image.