linux-kernel - [PATCH] mm: remove redundant 'default n' from Kconfig-s

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Date:   Fri, 12 Apr 2019 12:04:12 +0200
From:   Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org
Subject: [PATCH] mm: remove redundant 'default n' from Kconfig-s

'default n' is the default value for any bool or tristate Kconfig
setting so there is no need to write it explicitly.

Also since commit f467c5640c29 ("kconfig: only write '# CONFIG_FOO
is not set' for visible symbols") the Kconfig behavior is the same
regardless of 'default n' being present or not:

    ...
    One side effect of (and the main motivation for) this change is making
    the following two definitions behave exactly the same:
    
        config FOO
                bool
    
        config FOO
                bool
                default n
    
    With this change, neither of these will generate a
    '# CONFIG_FOO is not set' line (assuming FOO isn't selected/implied).
    That might make it clearer to people that a bare 'default n' is
    redundant.
    ...

Signed-off-by: Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>
---
 mm/Kconfig       |   11 -----------
 mm/Kconfig.debug |    1 -
 2 files changed, 12 deletions(-)

Index: b/mm/Kconfig
===================================================================
--- a/mm/Kconfig	2019-04-12 12:01:55.622124712 +0200
+++ b/mm/Kconfig	2019-04-12 12:01:55.598124711 +0200
@@ -161,7 +161,6 @@ config MEMORY_HOTPLUG_SPARSE
 
 config MEMORY_HOTPLUG_DEFAULT_ONLINE
         bool "Online the newly added memory blocks by default"
-        default n
         depends on MEMORY_HOTPLUG
         help
 	  This option sets the default policy setting for memory hotplug
@@ -439,7 +438,6 @@ config NEED_PER_CPU_KM
 
 config CLEANCACHE
 	bool "Enable cleancache driver to cache clean pages if tmem is present"
-	default n
 	help
 	  Cleancache can be thought of as a page-granularity victim cache
 	  for clean pages that the kernel's pageframe replacement algorithm
@@ -463,7 +461,6 @@ config CLEANCACHE
 config FRONTSWAP
 	bool "Enable frontswap to cache swap pages if tmem is present"
 	depends on SWAP
-	default n
 	help
 	  Frontswap is so named because it can be thought of as the opposite
 	  of a "backing" store for a swap device.  The data is stored into
@@ -535,7 +532,6 @@ config ZSWAP
 	depends on FRONTSWAP && CRYPTO=y
 	select CRYPTO_LZO
 	select ZPOOL
-	default n
 	help
 	  A lightweight compressed cache for swap pages.  It takes
 	  pages that are in the process of being swapped out and attempts to
@@ -552,14 +548,12 @@ config ZSWAP
 
 config ZPOOL
 	tristate "Common API for compressed memory storage"
-	default n
 	help
 	  Compressed memory storage API.  This allows using either zbud or
 	  zsmalloc.
 
 config ZBUD
 	tristate "Low (Up to 2x) density storage for compressed pages"
-	default n
 	help
 	  A special purpose allocator for storing compressed pages.
 	  It is designed to store up to two compressed pages per physical
@@ -570,7 +564,6 @@ config ZBUD
 config Z3FOLD
 	tristate "Up to 3x density storage for compressed pages"
 	depends on ZPOOL
-	default n
 	help
 	  A special purpose allocator for storing compressed pages.
 	  It is designed to store up to three compressed pages per physical
@@ -580,7 +573,6 @@ config Z3FOLD
 config ZSMALLOC
 	tristate "Memory allocator for compressed pages"
 	depends on MMU
-	default n
 	help
 	  zsmalloc is a slab-based memory allocator designed to store
 	  compressed RAM pages.  zsmalloc uses virtual memory mapping
@@ -631,7 +623,6 @@ config MAX_STACK_SIZE_MB
 
 config DEFERRED_STRUCT_PAGE_INIT
 	bool "Defer initialisation of struct pages to kthreads"
-	default n
 	depends on SPARSEMEM
 	depends on !NEED_PER_CPU_KM
 	depends on 64BIT
@@ -743,7 +734,6 @@ config ARCH_HAS_PKEYS
 
 config PERCPU_STATS
 	bool "Collect percpu memory statistics"
-	default n
 	help
 	  This feature collects and exposes statistics via debugfs. The
 	  information includes global and per chunk statistics, which can
@@ -751,7 +741,6 @@ config PERCPU_STATS
 
 config GUP_BENCHMARK
 	bool "Enable infrastructure for get_user_pages_fast() benchmarking"
-	default n
 	help
 	  Provides /sys/kernel/debug/gup_benchmark that helps with testing
 	  performance of get_user_pages_fast().
Index: b/mm/Kconfig.debug
===================================================================
--- a/mm/Kconfig.debug	2019-04-01 13:12:35.691272564 +0200
+++ b/mm/Kconfig.debug	2019-04-12 12:02:12.686125141 +0200
@@ -33,7 +33,6 @@ config DEBUG_PAGEALLOC
 
 config DEBUG_PAGEALLOC_ENABLE_DEFAULT
 	bool "Enable debug page memory allocations by default?"
-	default n
 	depends on DEBUG_PAGEALLOC
 	---help---
 	  Enable debug page memory allocations by default? This value