[PATCH] mm: Kconfig: reorganize misplaced mm options

[PATCH] mm: Kconfig: reorganize misplaced mm options

[Vlastimil Babka]

After commits 7b42f1041c98 ("mm: Kconfig: move swap and slab config
options to the MM section") and 519bcb797907 ("mm: Kconfig: group swap,
slab, hotplug and thp options into submenus") we now have nicely
organized mm related config options. I have noticed some that were still
misplaced, so this moves them from various places into the new structure:

VM_EVENT_COUNTERS, COMPAT_BRK, MMAP_ALLOW_UNINITIALIZED to mm/Kconfig
and general MM section.

SLUB_STATS to mm/Kconfig and the slab submenu.

DEBUG_SLAB, SLUB_DEBUG, SLUB_DEBUG_ON to mm/Kconfig.debug and the Kernel
hacking / Memory Debugging submenu.

Signed-off-by: Vlastimil Babka <vbabka@suse.cz>
---
 init/Kconfig      | 53 --------------------------------------------
 lib/Kconfig.debug | 34 ----------------------------
 mm/Kconfig        | 56 +++++++++++++++++++++++++++++++++++++++++++++++
 mm/Kconfig.debug  | 31 ++++++++++++++++++++++++++
 4 files changed, 87 insertions(+), 87 deletions(-)

diff --git a/init/Kconfig b/init/Kconfig
index 1d2ecd227f4b..0cff02738290 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1828,59 +1828,6 @@ config DEBUG_PERF_USE_VMALLOC
 
 endmenu
 
-config VM_EVENT_COUNTERS
-	default y
-	bool "Enable VM event counters for /proc/vmstat" if EXPERT
-	help
-	  VM event counters are needed for event counts to be shown.
-	  This option allows the disabling of the VM event counters
-	  on EXPERT systems.  /proc/vmstat will only show page counts
-	  if VM event counters are disabled.
-
-config SLUB_DEBUG
-	default y
-	bool "Enable SLUB debugging support" if EXPERT
-	depends on SLUB && SYSFS
-	help
-	  SLUB has extensive debug support features. Disabling these can
-	  result in significant savings in code size. This also disables
-	  SLUB sysfs support. /sys/slab will not exist and there will be
-	  no support for cache validation etc.
-
-config COMPAT_BRK
-	bool "Disable heap randomization"
-	default y
-	help
-	  Randomizing heap placement makes heap exploits harder, but it
-	  also breaks ancient binaries (including anything libc5 based).
-	  This option changes the bootup default to heap randomization
-	  disabled, and can be overridden at runtime by setting
-	  /proc/sys/kernel/randomize_va_space to 2.
-
-	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
-
-config MMAP_ALLOW_UNINITIALIZED
-	bool "Allow mmapped anonymous memory to be uninitialized"
-	depends on EXPERT && !MMU
-	default n
-	help
-	  Normally, and according to the Linux spec, anonymous memory obtained
-	  from mmap() has its contents cleared before it is passed to
-	  userspace.  Enabling this config option allows you to request that
-	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
-	  providing a huge performance boost.  If this option is not enabled,
-	  then the flag will be ignored.
-
-	  This is taken advantage of by uClibc's malloc(), and also by
-	  ELF-FDPIC binfmt's brk and stack allocator.
-
-	  Because of the obvious security issues, this option should only be
-	  enabled on embedded devices where you control what is run in
-	  userspace.  Since that isn't generally a problem on no-MMU systems,
-	  it is normally safe to say Y here.
-
-	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
-
 config SYSTEM_DATA_VERIFICATION
 	def_bool n
 	select SYSTEM_TRUSTED_KEYRING
diff --git a/lib/Kconfig.debug b/lib/Kconfig.debug
index 075cd25363ac..25763dcc7c4b 100644
--- a/lib/Kconfig.debug
+++ b/lib/Kconfig.debug
@@ -698,40 +698,6 @@ config DEBUG_OBJECTS_ENABLE_DEFAULT
 	help
 	  Debug objects boot parameter default value
 
-config DEBUG_SLAB
-	bool "Debug slab memory allocations"
-	depends on DEBUG_KERNEL && SLAB
-	help
-	  Say Y here to have the kernel do limited verification on memory
-	  allocation as well as poisoning memory on free to catch use of freed
-	  memory. This can make kmalloc/kfree-intensive workloads much slower.
-
-config SLUB_DEBUG_ON
-	bool "SLUB debugging on by default"
-	depends on SLUB && SLUB_DEBUG
-	default n
-	help
-	  Boot with debugging on by default. SLUB boots by default with
-	  the runtime debug capabilities switched off. Enabling this is
-	  equivalent to specifying the "slub_debug" parameter on boot.
-	  There is no support for more fine grained debug control like
-	  possible with slub_debug=xxx. SLUB debugging may be switched
-	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
-	  "slub_debug=-".
-
-config SLUB_STATS
-	default n
-	bool "Enable SLUB performance statistics"
-	depends on SLUB && SYSFS
-	help
-	  SLUB statistics are useful to debug SLUBs allocation behavior in
-	  order find ways to optimize the allocator. This should never be
-	  enabled for production use since keeping statistics slows down
-	  the allocator by a few percentage points. The slabinfo command
-	  supports the determination of the most active slabs to figure
-	  out which slabs are relevant to a particular load.
-	  Try running: slabinfo -DA
-
 config HAVE_DEBUG_KMEMLEAK
 	bool
 
diff --git a/mm/Kconfig b/mm/Kconfig
index 905c205e14f3..169e64192e48 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -270,6 +270,19 @@ config SLAB_FREELIST_HARDENED
 	  sanity-checking than others. This option is most effective with
 	  CONFIG_SLUB.
 
+config SLUB_STATS
+	default n
+	bool "Enable SLUB performance statistics"
+	depends on SLUB && SYSFS
+	help
+	  SLUB statistics are useful to debug SLUBs allocation behavior in
+	  order find ways to optimize the allocator. This should never be
+	  enabled for production use since keeping statistics slows down
+	  the allocator by a few percentage points. The slabinfo command
+	  supports the determination of the most active slabs to figure
+	  out which slabs are relevant to a particular load.
+	  Try running: slabinfo -DA
+
 config SLUB_CPU_PARTIAL
 	default y
 	depends on SLUB && SMP
@@ -307,6 +320,40 @@ config SHUFFLE_PAGE_ALLOCATOR
 
 	  Say Y if unsure.
 
+config COMPAT_BRK
+	bool "Disable heap randomization"
+	default y
+	help
+	  Randomizing heap placement makes heap exploits harder, but it
+	  also breaks ancient binaries (including anything libc5 based).
+	  This option changes the bootup default to heap randomization
+	  disabled, and can be overridden at runtime by setting
+	  /proc/sys/kernel/randomize_va_space to 2.
+
+	  On non-ancient distros (post-2000 ones) N is usually a safe choice.
+
+config MMAP_ALLOW_UNINITIALIZED
+	bool "Allow mmapped anonymous memory to be uninitialized"
+	depends on EXPERT && !MMU
+	default n
+	help
+	  Normally, and according to the Linux spec, anonymous memory obtained
+	  from mmap() has its contents cleared before it is passed to
+	  userspace.  Enabling this config option allows you to request that
+	  mmap() skip that if it is given an MAP_UNINITIALIZED flag, thus
+	  providing a huge performance boost.  If this option is not enabled,
+	  then the flag will be ignored.
+
+	  This is taken advantage of by uClibc's malloc(), and also by
+	  ELF-FDPIC binfmt's brk and stack allocator.
+
+	  Because of the obvious security issues, this option should only be
+	  enabled on embedded devices where you control what is run in
+	  userspace.  Since that isn't generally a problem on no-MMU systems,
+	  it is normally safe to say Y here.
+
+	  See Documentation/admin-guide/mm/nommu-mmap.rst for more information.
+
 config SELECT_MEMORY_MODEL
 	def_bool y
 	depends on ARCH_SELECT_MEMORY_MODEL
@@ -964,6 +1011,15 @@ config ARCH_USES_HIGH_VMA_FLAGS
 config ARCH_HAS_PKEYS
 	bool
 
+config VM_EVENT_COUNTERS
+	default y
+	bool "Enable VM event counters for /proc/vmstat" if EXPERT
+	help
+	  VM event counters are needed for event counts to be shown.
+	  This option allows the disabling of the VM event counters
+	  on EXPERT systems.  /proc/vmstat will only show page counts
+	  if VM event counters are disabled.
+
 config PERCPU_STATS
 	bool "Collect percpu memory statistics"
 	help
diff --git a/mm/Kconfig.debug b/mm/Kconfig.debug
index 5bd5bb097252..197eb287bf82 100644
--- a/mm/Kconfig.debug
+++ b/mm/Kconfig.debug
@@ -45,6 +45,37 @@ config DEBUG_PAGEALLOC_ENABLE_DEFAULT
 	  Enable debug page memory allocations by default? This value
 	  can be overridden by debug_pagealloc=off|on.
 
+config DEBUG_SLAB
+	bool "Debug slab memory allocations"
+	depends on DEBUG_KERNEL && SLAB
+	help
+	  Say Y here to have the kernel do limited verification on memory
+	  allocation as well as poisoning memory on free to catch use of freed
+	  memory. This can make kmalloc/kfree-intensive workloads much slower.
+
+config SLUB_DEBUG
+	default y
+	bool "Enable SLUB debugging support" if EXPERT
+	depends on SLUB && SYSFS
+	help
+	  SLUB has extensive debug support features. Disabling these can
+	  result in significant savings in code size. This also disables
+	  SLUB sysfs support. /sys/slab will not exist and there will be
+	  no support for cache validation etc.
+
+config SLUB_DEBUG_ON
+	bool "SLUB debugging on by default"
+	depends on SLUB && SLUB_DEBUG
+	default n
+	help
+	  Boot with debugging on by default. SLUB boots by default with
+	  the runtime debug capabilities switched off. Enabling this is
+	  equivalent to specifying the "slub_debug" parameter on boot.
+	  There is no support for more fine grained debug control like
+	  possible with slub_debug=xxx. SLUB debugging may be switched
+	  off in a kernel built with CONFIG_SLUB_DEBUG_ON by specifying
+	  "slub_debug=-".
+
 config PAGE_OWNER
 	bool "Track page owner"
 	depends on DEBUG_KERNEL && STACKTRACE_SUPPORT
-- 
2.36.1

Re: [PATCH] mm: Kconfig: reorganize misplaced mm options

[Johannes Weiner]

On Wed, May 25, 2022 at 01:25:59PM +0200, Vlastimil Babka wrote:
> After commits 7b42f1041c98 ("mm: Kconfig: move swap and slab config
> options to the MM section") and 519bcb797907 ("mm: Kconfig: group swap,
> slab, hotplug and thp options into submenus") we now have nicely
> organized mm related config options. I have noticed some that were still
> misplaced, so this moves them from various places into the new structure:
> 
> VM_EVENT_COUNTERS, COMPAT_BRK, MMAP_ALLOW_UNINITIALIZED to mm/Kconfig
> and general MM section.
> 
> SLUB_STATS to mm/Kconfig and the slab submenu.
> 
> DEBUG_SLAB, SLUB_DEBUG, SLUB_DEBUG_ON to mm/Kconfig.debug and the Kernel
> hacking / Memory Debugging submenu.
> 
> Signed-off-by: Vlastimil Babka <vbabka@suse.cz>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>