Commit 0710d012 authored by Vlastimil Babka's avatar Vlastimil Babka Committed by Andrew Morton
Browse files

mm: Kconfig: reorganize misplaced mm options 

After commits 7b42f104 ("mm: Kconfig: move swap and slab config
options to the MM section") and 519bcb79 ("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.

Link: https://lkml.kernel.org/r/20220525112559.1139-1-vbabka@suse.cz


Signed-off-by: default avatarVlastimil Babka <vbabka@suse.cz>
Acked-by: default avatarJohannes Weiner <hannes@cmpxchg.org>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
parent fbf4df06

init/Kconfig

+0 −53
Original line number Diff line number Diff line
@@ -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

lib/Kconfig.debug

+0 −34
Original line number Diff line number Diff line
@@ -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

mm/Kconfig

+56 −0
Original line number Diff line number Diff line
@@ -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

mm/Kconfig.debug

+31 −0
Original line number Diff line number Diff line
@@ -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