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authorVlastimil Babka <vbabka@suse.cz>2022-05-25 14:25:59 +0300
committerakpm <akpm@linux-foundation.org>2022-05-27 19:33:47 +0300
commit0710d0122abc93adcb9a70a78f1625c491f6ad91 (patch)
tree1ee56844a3b8b90d8b0411d6c56440d3e5b62bf4 /mm/Kconfig
parentfbf4df0699926cf620b2f722ddc213826e248962 (diff)
downloadlinux-0710d0122abc93adcb9a70a78f1625c491f6ad91.tar.xz
mm: Kconfig: reorganize misplaced mm options
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. Link: https://lkml.kernel.org/r/20220525112559.1139-1-vbabka@suse.cz Signed-off-by: Vlastimil Babka <vbabka@suse.cz> Acked-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'mm/Kconfig')
-rw-r--r--mm/Kconfig56
1 files changed, 56 insertions, 0 deletions
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