Diffstat (limited to 'mm/Kconfig')
1 files changed, 19 insertions, 0 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index c2b57d81e15..71830ba7b98 100644
@@ -226,6 +226,25 @@ config HAVE_MLOCKED_PAGE_BIT
+ int "Low address space to protect from user allocation"
+ default 4096
+ This is the portion of low virtual memory which should be protected
+ from userspace allocation. Keeping a user from writing to low pages
+ can help reduce the impact of kernel NULL pointer bugs.
+ For most ia64, ppc64 and x86 users with lots of address space
+ a value of 65536 is reasonable and should cause no problems.
+ On arm and other archs it should not be higher than 32768.
+ Programs which use vm86 functionality would either need additional
+ permissions from either the LSM or the capabilities module or have
+ this protection disabled.
+ This value can be changed after boot using the
+ /proc/sys/vm/mmap_min_addr tunable.
int "Turn on mmap() excess space trimming before booting"
depends on !MMU