@@ -333,9 +333,9 @@ config ARCH_MMAP_RND_BITS_MAX
default 24 if ARM64_VA_BITS=39
default 27 if ARM64_VA_BITS=42
default 30 if ARM64_VA_BITS=47
- default 29 if ARM64_VA_BITS=48 && ARM64_64K_PAGES
- default 31 if ARM64_VA_BITS=48 && ARM64_16K_PAGES
- default 33 if ARM64_VA_BITS=48
+ default 29 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52) && ARM64_64K_PAGES
+ default 31 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52) && ARM64_16K_PAGES
+ default 33 if (ARM64_VA_BITS=48 || ARM64_VA_BITS=52)
default 14 if ARM64_64K_PAGES
default 16 if ARM64_16K_PAGES
default 18
When the 52-bit virtual addressing was introduced the select like ARCH_MMAP_RND_BITS_MAX logic was never updated to account for it. Because of that the rnd max bits knob is set to the default value of 18 when ARM64_VA_BITS=52. Fix this by setting ARCH_MMAP_RND_BITS_MAX to the same value that would be used if 48-bit addressing was used. Higher values can't used here because 52-bit addressing is used only if the caller provides a hint to mmap, with a fallback to 48-bit. The knob in question is an upper bound for what the user can set in /proc/sys/vm/mmap_rnd_bits, which in turn is used to determine how many random bits can be inserted into the base address used for mmap allocations. Since 48-bit allocations are legal with ARM64_VA_BITS=52, we need to make sure that the base address is small enough to facilitate this. Fixes: b6d00d47e81a ("arm64: mm: Introduce 52-bit Kernel VAs") Signed-off-by: Kornel Dulęba <korneld@google.com> Reviewed-by: Anshuman Khandual <anshuman.khandual@arm.com> --- v2: - Update commit message to explain why we need to set the same value as in the 48-bit case. arch/arm64/Kconfig | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-)