diff options
| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2023-03-15 14:31:33 +0300 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-04-06 05:42:46 +0300 |
| commit | 23baf831a32c04f9a968812511540b1b3e648bf5 (patch) | |
| tree | fcaca52cefbef2707710ce057f58fb1c955a0559 /arch/arm64/Kconfig | |
| parent | 61883d3c32418f16e35e030ca0cfd5d2de95a649 (diff) | |
| download | linux-23baf831a32c04f9a968812511540b1b3e648bf5.tar.xz | |
mm, treewide: redefine MAX_ORDER sanely
MAX_ORDER currently defined as number of orders page allocator supports:
user can ask buddy allocator for page order between 0 and MAX_ORDER-1.
This definition is counter-intuitive and lead to number of bugs all over
the kernel.
Change the definition of MAX_ORDER to be inclusive: the range of orders
user can ask from buddy allocator is 0..MAX_ORDER now.
[kirill@shutemov.name: fix min() warning]
Link: https://lkml.kernel.org/r/20230315153800.32wib3n5rickolvh@box
[akpm@linux-foundation.org: fix another min_t warning]
[kirill@shutemov.name: fixups per Zi Yan]
Link: https://lkml.kernel.org/r/20230316232144.b7ic4cif4kjiabws@box.shutemov.name
[akpm@linux-foundation.org: fix underlining in docs]
Link: https://lore.kernel.org/oe-kbuild-all/202303191025.VRCTk6mP-lkp@intel.com/
Link: https://lkml.kernel.org/r/20230315113133.11326-11-kirill.shutemov@linux.intel.com
Signed-off-by: Kirill A. Shutemov <kirill.shutemov@linux.intel.com>
Reviewed-by: Michael Ellerman <mpe@ellerman.id.au> [powerpc]
Cc: "Kirill A. Shutemov" <kirill@shutemov.name>
Cc: Zi Yan <ziy@nvidia.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Diffstat (limited to 'arch/arm64/Kconfig')
| -rw-r--r-- | arch/arm64/Kconfig | 27 |
1 files changed, 12 insertions, 15 deletions
diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig index 1023e896d46b..cb5c6aa3254e 100644 --- a/arch/arm64/Kconfig +++ b/arch/arm64/Kconfig @@ -1476,22 +1476,22 @@ config XEN # include/linux/mmzone.h requires the following to be true: # -# MAX_ORDER - 1 + PAGE_SHIFT <= SECTION_SIZE_BITS +# MAX_ORDER + PAGE_SHIFT <= SECTION_SIZE_BITS # -# so the maximum value of MAX_ORDER is SECTION_SIZE_BITS + 1 - PAGE_SHIFT: +# so the maximum value of MAX_ORDER is SECTION_SIZE_BITS - PAGE_SHIFT: # # | SECTION_SIZE_BITS | PAGE_SHIFT | max MAX_ORDER | default MAX_ORDER | # ----+-------------------+--------------+-----------------+--------------------+ -# 4K | 27 | 12 | 16 | 11 | -# 16K | 27 | 14 | 14 | 12 | -# 64K | 29 | 16 | 14 | 14 | +# 4K | 27 | 12 | 15 | 10 | +# 16K | 27 | 14 | 13 | 11 | +# 64K | 29 | 16 | 13 | 13 | config ARCH_FORCE_MAX_ORDER int "Maximum zone order" if ARM64_4K_PAGES || ARM64_16K_PAGES - default "14" if ARM64_64K_PAGES - range 12 14 if ARM64_16K_PAGES - default "12" if ARM64_16K_PAGES - range 11 16 if ARM64_4K_PAGES - default "11" + default "13" if ARM64_64K_PAGES + range 11 13 if ARM64_16K_PAGES + default "11" if ARM64_16K_PAGES + range 10 15 if ARM64_4K_PAGES + default "10" help The kernel memory allocator divides physically contiguous memory blocks into "zones", where each zone is a power of two number of @@ -1500,14 +1500,11 @@ config ARCH_FORCE_MAX_ORDER blocks of physically contiguous memory, then you may need to increase this value. - This config option is actually maximum order plus one. For example, - a value of 11 means that the largest free memory block is 2^10 pages. - We make sure that we can allocate up to a HugePage size for each configuration. Hence we have : - MAX_ORDER = (PMD_SHIFT - PAGE_SHIFT) + 1 => PAGE_SHIFT - 2 + MAX_ORDER = PMD_SHIFT - PAGE_SHIFT => PAGE_SHIFT - 3 - However for 4K, we choose a higher default value, 11 as opposed to 10, giving us + However for 4K, we choose a higher default value, 10 as opposed to 9, giving us 4M allocations matching the default size used by generic code. config UNMAP_KERNEL_AT_EL0 |