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authorKirill A. Shutemov <kirill.shutemov@linux.intel.com>2023-03-15 14:31:33 +0300
committerAndrew Morton <akpm@linux-foundation.org>2023-04-06 05:42:46 +0300
commit23baf831a32c04f9a968812511540b1b3e648bf5 (patch)
treefcaca52cefbef2707710ce057f58fb1c955a0559 /mm/Kconfig
parent61883d3c32418f16e35e030ca0cfd5d2de95a649 (diff)
downloadlinux-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 'mm/Kconfig')
-rw-r--r--mm/Kconfig10
1 files changed, 5 insertions, 5 deletions
diff --git a/mm/Kconfig b/mm/Kconfig
index ca98b2072df5..969286ab14a1 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -346,9 +346,9 @@ config SHUFFLE_PAGE_ALLOCATOR
the presence of a memory-side-cache. There are also incidental
security benefits as it reduces the predictability of page
allocations to compliment SLAB_FREELIST_RANDOM, but the
- default granularity of shuffling on the "MAX_ORDER - 1" i.e,
- 10th order of pages is selected based on cache utilization
- benefits on x86.
+ default granularity of shuffling on the MAX_ORDER i.e, 10th
+ order of pages is selected based on cache utilization benefits
+ on x86.
While the randomization improves cache utilization it may
negatively impact workloads on platforms without a cache. For
@@ -666,8 +666,8 @@ config HUGETLB_PAGE_SIZE_VARIABLE
HUGETLB_PAGE_ORDER when there are multiple HugeTLB page sizes available
on a platform.
- Note that the pageblock_order cannot exceed MAX_ORDER - 1 and will be
- clamped down to MAX_ORDER - 1.
+ Note that the pageblock_order cannot exceed MAX_ORDER and will be
+ clamped down to MAX_ORDER.
config CONTIG_ALLOC
def_bool (MEMORY_ISOLATION && COMPACTION) || CMA