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| author | Kirill A. Shutemov <kirill.shutemov@linux.intel.com> | 2023-03-15 12:31:33 +0100 |
|---|---|---|
| committer | Andrew Morton <akpm@linux-foundation.org> | 2023-04-06 04:42:46 +0200 |
| commit | 23baf831a32c04f9a968812511540b1b3e648bf5 (patch) | |
| tree | fcaca52cefbef2707710ce057f58fb1c955a0559 /mm/Kconfig | |
| parent | iommu: fix MAX_ORDER usage in __iommu_dma_alloc_pages() (diff) | |
| download | linux-23baf831a32c04f9a968812511540b1b3e648bf5.tar.xz linux-23baf831a32c04f9a968812511540b1b3e648bf5.zip | |
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/Kconfig | 10 |
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 |