Re: [PATCH v5 03/12] mm/sparse-vmemmap: introduce CONFIG_VMEMMAP_OPTIMIZATION
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From: "David Hildenbrand (Arm)" <david@kernel.org>
Date: 2026-09-29 07:11:19
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On 9/27/26 04:54, Muchun Song wrote:
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The section-based vmemmap optimization infrastructure is guarded by CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP, but it can also be used by ZONE_DEVICE users that set dev_pagemap::vmemmap_shift. Introduce CONFIG_VMEMMAP_OPTIMIZATION as a common config for the shared infrastructure. Select the new option from HUGETLB_PAGE_OPTIMIZE_VMEMMAP and from ZONE_DEVICE when the architecture opts in to DAX vmemmap optimization, and use it to guard the generic sparse-vmemmap state and helpers. Signed-off-by: Muchun Song <redacted> Acked-by: Qi Zheng <qi.zheng@linux.dev> Acked-by: Mike Rapoport (Microsoft) <rppt@kernel.org> --- v5: - Move this patch after the shared tail-page factoring. - Select VMEMMAP_OPTIMIZATION from ZONE_DEVICE instead of DEV_DAX, covering all users of dev_pagemap::vmemmap_shift, reported by Sashiko. v4: - Rename SPARSEMEM_VMEMMAP_OPTIMIZATION to VMEMMAP_OPTIMIZATION (suggested by Mike Rapoport) - Collect Acked-by from Mike Rapoport v2: - Fix SPARSEMEM_VMEMMAP_OPTIMIZATION being selected without SPARSEMEM_VMEMMAP reported by Sashiko. - Add an explicit DEV_DAX dependency on ZONE_DEVICE - Collect Acked-by from Qi Zheng --- arch/x86/entry/vdso/vdso32/fake_32bit_build.h | 2 +- fs/Kconfig | 1 + include/linux/mm.h | 3 +++ include/linux/mmzone.h | 10 +++++----- include/linux/page-flags.h | 5 ++--- mm/Kconfig | 5 +++++ mm/sparse-vmemmap.c | 2 +- mm/sparse.h | 6 +++--- 8 files changed, 21 insertions(+), 13 deletions(-)diff --git a/arch/x86/entry/vdso/vdso32/fake_32bit_build.h b/arch/x86/entry/vdso/vdso32/fake_32bit_build.h index bc3e549795c3..72a92cb9b53d 100644 --- a/arch/x86/entry/vdso/vdso32/fake_32bit_build.h +++ b/arch/x86/entry/vdso/vdso32/fake_32bit_build.h@@ -11,7 +11,7 @@ #undef CONFIG_PGTABLE_LEVELS #undef CONFIG_ILLEGAL_POINTER_VALUE #undef CONFIG_SPARSEMEM_VMEMMAP -#undef CONFIG_HUGETLB_PAGE_OPTIMIZE_VMEMMAP +#undef CONFIG_VMEMMAP_OPTIMIZATION #undef CONFIG_NR_CPUS #undef CONFIG_PARAVIRT_XXLdiff --git a/fs/Kconfig b/fs/Kconfig index d1c210c6508f..1454b7fe9641 100644 --- a/fs/Kconfig +++ b/fs/Kconfig@@ -278,6 +278,7 @@ config HUGETLB_PAGE_OPTIMIZE_VMEMMAP def_bool HUGETLB_PAGE depends on ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP depends on SPARSEMEM_VMEMMAP + select VMEMMAP_OPTIMIZATION
Acked-by: David Hildenbrand (Arm) <david@kernel.org> Is there a path to remove HUGETLB_PAGE_OPTIMIZE_VMEMMAP, and to merge ARCH_WANT_OPTIMIZE_DAX_VMEMMAP+ARCH_WANT_OPTIMIZE_HUGETLB_VMEMMAP into a ARCH_SUPPORTS_VMEMMAP_OPTIMIZATION? -- Cheers, David