[RFC PATCH 0/8] Unify hugetlb into arch_get_unmapped_area functions

Oscar Salvador
2024-07-10T10:51:28Z

Hi all,

this is a first attempt to get rid of a fair amount of duplicated code
wrt. hugetlb and *get_unmapped_area* functions.

HugeTLB registers a .get_unmapped_area function which gets called from
__get_unmapped_area().
hugetlb_get_unmapped_area() is defined by a bunch of architectures and
it also has a generic definition for those that do not define it.
Short-long story is that there is a ton of duplicated code between
specific hugetlb *_get_unmapped_area_* functions and mm-core functions,
so we can do better by teaching arch_get_unmapped_area* functions how
to deal with hugetlb mappings.

Note that not a lot of things need to be taught though.
hugetlb_mmap_check_and_align(), that gets called for hugetlb mappings
prior to call mm_get_unmapped_area_vmflags(), runs some sanity checks
and aligns the addr to huge_page_size(), so we do not need to that
down the road in the respective {generic,arch}_get_unmapped_area*
functions.

More information can be found in the respective patches.

LTP mmapstress and hugemmap testcases were ran on arm64, powerpc64le and
x86_64 without raising any issue.

Oscar Salvador (8):
mm/mmap: Teach generic_get_unmapped_area{_topdown} to handle hugetlb
mappings
arch/s390: Teach arch_get_unmapped_area{_topdown} to handle hugetlb
mappings
arch/x86: Teach arch_get_unmapped_area_vmflags to handle hugetlb
mappings
arch/sparc: Teach arch_get_unmapped_area{_topdown} to handle hugetlb
mappings
arch/powerpc: Teach book3s64 arch_get_unmapped_area{_topdown} to
handle hugetlb mappings
mm: Make hugetlb mappings go through mm_get_unmapped_area_vmflags
mm: Drop hugetlb_get_unmapped_area{_*} functions
mm: Consolidate common checks in hugetlb_mmap_check_and_align

arch/loongarch/include/asm/hugetlb.h | 4 -
arch/mips/include/asm/hugetlb.h | 4 -
arch/parisc/include/asm/hugetlb.h | 15 ----
arch/parisc/mm/hugetlbpage.c | 23 ------
arch/powerpc/mm/book3s64/slice.c | 49 +++++++-----
arch/s390/include/asm/hugetlb.h | 16 ----
arch/s390/mm/hugetlbpage.c | 84 ---------------------
arch/s390/mm/mmap.c | 8 +-
arch/sh/include/asm/hugetlb.h | 15 ----
arch/sparc/kernel/sys_sparc_32.c | 16 +++-
arch/sparc/kernel/sys_sparc_64.c | 36 +++++++--
arch/sparc/mm/hugetlbpage.c | 108 ---------------------------
arch/x86/kernel/sys_x86_64.c | 24 ++++--
arch/x86/mm/hugetlbpage.c | 100 -------------------------
fs/hugetlbfs/inode.c | 92 ++---------------------
include/asm-generic/hugetlb.h | 7 --
include/linux/hugetlb.h | 21 +++---
mm/mmap.c | 19 ++++-
18 files changed, 129 insertions(+), 512 deletions(-)

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2.45.2