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    SubjectRe: [PATCH v2 0/3] mm: support huge vmalloc mapping on arm64/x86
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    Le 27/12/2021 à 15:59, Kefeng Wang a écrit :
    > Huge vmalloc mappings is supported on PPC[1], but this feature should
    > be not only used on PPC, it could be used on arch support HAVE_ARCH_HUGE_VMAP
    > and PMD sized vmap mappings. this patchset is to enable this feature
    > on arm64/x86.
    >
    > There are some disadvantages about this feature[2], one of the main

    There are some disadvantage, ok, so are there advantages as well ?

    > concerns is the possible memory fragmentation/waste in some scenarios,
    > also archs must ensure that any arch specific vmalloc allocations that
    > require PAGE_SIZE mappings(eg, module alloc with STRICT_MODULE_RWX)
    > use the VM_NO_HUGE_VMAP flag to inhibit larger mappings.
    >
    > Based on the above considerations, we add the first patch is to let
    > user to control huge vmalloc mapping default behavior. Meanwhile,
    > add new kernel parameter hugevmalloc=on/off to enable/disable this
    > feature at boot time, nohugevmalloc parameter is still supported.
    >
    > The later two patches to enable this feature on arm64/x86, select
    > HAVE_ARCH_HUGE_VMALLOC and mark VM_NO_HUGE_VMAP in arch's module_alloc().
    >
    > This patchset based on next-20211224.
    >
    > v2:
    > - Default y for HUGE_VMALLOC_DEFAULT_ENABLED, not only select it on PPC
    > - Fix copy/type error
    > - Mark VM_NO_HUGE_VMAP in module_alloc() on arm64/x86
    >
    > [1] https://lore.kernel.org/linux-mm/20210317062402.533919-1-npiggin@gmail.com/
    > [2] https://lore.kernel.org/linux-mm/1616036421.amjz2efujj.astroid@bobo.none/
    >
    > Kefeng Wang (3):
    > mm: vmalloc: Let user to control huge vmalloc default behavior
    > arm64: Support huge vmalloc mappings
    > x86: Support huge vmalloc mappings
    >
    > .../admin-guide/kernel-parameters.txt | 14 +++++++++++++-
    > arch/arm64/Kconfig | 1 +
    > arch/arm64/kernel/module.c | 5 +++--
    > arch/x86/Kconfig | 1 +
    > arch/x86/kernel/module.c | 4 ++--
    > mm/Kconfig | 8 ++++++++
    > mm/vmalloc.c | 18 +++++++++++++++++-
    > 7 files changed, 45 insertions(+), 6 deletions(-)
    >
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