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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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