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@xxxxxxxxx/ > [2] https://lore.kernel.org/linux-mm/1616036421.amjz2efujj.astroid@xxxxxxxxx/ > > 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(-) >
