Re: [PATCH v2 3/3] x86: Support huge vmalloc mappings

[Christophe Leroy <christophe.leroy@csgroup.eu>]

Le 27/12/2021 à 15:59, Kefeng Wang a écrit :
> This patch select HAVE_ARCH_HUGE_VMALLOC to let X86_64 and X86_PAE
> support huge vmalloc mappings.
> 
> Cc: Thomas Gleixner <tglx@linutronix.de>
> Cc: Ingo Molnar <mingo@redhat.com>
> Cc: Borislav Petkov <bp@alien8.de>
> Cc: Dave Hansen <dave.hansen@linux.intel.com>
> Cc: "H. Peter Anvin" <hpa@zytor.com>
> Signed-off-by: Kefeng Wang <wangkefeng.wang@huawei.com>
> ---
>   Documentation/admin-guide/kernel-parameters.txt | 4 ++--
>   arch/x86/Kconfig                                | 1 +
>   arch/x86/kernel/module.c                        | 4 ++--
>   3 files changed, 5 insertions(+), 4 deletions(-)
> 
> diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
> index e3f9fd7ec106..ffce6591ae64 100644
> --- a/Documentation/admin-guide/kernel-parameters.txt
> +++ b/Documentation/admin-guide/kernel-parameters.txt
> @@ -1639,7 +1639,7 @@
>   			precedence over memory_hotplug.memmap_on_memory.
>   
>   
> -	hugevmalloc=	[KNL,PPC,ARM64] Reguires CONFIG_HAVE_ARCH_HUGE_VMALLOC
> +	hugevmalloc=	[KNL,PPC,ARM64,X86] Reguires CONFIG_HAVE_ARCH_HUGE_VMALLOC
>   			Format: { on | off }
>   			Default set by CONFIG_HUGE_VMALLOC_DEFAULT_ENABLED.
>   
> @@ -3424,7 +3424,7 @@
>   
>   	nohugeiomap	[KNL,X86,PPC,ARM64] Disable kernel huge I/O mappings.
>   
> -	nohugevmalloc	[KNL,PPC,ARM64] Disable kernel huge vmalloc mappings.
> +	nohugevmalloc	[KNL,PPC,ARM64,X86] Disable kernel huge vmalloc mappings.
>   
>   	nosmt		[KNL,S390] Disable symmetric multithreading (SMT).
>   			Equivalent to smt=1.
> diff --git a/arch/x86/Kconfig b/arch/x86/Kconfig
> index ebe8fc76949a..f6bf6675bbe7 100644
> --- a/arch/x86/Kconfig
> +++ b/arch/x86/Kconfig
> @@ -157,6 +157,7 @@ config X86
>   	select HAVE_ACPI_APEI_NMI		if ACPI
>   	select HAVE_ALIGNED_STRUCT_PAGE		if SLUB
>   	select HAVE_ARCH_AUDITSYSCALL
> +	select HAVE_ARCH_HUGE_VMALLOC		if HAVE_ARCH_HUGE_VMAP
>   	select HAVE_ARCH_HUGE_VMAP		if X86_64 || X86_PAE
>   	select HAVE_ARCH_JUMP_LABEL
>   	select HAVE_ARCH_JUMP_LABEL_RELATIVE
> diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
> index 95fa745e310a..6bf5cb7d876a 100644
> --- a/arch/x86/kernel/module.c
> +++ b/arch/x86/kernel/module.c
> @@ -75,8 +75,8 @@ void *module_alloc(unsigned long size)
>   
>   	p = __vmalloc_node_range(size, MODULE_ALIGN,
>   				    MODULES_VADDR + get_module_load_offset(),
> -				    MODULES_END, gfp_mask,
> -				    PAGE_KERNEL, VM_DEFER_KMEMLEAK, NUMA_NO_NODE,
> +				    MODULES_END, gfp_mask, PAGE_KERNEL,
> +				    VM_DEFER_KMEMLEAK | VM_NO_HUGE_VMAP, NUMA_NO_NODE,

you should add a comment like powerpc (commit 8abddd968a30 
("powerpc/64s/radix: Enable huge vmalloc mappings")) to explain why this 
requires VM_NO_HUGE_VMAP

>   				    __builtin_return_address(0));
>   	if (p && (kasan_module_alloc(p, size, gfp_mask) < 0)) {
>   		vfree(p);