lkml.org 
[lkml]   [2022]   [Jul]   [1]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
/
Date
From
SubjectRe: [PATCH v5 bpf-next 1/5] module: introduce module_alloc_huge
On Fri, Jun 24, 2022 at 02:57:08PM -0700, Song Liu wrote:
> Introduce module_alloc_huge, which allocates huge page backed memory in
> module memory space. The primary user of this memory is bpf_prog_pack
> (multiple BPF programs sharing a huge page).
>
> Signed-off-by: Song Liu <song@kernel.org>

I see mm not Cc'd. I'd like review from them.

> ---
> arch/x86/kernel/module.c | 21 +++++++++++++++++++++
> include/linux/moduleloader.h | 5 +++++
> kernel/module/main.c | 8 ++++++++
> 3 files changed, 34 insertions(+)
>
> diff --git a/arch/x86/kernel/module.c b/arch/x86/kernel/module.c
> index b98ffcf4d250..63f6a16c70dc 100644
> --- a/arch/x86/kernel/module.c
> +++ b/arch/x86/kernel/module.c
> @@ -86,6 +86,27 @@ void *module_alloc(unsigned long size)
> return p;
> }
>
> +void *module_alloc_huge(unsigned long size)
> +{
> + gfp_t gfp_mask = GFP_KERNEL;
> + void *p;
> +
> + if (PAGE_ALIGN(size) > MODULES_LEN)
> + return NULL;
> +
> + p = __vmalloc_node_range(size, MODULE_ALIGN,
> + MODULES_VADDR + get_module_load_offset(),
> + MODULES_END, gfp_mask, PAGE_KERNEL,
> + VM_DEFER_KMEMLEAK | VM_ALLOW_HUGE_VMAP,
> + NUMA_NO_NODE, __builtin_return_address(0));
> + if (p && (kasan_alloc_module_shadow(p, size, gfp_mask) < 0)) {
> + vfree(p);
> + return NULL;
> + }
> +
> + return p;
> +}

1) When things like kernel/bpf/core.c start using a module alloc it
is time to consider genearlizing this.

2) How we free is important, and each arch does something funky for
this. This is not addressed here.

And yes I welcome generalizing generic module_alloc() too as suggested
before. The concern on my part is the sloppiness this enables.

Luis

> +
> #ifdef CONFIG_X86_32
> int apply_relocate(Elf32_Shdr *sechdrs,
> const char *strtab,
> diff --git a/include/linux/moduleloader.h b/include/linux/moduleloader.h
> index 9e09d11ffe5b..d34743a88938 100644
> --- a/include/linux/moduleloader.h
> +++ b/include/linux/moduleloader.h
> @@ -26,6 +26,11 @@ unsigned int arch_mod_section_prepend(struct module *mod, unsigned int section);
> sections. Returns NULL on failure. */
> void *module_alloc(unsigned long size);
>
> +/* Allocator used for allocating memory in module memory space. If size is
> + * greater than PMD_SIZE, allow using huge pages. Returns NULL on failure.
> + */
> +void *module_alloc_huge(unsigned long size);
> +
> /* Free memory returned from module_alloc. */
> void module_memfree(void *module_region);
>
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index fed58d30725d..349b2a8bd20f 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -1613,6 +1613,14 @@ void * __weak module_alloc(unsigned long size)
> NUMA_NO_NODE, __builtin_return_address(0));
> }
>
> +void * __weak module_alloc_huge(unsigned long size)
> +{
> + return __vmalloc_node_range(size, 1, VMALLOC_START, VMALLOC_END,
> + GFP_KERNEL, PAGE_KERNEL_EXEC,
> + VM_FLUSH_RESET_PERMS | VM_ALLOW_HUGE_VMAP,
> + NUMA_NO_NODE, __builtin_return_address(0));
> +}
> +
> bool __weak module_init_section(const char *name)
> {
> return strstarts(name, ".init");
> --
> 2.30.2
>

\
 
 \ /
  Last update: 2022-07-02 01:21    [W:0.104 / U:1.204 seconds]
©2003-2020 Jasper Spaans|hosted at Digital Ocean and TransIP|Read the blog|Advertise on this site