Re: [PATCH v3 bpf RESEND 3/4] module: introduce module_alloc_huge

[Song Liu <songliubraving@fb.com>]

> On Apr 14, 2022, at 11:32 PM, Christoph Hellwig <hch@infradead.org> wrote:
> 
> On Thu, Apr 14, 2022 at 12:59:13PM -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>
>> ---
>> arch/x86/kernel/module.c | 21 +++++++++++++++++++++
>> include/linux/moduleloader.h | 5 +++++
>> kernel/module.c | 5 +++++
>> 3 files changed, 31 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;
>> +}
>> +
>> #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.c b/kernel/module.c
>> index 6cea788fd965..b2c6cb682a7d 100644
>> --- a/kernel/module.c
>> +++ b/kernel/module.c
>> @@ -2839,6 +2839,11 @@ void * __weak module_alloc(unsigned long size)
>> 			NUMA_NO_NODE, __builtin_return_address(0));
>> }
>> 
>> +void * __weak module_alloc_huge(unsigned long size)
>> +{
>> +	return vmalloc_huge(size);
>> +}
> 
> Umm. This should use the same parameters as module_alloc except for
> also passing the new huge page flag.

Will fix the set and send v4. 

Thanks,
Song