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Date: Fri, 1 Jul 2022 16:20:55 -0700 From: Luis Chamberlain <mcgrof@...nel.org> To: Song Liu <song@...nel.org> Cc: linux-kernel@...r.kernel.org, netdev@...r.kernel.org, x86@...r.kernel.org, dave.hansen@...ux.intel.com, rick.p.edgecombe@...el.com, kernel-team@...com, daniel@...earbox.net Subject: Re: [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@...nel.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 >
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