Hi Eric,
> On Feb 9, 2022, at 5:13 PM, Eric Dumazet <eric.dumazet@xxxxxxxxx> wrote:
>
>
> On 2/8/22 14:05, Song Liu wrote:
>> Fix build with CONFIG_TRANSPARENT_HUGEPAGE=n with BPF_PROG_PACK_SIZE as
>> PAGE_SIZE.
>>
>> Fixes: 57631054fae6 ("bpf: Introduce bpf_prog_pack allocator")
>> Reported-by: kernel test robot <lkp@xxxxxxxxx>
>> Signed-off-by: Song Liu <song@xxxxxxxxxx>
>> ---
>> kernel/bpf/core.c | 4 ++++
>> 1 file changed, 4 insertions(+)
>>
>> diff --git a/kernel/bpf/core.c b/kernel/bpf/core.c
>> index 306aa63fa58e..9519264ab1ee 100644
>> --- a/kernel/bpf/core.c
>> +++ b/kernel/bpf/core.c
>> @@ -814,7 +814,11 @@ int bpf_jit_add_poke_descriptor(struct bpf_prog *prog,
>> * allocator. The prog_pack allocator uses HPAGE_PMD_SIZE page (2MB on x86)
>> * to host BPF programs.
>> */
>> +#ifdef CONFIG_TRANSPARENT_HUGEPAGE
>> #define BPF_PROG_PACK_SIZE HPAGE_PMD_SIZE
>> +#else
>> +#define BPF_PROG_PACK_SIZE PAGE_SIZE
>> +#endif
>> #define BPF_PROG_CHUNK_SHIFT 6
>> #define BPF_PROG_CHUNK_SIZE (1 << BPF_PROG_CHUNK_SHIFT)
>> #define BPF_PROG_CHUNK_MASK (~(BPF_PROG_CHUNK_SIZE - 1))
>
> BTW, I do not understand with module_alloc(HPAGE_PMD_SIZE) would necessarily allocate a huge page.
>
> I am pretty sure it does not on x86_64 and dual socket host (NUMA)
>
> It seems you need to multiply this by num_online_nodes() or change the way __vmalloc_node_range()
>
> works, because it currently does:
>
> if (vmap_allow_huge && !(vm_flags & VM_NO_HUGE_VMAP)) {
> unsigned long size_per_node;
>
> /*
> * Try huge pages. Only try for PAGE_KERNEL allocations,
> * others like modules don't yet expect huge pages in
> * their allocations due to apply_to_page_range not
> * supporting them.
> */
>
> size_per_node = size;
> if (node == NUMA_NO_NODE)
> <*> size_per_node /= num_online_nodes();
> if (arch_vmap_pmd_supported(prot) && size_per_node >= PMD_SIZE)
> shift = PMD_SHIFT;
> else
> shift = arch_vmap_pte_supported_shift(size_per_node);
Thanks for highlighting this issue! I will address this in a follow up commit.
Regards,
Song
