Le 11/04/2024 à 18:05, Mike Rapoport a écrit :
> From: "Mike Rapoport (IBM)" <rppt@xxxxxxxxxx>
>
> vmalloc allocations with VM_ALLOW_HUGE_VMAP that do not explictly
> specify node ID will use huge pages only if size_per_node is larger than
> PMD_SIZE.
> Still the actual allocated memory is not distributed between nodes and
> there is no advantage in such approach.
> On the contrary, BPF allocates PMD_SIZE * num_possible_nodes() for each
> new bpf_prog_pack, while it could do with PMD_SIZE'ed packs.
>
> Don't account for number of nodes for VM_ALLOW_HUGE_VMAP with
> NUMA_NO_NODE and use huge pages whenever the requested allocation size
> is larger than PMD_SIZE.
Patch looks ok but message is confusing. We also use huge pages at PTE
size, for instance 512k pages or 16k pages on powerpc 8xx, while
PMD_SIZE is 4M.
Christophe
>
> Signed-off-by: Mike Rapoport (IBM) <rppt@xxxxxxxxxx>
> ---
> mm/vmalloc.c | 9 ++-------
> 1 file changed, 2 insertions(+), 7 deletions(-)
>
> diff --git a/mm/vmalloc.c b/mm/vmalloc.c
> index 22aa63f4ef63..5fc8b514e457 100644
> --- a/mm/vmalloc.c
> +++ b/mm/vmalloc.c
> @@ -3737,8 +3737,6 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
> }
>
> if (vmap_allow_huge && (vm_flags & VM_ALLOW_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
> @@ -3746,13 +3744,10 @@ void *__vmalloc_node_range(unsigned long size, unsigned long align,
> * 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)
> + if (arch_vmap_pmd_supported(prot) && size >= PMD_SIZE)
> shift = PMD_SHIFT;
> else
> - shift = arch_vmap_pte_supported_shift(size_per_node);
> + shift = arch_vmap_pte_supported_shift(size);
>
> align = max(real_align, 1UL << shift);
> size = ALIGN(real_size, 1UL << shift);
