Commit c9eb8102 authored by Alexei Starovoitov's avatar Alexei Starovoitov
Browse files

bpf: Use try_alloc_pages() to allocate pages for bpf needs. 



Use try_alloc_pages() and free_pages_nolock() for BPF needs
when context doesn't allow using normal alloc_pages.
This is a prerequisite for further work.

Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20250222024427.30294-7-alexei.starovoitov@gmail.com


Signed-off-by: default avatarAlexei Starovoitov <ast@kernel.org>
parent e8d78dbd

include/linux/bpf.h

+1 −1
Original line number Diff line number Diff line
@@ -2348,7 +2348,7 @@ int generic_map_delete_batch(struct bpf_map *map, 
struct bpf_map *bpf_map_get_curr_or_next(u32 *id);

struct bpf_prog *bpf_prog_get_curr_or_next(u32 *id);



int bpf_map_alloc_pages(const struct bpf_map *map, gfp_t gfp, int nid,

int bpf_map_alloc_pages(const struct bpf_map *map, int nid,

			unsigned long nr_pages, struct page **page_array);

#ifdef CONFIG_MEMCG

void *bpf_map_kmalloc_node(const struct bpf_map *map, size_t size, gfp_t flags,

kernel/bpf/arena.c

+2 −3
Original line number Diff line number Diff line
@@ -287,7 +287,7 @@ static vm_fault_t arena_vm_fault(struct vm_fault *vmf) 
		return VM_FAULT_SIGSEGV;



	/* Account into memcg of the process that created bpf_arena */

	ret = bpf_map_alloc_pages(map, GFP_KERNEL | __GFP_ZERO, NUMA_NO_NODE, 1, &page);

	ret = bpf_map_alloc_pages(map, NUMA_NO_NODE, 1, &page);

	if (ret) {

		range_tree_set(&arena->rt, vmf->pgoff, 1);

		return VM_FAULT_SIGSEGV;
@@ -465,8 +465,7 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt 
	if (ret)

		goto out_free_pages;



	ret = bpf_map_alloc_pages(&arena->map, GFP_KERNEL | __GFP_ZERO,

				  node_id, page_cnt, pages);

	ret = bpf_map_alloc_pages(&arena->map, node_id, page_cnt, pages);

	if (ret)

		goto out;

kernel/bpf/syscall.c

+20 −3
Original line number Diff line number Diff line
@@ -569,7 +569,24 @@ static void bpf_map_release_memcg(struct bpf_map *map) 
}

#endif



int bpf_map_alloc_pages(const struct bpf_map *map, gfp_t gfp, int nid,

static bool can_alloc_pages(void)

{

	return preempt_count() == 0 && !irqs_disabled() &&

		!IS_ENABLED(CONFIG_PREEMPT_RT);

}



static struct page *__bpf_alloc_page(int nid)

{

	if (!can_alloc_pages())

		return try_alloc_pages(nid, 0);



	return alloc_pages_node(nid,

				GFP_KERNEL | __GFP_ZERO | __GFP_ACCOUNT

				| __GFP_NOWARN,

				0);

}



int bpf_map_alloc_pages(const struct bpf_map *map, int nid,

			unsigned long nr_pages, struct page **pages)

{

	unsigned long i, j;
@@ -582,14 +599,14 @@ int bpf_map_alloc_pages(const struct bpf_map *map, gfp_t gfp, int nid, 
	old_memcg = set_active_memcg(memcg);

#endif

	for (i = 0; i < nr_pages; i++) {

		pg = alloc_pages_node(nid, gfp | __GFP_ACCOUNT, 0);

		pg = __bpf_alloc_page(nid);



		if (pg) {

			pages[i] = pg;

			continue;

		}

		for (j = 0; j < i; j++)

			__free_page(pages[j]);

			free_pages_nolock(pages[j], 0);

		ret = -ENOMEM;

		break;

	}