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

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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: Alexei Starovoitov <ast@kernel.org>
Link: https://lore.kernel.org/r/20250222024427.30294-7-alexei.starovoitov@gmail.com
Signed-off-by: Alexei Starovoitov <ast@kernel.org>
This commit is contained in:
Alexei Starovoitov 2025-02-21 18:44:27 -08:00
parent e8d78dbd01
commit c9eb8102e2
3 changed files with 23 additions and 7 deletions
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2
include/linux/bpf.h
View File

@ -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,

5
kernel/bpf/arena.c
View File

@ -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;

23
kernel/bpf/syscall.c
View File

@ -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;
}