arena is the only map type whose map_mem_usage() still returns 0, so "bpftool map show" and fdinfo always showed 0 memlock for an arena no matter how many pages it had.
Count the pages that are actually mapped into the arena: bump a counter in apply_range_set_cb() when a page goes in and drop it in apply_range_clear_cb() when a page goes out, both under the arena spinlock. map_mem_usage() then just returns nr_pages << PAGE_SHIFT. Only real data pages are counted, not the scratch page. Signed-off-by: Jiayuan Chen <[email protected]> --- kernel/bpf/arena.c | 27 ++++++++++++++++----------- 1 file changed, 16 insertions(+), 11 deletions(-) diff --git a/kernel/bpf/arena.c b/kernel/bpf/arena.c index 80b7b8a69446..bc3460211604 100644 --- a/kernel/bpf/arena.c +++ b/kernel/bpf/arena.c @@ -55,8 +55,10 @@ struct bpf_arena { struct vm_struct *kern_vm; struct page *scratch_page; struct range_tree rt; - /* protects rt */ + /* protects rt and nr_pages */ rqspinlock_t spinlock; + /* number of pages currently populated in the arena */ + u64 nr_pages; struct list_head vma_list; /* protects vma_list */ struct mutex lock; @@ -143,14 +145,14 @@ static long compute_pgoff(struct bpf_arena *arena, long uaddr) } struct apply_range_data { + struct bpf_arena *arena; struct page **pages; - struct page *scratch_page; int i; }; struct clear_range_data { + struct bpf_arena *arena; struct llist_head *free_pages; - struct page *scratch_page; }; static int apply_range_set_cb(pte_t *pte, unsigned long addr, void *data) @@ -180,7 +182,7 @@ static int apply_range_set_cb(pte_t *pte, unsigned long addr, void *data) if (pte_none(old)) continue; - if (WARN_ON_ONCE(pte_page(old) != d->scratch_page)) + if (WARN_ON_ONCE(pte_page(old) != d->arena->scratch_page)) return -EBUSY; ptep_get_and_clear(&init_mm, addr, pte); flush_tlb_before_set(addr); @@ -196,6 +198,7 @@ static int apply_range_set_cb(pte_t *pte, unsigned long addr, void *data) set_pte_at(&init_mm, addr, pte, pteval); #endif d->i++; + d->arena->nr_pages++; return 0; } @@ -227,10 +230,11 @@ static int apply_range_clear_cb(pte_t *pte, unsigned long addr, void *data) * scratches its PTE. A later bpf_arena_free_pages() over that range walks * here. Without the skip, scratch_page would be freed. */ - if (page == d->scratch_page) + if (page == d->arena->scratch_page) return 0; __llist_add(&page->pcp_llist, d->free_pages); + d->arena->nr_pages--; return 0; } @@ -413,7 +417,9 @@ static int arena_map_check_btf(struct bpf_map *map, const struct btf *btf, static u64 arena_map_mem_usage(const struct bpf_map *map) { - return 0; + struct bpf_arena *arena = container_of(map, struct bpf_arena, map); + + return (u64)READ_ONCE(arena->nr_pages) << PAGE_SHIFT; } struct vma_list { @@ -506,8 +512,7 @@ static vm_fault_t arena_vm_fault(struct vm_fault *vmf) if (ret) goto out_sigsegv_memcg; - struct apply_range_data data = { .pages = &page, .i = 0, - .scratch_page = arena->scratch_page }; + struct apply_range_data data = { .arena = arena, .pages = &page, .i = 0 }; /* Account into memcg of the process that created bpf_arena */ ret = bpf_map_alloc_pages(map, NUMA_NO_NODE, 1, &page); if (ret) { @@ -696,8 +701,8 @@ static long arena_alloc_pages(struct bpf_arena *arena, long uaddr, long page_cnt bpf_map_memcg_exit(old_memcg, new_memcg); return 0; } + data.arena = arena; data.pages = pages; - data.scratch_page = arena->scratch_page; if (raw_res_spin_lock_irqsave(&arena->spinlock, flags)) goto out_free_pages; @@ -873,8 +878,8 @@ static void arena_free_pages(struct bpf_arena *arena, long uaddr, long page_cnt, range_tree_set(&arena->rt, pgoff, page_cnt); init_llist_head(&free_pages); + cdata.arena = arena; cdata.free_pages = &free_pages; - cdata.scratch_page = arena->scratch_page; /* clear ptes and collect struct pages */ apply_to_existing_page_range(&init_mm, kaddr, page_cnt << PAGE_SHIFT, apply_range_clear_cb, &cdata); @@ -981,8 +986,8 @@ static void arena_free_worker(struct work_struct *work) bpf_map_memcg_enter(&arena->map, &old_memcg, &new_memcg); init_llist_head(&free_pages); + cdata.arena = arena; cdata.free_pages = &free_pages; - cdata.scratch_page = arena->scratch_page; arena_vm_start = bpf_arena_get_kern_vm_start(arena); user_vm_start = bpf_arena_get_user_vm_start(arena); -- 2.43.0
