From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from out-171.mta1.migadu.com (out-171.mta1.migadu.com [95.215.58.171]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 8286942D759 for ; Thu, 16 Jul 2026 14:28:27 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=95.215.58.171 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784212109; cv=none; b=Z3rmRb6fiRpsLEgelKNKvj5NMXJjFXbvh9R0+80qC64MCfHmTyCOlzooREtxRHZ28APjU1c/XriNw7Ur0R36M9BmiQj9QLUF7qUUh+RNvpGoGAnUILkxPcAUhqWJ8+SnlJb+yp3gNFmsFKCfQhvZehpQihTFtGCNTgfbI/dYYzQ= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1784212109; c=relaxed/simple; bh=lTkri3eLcyfnznfqpApEqA81+0LQWnP5CrSlpTRIU3g=; h=From:To:Cc:Subject:Date:Message-ID:MIME-Version; b=rxyLPYotrYbXCqZUunJSEqIhCkro7yrl6HHn4LaNlz6xkziasIUCT2EJ2jB946yXMiAEvNHY2qNga12P6cjNWXc4Hpcolv6hbCdAfsv7QoQpaBYBv7+c6uP1RUjg5zviLpZw+WZejslvepu3UaVTWZE2F+md+7x61paZUBeRg2k= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev; spf=pass smtp.mailfrom=linux.dev; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b=Ey7kylJD; arc=none smtp.client-ip=95.215.58.171 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=linux.dev Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=linux.dev Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=linux.dev header.i=@linux.dev header.b="Ey7kylJD" X-Report-Abuse: Please report any abuse attempt to abuse@migadu.com and include these headers. DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=linux.dev; s=key1; t=1784212095; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version: content-transfer-encoding:content-transfer-encoding; bh=Cn8IWL7vldf7zy6/xPcDXPEoWEq0JvN6ZK8h9U3/xgo=; b=Ey7kylJDsBds2FC0n5ih0PJ1Y3WKxFHy3DIOuqIIiz5gG7rB4Ya59zm09SJqWEvpb53z0y wrXPu2r0JoMkCtDPnCa8FkoLWr+t2ob2U1Buav7T8inq9trWtt73AhF6JBUAyoOjgeiYxo 6JwBw52Wq+0vLANNXPRaRclFSyHYMuE= From: Jiayuan Chen To: bpf@vger.kernel.org, memxor@gmail.com Cc: Jiayuan Chen , Alexei Starovoitov , Daniel Borkmann , Andrii Nakryiko , Eduard Zingerman , Martin KaFai Lau , Song Liu , Yonghong Song , Jiri Olsa , Emil Tsalapatis , Shuah Khan , Woojin Ji , Puranjay Mohan , Saket Kumar Bhaskar , Ihor Solodrai , linux-kernel@vger.kernel.org, linux-kselftest@vger.kernel.org Subject: [PATCH bpf-next 1/3] bpf: Add memory usage for arena Date: Thu, 16 Jul 2026 22:24:58 +0800 Message-ID: <20260716142746.8794-1-jiayuan.chen@linux.dev> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Migadu-Flow: FLOW_OUT 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 --- 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