From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp.kernel.org (aws-us-west-2-korg-mail-1.web.codeaurora.org [10.30.226.201]) (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 E2B351C29 for ; Wed, 23 Nov 2022 09:32:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 54708C433C1; Wed, 23 Nov 2022 09:32:30 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1669195950; bh=FzlzNwFEQZf+iUksPz8L9P4mFXjh2drbjWh1XaP4tc0=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=mitcosYxp3pxp1dM32gf+A0/porIyjP0gUTuZqBsfBJMjhqYgbeVqCnQ2lNX5UyDR W5fiYyYJZ9OZqTKiTJ8plt6lUP0DBVlCxI17QedFo91LtD8+HSGQr3ei3ttB0CgR6I 85Jzz01hHFYnqHUM0J8sRMw4aY/8oPms+ymW24Zc= From: Greg Kroah-Hartman To: stable@vger.kernel.org Cc: Greg Kroah-Hartman , patches@lists.linux.dev, Xu Kuohai , Andrii Nakryiko , Yonghong Song , Sasha Levin Subject: [PATCH 5.15 078/181] bpf: Initialize same number of free nodes for each pcpu_freelist Date: Wed, 23 Nov 2022 09:50:41 +0100 Message-Id: <20221123084605.727587405@linuxfoundation.org> X-Mailer: git-send-email 2.38.1 In-Reply-To: <20221123084602.707860461@linuxfoundation.org> References: <20221123084602.707860461@linuxfoundation.org> User-Agent: quilt/0.67 Precedence: bulk X-Mailing-List: patches@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit From: Xu Kuohai [ Upstream commit 4b45cd81f737d79d0fbfc0d320a1e518e7f0bbf0 ] pcpu_freelist_populate() initializes nr_elems / num_possible_cpus() + 1 free nodes for some CPUs, and then possibly one CPU with fewer nodes, followed by remaining cpus with 0 nodes. For example, when nr_elems == 256 and num_possible_cpus() == 32, CPU 0~27 each gets 9 free nodes, CPU 28 gets 4 free nodes, CPU 29~31 get 0 free nodes, while in fact each CPU should get 8 nodes equally. This patch initializes nr_elems / num_possible_cpus() free nodes for each CPU firstly, then allocates the remaining free nodes by one for each CPU until no free nodes left. Fixes: e19494edab82 ("bpf: introduce percpu_freelist") Signed-off-by: Xu Kuohai Signed-off-by: Andrii Nakryiko Acked-by: Yonghong Song Link: https://lore.kernel.org/bpf/20221110122128.105214-1-xukuohai@huawei.com Signed-off-by: Sasha Levin --- kernel/bpf/percpu_freelist.c | 23 +++++++++++------------ 1 file changed, 11 insertions(+), 12 deletions(-) diff --git a/kernel/bpf/percpu_freelist.c b/kernel/bpf/percpu_freelist.c index 3d897de89061..bbab8bb4b2fd 100644 --- a/kernel/bpf/percpu_freelist.c +++ b/kernel/bpf/percpu_freelist.c @@ -102,22 +102,21 @@ void pcpu_freelist_populate(struct pcpu_freelist *s, void *buf, u32 elem_size, u32 nr_elems) { struct pcpu_freelist_head *head; - int i, cpu, pcpu_entries; + unsigned int cpu, cpu_idx, i, j, n, m; - pcpu_entries = nr_elems / num_possible_cpus() + 1; - i = 0; + n = nr_elems / num_possible_cpus(); + m = nr_elems % num_possible_cpus(); + cpu_idx = 0; for_each_possible_cpu(cpu) { -again: head = per_cpu_ptr(s->freelist, cpu); - /* No locking required as this is not visible yet. */ - pcpu_freelist_push_node(head, buf); - i++; - buf += elem_size; - if (i == nr_elems) - break; - if (i % pcpu_entries) - goto again; + j = n + (cpu_idx < m ? 1 : 0); + for (i = 0; i < j; i++) { + /* No locking required as this is not visible yet. */ + pcpu_freelist_push_node(head, buf); + buf += elem_size; + } + cpu_idx++; } } -- 2.35.1