From patchwork Mon Mar 6 08:42:12 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Martin KaFai Lau X-Patchwork-Id: 13160703 X-Patchwork-Delegate: bpf@iogearbox.net Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id D1DC3C61DA4 for ; Mon, 6 Mar 2023 08:43:13 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230090AbjCFInM (ORCPT ); Mon, 6 Mar 2023 03:43:12 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:45678 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229559AbjCFInD (ORCPT ); Mon, 6 Mar 2023 03:43:03 -0500 Received: from out-50.mta1.migadu.com (out-50.mta1.migadu.com [95.215.58.50]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id E597D59EF for ; Mon, 6 Mar 2023 00:42:58 -0800 (PST) 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=1678092177; 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: in-reply-to:in-reply-to:references:references; bh=EQ0jHJF2RNqulvTAJbWzRudyaum3fTbr9WEckrKwMwo=; b=LQfHcB2Up2/Illcz7K+kQbqjVjJ3WvWAoieJGMFTZ4dZE1aCtT+OBw8Vki3fiS1OTPfwd5 AqeOoL16LlazYiRzTIM+4k2sJZdKk4+fe9cgNyqYyfVnlhf83kc7yTCkd5f5092DRrSxsf c54h+awtBb+NeM1Jx0fXeS0YfTLGFug= From: Martin KaFai Lau To: bpf@vger.kernel.org Cc: Alexei Starovoitov , Andrii Nakryiko , Daniel Borkmann , kernel-team@meta.com, Namhyung Kim Subject: [PATCH bpf-next 12/16] bpf: Use bpf_mem_cache_alloc/free in bpf_selem_alloc/free Date: Mon, 6 Mar 2023 00:42:12 -0800 Message-Id: <20230306084216.3186830-13-martin.lau@linux.dev> In-Reply-To: <20230306084216.3186830-1-martin.lau@linux.dev> References: <20230306084216.3186830-1-martin.lau@linux.dev> MIME-Version: 1.0 X-Migadu-Flow: FLOW_OUT Precedence: bulk List-ID: X-Mailing-List: bpf@vger.kernel.org X-Patchwork-Delegate: bpf@iogearbox.net From: Martin KaFai Lau This patch uses bpf_mem_cache_alloc/free in bpf_selem_alloc/free. The ____cacheline_aligned attribute is no longer needed in 'struct bpf_local_storage_elem'. bpf_mem_cache_alloc will have 'struct llist_node' in front of the 'struct bpf_local_storage_elem'. It will use the 8bytes hole in the bpf_local_storage_elem. After bpf_mem_cache_alloc(), the SDATA(selem)->data is zero-ed because bpf_mem_cache_alloc() could return a reused selem. It is to keep the existing bpf_map_kzalloc() behavior. Only SDATA(selem)->data is zero-ed. SDATA(selem)->data is the visible part to the bpf prog. No need to use zero_map_value() to do the zeroing because bpf_selem_free() ensures no bpf prog is using the selem before returning the selem through bpf_mem_cache_free(). For the internal fields of selem, they will be initialized when linking to the new smap and the new local_storage. When bpf_mem_cache_alloc() fails, bpf_selem_alloc() will try to fallback to kzalloc only if the caller has GFP_KERNEL flag set (ie. from sleepable bpf prog that should not cause deadlock). BPF_MA_SIZE and BPF_MA_PTR macro are added for that. For the common selem free path where the selem is freed when its owner is also being freed, reuse_now == true and selem can be reused immediately. bpf_selem_free() uses bpf_mem_cache_free() where selem will be considered for immediate reuse. For the uncommon path that the bpf prog explicitly deletes the selem (by using the helper bpf_*_storage_delete), the selem cannot be reused immediately. reuse_now == false and bpf_selem_free() will stay with the current call_rcu_tasks_trace. BPF_MA_NODE macro is added to get the correct address for the kfree. mem_charge and mem_uncharge are changed to use the BPF_MA_SIZE macro. It will have a temporarily over-charge for the bpf_local_storage_alloc() because bpf_local_storage is not moved to bpf_mem_cache_alloc in this patch but it will be done in the next patch. Cc: Namhyung Kim Signed-off-by: Martin KaFai Lau --- include/linux/bpf_local_storage.h | 8 ++--- include/linux/bpf_mem_alloc.h | 5 +++ kernel/bpf/bpf_local_storage.c | 56 +++++++++++++++++++++++++------ 3 files changed, 53 insertions(+), 16 deletions(-) diff --git a/include/linux/bpf_local_storage.h b/include/linux/bpf_local_storage.h index adb5023a1af5..a236c9b964cf 100644 --- a/include/linux/bpf_local_storage.h +++ b/include/linux/bpf_local_storage.h @@ -13,6 +13,7 @@ #include #include #include +#include #include #define BPF_LOCAL_STORAGE_CACHE_SIZE 16 @@ -55,6 +56,7 @@ struct bpf_local_storage_map { u32 bucket_log; u16 elem_size; u16 cache_idx; + struct bpf_mem_alloc selem_ma; }; struct bpf_local_storage_data { @@ -74,11 +76,7 @@ struct bpf_local_storage_elem { struct hlist_node snode; /* Linked to bpf_local_storage */ struct bpf_local_storage __rcu *local_storage; struct rcu_head rcu; - /* 8 bytes hole */ - /* The data is stored in another cacheline to minimize - * the number of cachelines access during a cache hit. - */ - struct bpf_local_storage_data sdata ____cacheline_aligned; + struct bpf_local_storage_data sdata; }; struct bpf_local_storage { diff --git a/include/linux/bpf_mem_alloc.h b/include/linux/bpf_mem_alloc.h index a7104af61ab4..0ab16fb0ab50 100644 --- a/include/linux/bpf_mem_alloc.h +++ b/include/linux/bpf_mem_alloc.h @@ -5,6 +5,11 @@ #include #include +#define BPF_MA_NODE_SZ sizeof(struct llist_node) +#define BPF_MA_SIZE(_size) ((_size) + BPF_MA_NODE_SZ) +#define BPF_MA_PTR(_node) ((void *)(_node) + BPF_MA_NODE_SZ) +#define BPF_MA_NODE(_ptr) ((void *)(_ptr) - BPF_MA_NODE_SZ) + struct bpf_mem_cache; struct bpf_mem_caches; diff --git a/kernel/bpf/bpf_local_storage.c b/kernel/bpf/bpf_local_storage.c index 532b82084ba7..d3c0dd5737d6 100644 --- a/kernel/bpf/bpf_local_storage.c +++ b/kernel/bpf/bpf_local_storage.c @@ -31,7 +31,7 @@ static int mem_charge(struct bpf_local_storage_map *smap, void *owner, u32 size) if (!map->ops->map_local_storage_charge) return 0; - return map->ops->map_local_storage_charge(smap, owner, size); + return map->ops->map_local_storage_charge(smap, owner, BPF_MA_SIZE(size)); } static void mem_uncharge(struct bpf_local_storage_map *smap, void *owner, @@ -40,7 +40,7 @@ static void mem_uncharge(struct bpf_local_storage_map *smap, void *owner, struct bpf_map *map = &smap->map; if (map->ops->map_local_storage_uncharge) - map->ops->map_local_storage_uncharge(smap, owner, size); + map->ops->map_local_storage_uncharge(smap, owner, BPF_MA_SIZE(size)); } static struct bpf_local_storage __rcu ** @@ -80,12 +80,32 @@ bpf_selem_alloc(struct bpf_local_storage_map *smap, void *owner, if (charge_mem && mem_charge(smap, owner, smap->elem_size)) return NULL; - selem = bpf_map_kzalloc(&smap->map, smap->elem_size, - gfp_flags | __GFP_NOWARN); + migrate_disable(); + selem = bpf_mem_cache_alloc(&smap->selem_ma); + migrate_enable(); + if (!selem && (gfp_flags & GFP_KERNEL)) { + void *ma_node; + + ma_node = bpf_map_kzalloc(&smap->map, + BPF_MA_SIZE(smap->elem_size), + gfp_flags | __GFP_NOWARN); + if (ma_node) + selem = BPF_MA_PTR(ma_node); + } + if (selem) { if (value) copy_map_value(&smap->map, SDATA(selem)->data, value); - /* No need to call check_and_init_map_value as memory is zero init */ + else + /* Keep the original bpf_map_kzalloc behavior + * before started using the bpf_mem_cache_alloc. + * + * No need to use zero_map_value. The bpf_selem_free() + * only does bpf_mem_cache_free when there is + * no other bpf prog is using the selem. + */ + memset(SDATA(selem)->data, 0, smap->map.value_size); + return selem; } @@ -129,7 +149,7 @@ static void bpf_selem_free_rcu(struct rcu_head *rcu) struct bpf_local_storage_elem *selem; selem = container_of(rcu, struct bpf_local_storage_elem, rcu); - kfree(selem); + kfree(BPF_MA_NODE(selem)); } static void bpf_selem_free_trace_rcu(struct rcu_head *rcu) @@ -145,10 +165,13 @@ void bpf_selem_free(struct bpf_local_storage_elem *selem, bool reuse_now) { bpf_obj_free_fields(smap->map.record, SDATA(selem)->data); - if (!reuse_now) + if (!reuse_now) { call_rcu_tasks_trace(&selem->rcu, bpf_selem_free_trace_rcu); - else - call_rcu(&selem->rcu, bpf_selem_free_rcu); + } else { + migrate_disable(); + bpf_mem_cache_free(&smap->selem_ma, selem); + migrate_enable(); + } } /* local_storage->lock must be held and selem->local_storage == local_storage. @@ -651,6 +674,7 @@ bpf_local_storage_map_alloc(union bpf_attr *attr, struct bpf_local_storage_map *smap; unsigned int i; u32 nbuckets; + int err; smap = bpf_map_area_alloc(sizeof(*smap), NUMA_NO_NODE); if (!smap) @@ -665,8 +689,8 @@ bpf_local_storage_map_alloc(union bpf_attr *attr, smap->buckets = bpf_map_kvcalloc(&smap->map, sizeof(*smap->buckets), nbuckets, GFP_USER | __GFP_NOWARN); if (!smap->buckets) { - bpf_map_area_free(smap); - return ERR_PTR(-ENOMEM); + err = -ENOMEM; + goto free_smap; } for (i = 0; i < nbuckets; i++) { @@ -677,8 +701,17 @@ bpf_local_storage_map_alloc(union bpf_attr *attr, smap->elem_size = offsetof(struct bpf_local_storage_elem, sdata.data[attr->value_size]); + err = bpf_mem_alloc_init(&smap->selem_ma, smap->elem_size, false); + if (err) + goto free_smap; + smap->cache_idx = bpf_local_storage_cache_idx_get(cache); return &smap->map; + +free_smap: + kvfree(smap->buckets); + bpf_map_area_free(smap); + return ERR_PTR(err); } void bpf_local_storage_map_free(struct bpf_map *map, @@ -744,6 +777,7 @@ void bpf_local_storage_map_free(struct bpf_map *map, */ synchronize_rcu(); + bpf_mem_alloc_destroy(&smap->selem_ma); kvfree(smap->buckets); bpf_map_area_free(smap); }