From patchwork Fri Sep 8 13:39:20 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 8bit X-Patchwork-Submitter: Hou Tao X-Patchwork-Id: 13377480 X-Patchwork-Delegate: bpf@iogearbox.net Received: from lindbergh.monkeyblade.net (lindbergh.monkeyblade.net [23.128.96.19]) (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 856F65254 for ; Fri, 8 Sep 2023 13:39:39 +0000 (UTC) Received: from dggsgout12.his.huawei.com (dggsgout12.his.huawei.com [45.249.212.56]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 376A919BC for ; Fri, 8 Sep 2023 06:39:37 -0700 (PDT) Received: from mail02.huawei.com (unknown [172.30.67.143]) by dggsgout12.his.huawei.com (SkyGuard) with ESMTP id 4Rhxzk0VS2z4f3knY for ; Fri, 8 Sep 2023 21:39:30 +0800 (CST) Received: from huaweicloud.com (unknown [10.175.124.27]) by APP4 (Coremail) with SMTP id gCh0CgDHVqkPJPtkRmSwCg--.44307S5; Fri, 08 Sep 2023 21:39:33 +0800 (CST) From: Hou Tao To: bpf@vger.kernel.org Cc: Martin KaFai Lau , Alexei Starovoitov , Andrii Nakryiko , Song Liu , Hao Luo , Yonghong Song , Daniel Borkmann , KP Singh , Stanislav Fomichev , Jiri Olsa , John Fastabend , =?utf-8?b?QmrDtnJuIFTDtnBlbA==?= , houtao1@huawei.com Subject: [PATCH bpf 1/4] bpf: Adjust size_index according to the value of KMALLOC_MIN_SIZE Date: Fri, 8 Sep 2023 21:39:20 +0800 Message-Id: <20230908133923.2675053-2-houtao@huaweicloud.com> X-Mailer: git-send-email 2.29.2 In-Reply-To: <20230908133923.2675053-1-houtao@huaweicloud.com> References: <20230908133923.2675053-1-houtao@huaweicloud.com> Precedence: bulk X-Mailing-List: bpf@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-CM-TRANSID: gCh0CgDHVqkPJPtkRmSwCg--.44307S5 X-Coremail-Antispam: 1UD129KBjvJXoW3Jr17Cr18Jr4DKFW8AF4rAFb_yoW7Xr1kpF y3Jr18Gr48ZF4xJr47CF4rJFWrGw1Fk3W7JrWfXw1UZF15Gr1DJr1ktryruFyqqrWrZ3W7 JF4qqw48Kr1UJaDanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUU9Eb4IE77IF4wAFF20E14v26rWj6s0DM7CY07I20VC2zVCF04k2 6cxKx2IYs7xG6rWj6s0DM7CIcVAFz4kK6r1j6r18M28IrcIa0xkI8VA2jI8067AKxVWUGw A2048vs2IY020Ec7CjxVAFwI0_Gr0_Xr1l8cAvFVAK0II2c7xJM28CjxkF64kEwVA0rcxS w2x7M28EF7xvwVC0I7IYx2IY67AKxVW8JVW5JwA2z4x0Y4vE2Ix0cI8IcVCY1x0267AKxV W8JVWxJwA2z4x0Y4vEx4A2jsIE14v26rxl6s0DM28EF7xvwVC2z280aVCY1x0267AKxVW0 oVCq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7V C0I7IYx2IY67AKxVWUJVWUGwAv7VC2z280aVAFwI0_Jr0_Gr1lOx8S6xCaFVCjc4AY6r1j 6r4UM4x0Y48IcxkI7VAKI48JM4IIrI8v6xkF7I0E8cxan2IY04v7MxAIw28IcxkI7VAKI4 8JMxC20s026xCaFVCjc4AY6r1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xv wVAFwI0_JrI_JrWlx4CE17CEb7AF67AKxVWUtVW8ZwCIc40Y0x0EwIxGrwCI42IY6xIIjx v20xvE14v26r1j6r1xMIIF0xvE2Ix0cI8IcVCY1x0267AKxVW8JVWxJwCI42IY6xAIw20E Y4v20xvaj40_Jr0_JF4lIxAIcVC2z280aVAFwI0_Jr0_Gr1lIxAIcVC2z280aVCY1x0267 AKxVW8JVW8JrUvcSsGvfC2KfnxnUUI43ZEXa7IU8-TmDUUUUU== X-CM-SenderInfo: xkrx3t3r6k3tpzhluzxrxghudrp/ X-CFilter-Loop: Reflected X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00,RCVD_IN_MSPIKE_H2, SPF_HELO_NONE,SPF_NONE autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net X-Patchwork-Delegate: bpf@iogearbox.net From: Hou Tao The following warning was reported when running "./test_progs -a link_api -a linked_list" on a RISC-V QEMU VM: ------------[ cut here ]------------ WARNING: CPU: 3 PID: 261 at kernel/bpf/memalloc.c:342 bpf_mem_refill Modules linked in: bpf_testmod(OE) CPU: 3 PID: 261 Comm: test_progs- ... 6.5.0-rc5-01743-gdcb152bb8328 #2 Hardware name: riscv-virtio,qemu (DT) epc : bpf_mem_refill+0x1fc/0x206 ra : irq_work_single+0x68/0x70 epc : ffffffff801b1bc4 ra : ffffffff8015fe84 sp : ff2000000001be20 gp : ffffffff82d26138 tp : ff6000008477a800 t0 : 0000000000046600 t1 : ffffffff812b6ddc t2 : 0000000000000000 s0 : ff2000000001be70 s1 : ff5ffffffffe8998 a0 : ff5ffffffffe8998 a1 : ff600003fef4b000 a2 : 000000000000003f a3 : ffffffff80008250 a4 : 0000000000000060 a5 : 0000000000000080 a6 : 0000000000000000 a7 : 0000000000735049 s2 : ff5ffffffffe8998 s3 : 0000000000000022 s4 : 0000000000001000 s5 : 0000000000000007 s6 : ff5ffffffffe8570 s7 : ffffffff82d6bd30 s8 : 000000000000003f s9 : ffffffff82d2c5e8 s10: 000000000000ffff s11: ffffffff82d2c5d8 t3 : ffffffff81ea8f28 t4 : 0000000000000000 t5 : ff6000008fd28278 t6 : 0000000000040000 [] bpf_mem_refill+0x1fc/0x206 [] irq_work_single+0x68/0x70 [] irq_work_run_list+0x28/0x36 [] irq_work_run+0x38/0x66 [] handle_IPI+0x3a/0xb4 [] handle_percpu_devid_irq+0xa4/0x1f8 [] generic_handle_domain_irq+0x28/0x36 [] ipi_mux_process+0xac/0xfa [] sbi_ipi_handle+0x2e/0x88 [] generic_handle_domain_irq+0x28/0x36 [] riscv_intc_irq+0x36/0x4e [] handle_riscv_irq+0x54/0x86 [] do_irq+0x66/0x98 ---[ end trace 0000000000000000 ]--- The warning is due to WARN_ON_ONCE(tgt->unit_size != c->unit_size) in free_bulk(). The direct reason is that a object is allocated and freed by bpf_mem_caches with different unit_size. The root cause is that KMALLOC_MIN_SIZE is 64 and there is no 96-bytes slab cache in the specific VM. When linked_list test allocates a 72-bytes object through bpf_obj_new(), bpf_global_ma will allocate it from a bpf_mem_cache with 96-bytes unit_size, but this bpf_mem_cache is backed by 128-bytes slab cache. When the object is freed, bpf_mem_free() uses ksize() to choose the corresponding bpf_mem_cache. Because the object is allocated from 128-bytes slab cache, ksize() returns 128, bpf_mem_free() chooses a 128-bytes bpf_mem_cache to free the object and triggers the warning. A similar warning will also be reported when using CONFIG_SLAB instead of CONFIG_SLUB in a x86-64 kernel. Because CONFIG_SLUB defines KMALLOC_MIN_SIZE as 8 but CONFIG_SLAB defines KMALLOC_MIN_SIZE as 32. An alternative fix is to use kmalloc_size_round() in bpf_mem_alloc() to choose a bpf_mem_cache which has the same unit_size with the backing slab cache, but it may introduce performance degradation, so fix the warning by adjusting the indexes in size_index according to the value of KMALLOC_MIN_SIZE just like setup_kmalloc_cache_index_table() does. Fixes: 822fb26bdb55 ("bpf: Add a hint to allocated objects.") Reported-by: Björn Töpel Closes: https://lore.kernel.org/bpf/87jztjmmy4.fsf@all.your.base.are.belong.to.us Signed-off-by: Hou Tao --- kernel/bpf/memalloc.c | 38 ++++++++++++++++++++++++++++++++++++++ 1 file changed, 38 insertions(+) diff --git a/kernel/bpf/memalloc.c b/kernel/bpf/memalloc.c index 9c49ae53deaf..98d9e96fba3c 100644 --- a/kernel/bpf/memalloc.c +++ b/kernel/bpf/memalloc.c @@ -916,3 +916,41 @@ void notrace *bpf_mem_cache_alloc_flags(struct bpf_mem_alloc *ma, gfp_t flags) return !ret ? NULL : ret + LLIST_NODE_SZ; } + +/* Most of the logic is taken from setup_kmalloc_cache_index_table() */ +static __init int bpf_mem_cache_adjust_size(void) +{ + unsigned int size, index; + + /* Normally KMALLOC_MIN_SIZE is 8-bytes, but it can be + * up-to 256-bytes. + */ + size = KMALLOC_MIN_SIZE; + if (size <= 192) + index = size_index[(size - 1) / 8]; + else + index = fls(size - 1) - 1; + for (size = 8; size < KMALLOC_MIN_SIZE && size <= 192; size += 8) + size_index[(size - 1) / 8] = index; + + /* The minimal alignment is 64-bytes, so disable 96-bytes cache and + * use 128-bytes cache instead. + */ + if (KMALLOC_MIN_SIZE >= 64) { + index = size_index[(128 - 1) / 8]; + for (size = 64 + 8; size <= 96; size += 8) + size_index[(size - 1) / 8] = index; + } + + /* The minimal alignment is 128-bytes, so disable 192-bytes cache and + * use 256-bytes cache instead. + */ + if (KMALLOC_MIN_SIZE >= 128) { + index = fls(256 - 1) - 1; + for (size = 128 + 8; size <= 192; size += 8) + size_index[(size - 1) / 8] = index; + } + + return 0; +} +subsys_initcall(bpf_mem_cache_adjust_size);