From mboxrd@z Thu Jan 1 00:00:00 1970 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 61880C433FE for ; Tue, 8 Nov 2022 11:07:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S234070AbiKHLHI (ORCPT ); Tue, 8 Nov 2022 06:07:08 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:50332 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S233999AbiKHLGl (ORCPT ); Tue, 8 Nov 2022 06:06:41 -0500 Received: from foss.arm.com (foss.arm.com [217.140.110.172]) by lindbergh.monkeyblade.net (Postfix) with ESMTP id 6214347323; Tue, 8 Nov 2022 03:06:40 -0800 (PST) Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 554B113D5; Tue, 8 Nov 2022 03:06:46 -0800 (PST) Received: from pierre123.arm.com (unknown [10.57.5.33]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 5A9DB3F534; Tue, 8 Nov 2022 03:06:37 -0800 (PST) From: Pierre Gondois To: linux-kernel@vger.kernel.org Cc: Pierre Gondois , Catalin Marinas , Will Deacon , Paul Walmsley , Palmer Dabbelt , Albert Ou , "Rafael J. Wysocki" , Len Brown , Sudeep Holla , Greg Kroah-Hartman , Gavin Shan , Peter Chen , SeongJae Park , Jakub Kicinski , linux-arm-kernel@lists.infradead.org, linux-riscv@lists.infradead.org, linux-acpi@vger.kernel.org Subject: [PATCH 5/5] arch_topology: Build cacheinfo from primary CPU Date: Tue, 8 Nov 2022 12:04:21 +0100 Message-Id: <20221108110424.166896-6-pierre.gondois@arm.com> X-Mailer: git-send-email 2.25.1 In-Reply-To: <20221108110424.166896-1-pierre.gondois@arm.com> References: <20221108110424.166896-1-pierre.gondois@arm.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org commit 3fcbf1c77d08 ("arch_topology: Fix cache attributes detection in the CPU hotplug path") adds a call to detect_cache_attributes() to populate the cacheinfo before updating the siblings mask. detect_cache_attributes() allocates memory and can take the PPTT mutex (on ACPI platforms). On PREEMPT_RT kernels, on secondary CPUs, this triggers a: 'BUG: sleeping function called from invalid context' [1] as the code is executed with preemption and interrupts disabled. The primary CPU was previously storing the cache information using the now removed (struct cpu_topology).llc_id: commit 5b8dc787ce4a ("arch_topology: Drop LLC identifier stash from the CPU topology") allocate_cache_info() tries to build the cacheinfo from the primary CPU prior secondary CPUs boot, if the DT/ACPI description contains cache information. If allocate_cache_info() fails, then fallback to the current state for the cacheinfo allocation. [1] will be triggered in such case. When unplugging a CPU, the cacheinfo memory cannot be freed. If it was, then the memory would be allocated early by the re-plugged CPU and would trigger [1]. [1]: [ 7.560791] BUG: sleeping function called from invalid context at kernel/locking/spinlock_rt.c:46 [ 7.560794] in_atomic(): 1, irqs_disabled(): 128, non_block: 0, pid: 0, name: swapper/111 [ 7.560796] preempt_count: 1, expected: 0 [ 7.560797] RCU nest depth: 1, expected: 1 [ 7.560799] 3 locks held by swapper/111/0: [ 7.560800] #0: ffff403e406cae98 (&pcp->lock){+.+.}-{3:3}, at: get_page_from_freelist+0x218/0x12c8 [ 7.560811] #1: ffffc5f8ed09f8e8 (rcu_read_lock){....}-{1:3}, at: rt_spin_trylock+0x48/0xf0 [ 7.560820] #2: ffff403f400b4fd8 (&zone->lock){+.+.}-{3:3}, at: rmqueue_bulk+0x64/0xa80 [ 7.560824] irq event stamp: 0 [ 7.560825] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [ 7.560827] hardirqs last disabled at (0): [] copy_process+0x5dc/0x1ab8 [ 7.560830] softirqs last enabled at (0): [] copy_process+0x5dc/0x1ab8 [ 7.560833] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 7.560834] Preemption disabled at: [ 7.560835] [] migrate_enable+0x30/0x130 [ 7.560838] CPU: 111 PID: 0 Comm: swapper/111 Tainted: G W 6.0.0-rc4-rt6-[...] [ 7.560841] Call trace: [...] [ 7.560870] __kmalloc+0xbc/0x1e8 [ 7.560873] detect_cache_attributes+0x2d4/0x5f0 [ 7.560876] update_siblings_masks+0x30/0x368 [ 7.560880] store_cpu_topology+0x78/0xb8 [ 7.560883] secondary_start_kernel+0xd0/0x198 [ 7.560885] __secondary_switched+0xb0/0xb4 Signed-off-by: Pierre Gondois --- drivers/base/arch_topology.c | 10 ++++++- drivers/base/cacheinfo.c | 53 ++++++++++++++++++++++++++++-------- include/linux/cacheinfo.h | 1 + 3 files changed, 52 insertions(+), 12 deletions(-) diff --git a/drivers/base/arch_topology.c b/drivers/base/arch_topology.c index d07a7cfa389a..4222a6d1e07b 100644 --- a/drivers/base/arch_topology.c +++ b/drivers/base/arch_topology.c @@ -825,7 +825,7 @@ __weak int __init parse_acpi_topology(void) #if defined(CONFIG_ARM64) || defined(CONFIG_RISCV) void __init init_cpu_topology(void) { - int ret; + int cpu, ret; reset_cpu_topology(); ret = parse_acpi_topology(); @@ -840,6 +840,14 @@ void __init init_cpu_topology(void) reset_cpu_topology(); return; } + + for_each_possible_cpu(cpu) { + ret = allocate_cache_info(cpu); + if (ret) { + pr_err("Early cacheinfo failed, ret = %d\n", ret); + break; + } + } } void store_cpu_topology(unsigned int cpuid) diff --git a/drivers/base/cacheinfo.c b/drivers/base/cacheinfo.c index 6f6cd120c4f1..889d94d89e18 100644 --- a/drivers/base/cacheinfo.c +++ b/drivers/base/cacheinfo.c @@ -371,10 +371,6 @@ static void free_cache_attributes(unsigned int cpu) return; cache_shared_cpu_map_remove(cpu); - - kfree(per_cpu_cacheinfo(cpu)); - per_cpu_cacheinfo(cpu) = NULL; - cache_leaves(cpu) = 0; } int __weak init_cache_level(unsigned int cpu) @@ -387,18 +383,53 @@ int __weak populate_cache_leaves(unsigned int cpu) return -ENOENT; } +int allocate_cache_info(unsigned int cpu) +{ + struct cpu_cacheinfo *this_cpu_ci; + unsigned int levels, split_levels; + int ret; + + if (acpi_disabled) + ret = init_of_cache_level(cpu); + else { + ret = acpi_get_cache_info(cpu, &levels, &split_levels); + this_cpu_ci = get_cpu_cacheinfo(cpu); + this_cpu_ci->num_levels = levels; + /* + * This assumes that: + * - there cannot be any split caches (data/instruction) + * above a unified cache + * - data/instruction caches come by pair + */ + this_cpu_ci->num_leaves = levels + split_levels; + } + if (ret < 0) + return ret; + else if (!cache_leaves(cpu)) + return -ENOENT; + + per_cpu_cacheinfo(cpu) = kcalloc(cache_leaves(cpu), + sizeof(struct cacheinfo), GFP_ATOMIC); + if (per_cpu_cacheinfo(cpu) == NULL) { + cache_leaves(cpu) = 0; + return -ENOMEM; + } + + return ret; +} + int detect_cache_attributes(unsigned int cpu) { int ret; - /* Since early detection of the cacheinfo is allowed via this - * function and this also gets called as CPU hotplug callbacks via - * cacheinfo_cpu_online, the initialisation can be skipped and only - * CPU maps can be updated as the CPU online status would be update - * if called via cacheinfo_cpu_online path. + /* Since early initialization/allocation of the cacheinfo is allowed + * via allocate_cache_info() and this also gets called as CPU hotplug + * callbacks via cacheinfo_cpu_online, the init/alloc can be skipped + * as it will happen only once (the cacheinfo memory is never freed). + * Just populate the cacheinfo. */ if (per_cpu_cacheinfo(cpu)) - goto update_cpu_map; + goto populate_leaves; if (init_cache_level(cpu) || !cache_leaves(cpu)) return -ENOENT; @@ -410,6 +441,7 @@ int detect_cache_attributes(unsigned int cpu) return -ENOMEM; } +populate_leaves: /* * populate_cache_leaves() may completely setup the cache leaves and * shared_cpu_map or it may leave it partially setup. @@ -418,7 +450,6 @@ int detect_cache_attributes(unsigned int cpu) if (ret) goto free_ci; -update_cpu_map: /* * For systems using DT for cache hierarchy, fw_token * and shared_cpu_map will be set up here only if they are diff --git a/include/linux/cacheinfo.h b/include/linux/cacheinfo.h index f992d81d211f..7d390806b788 100644 --- a/include/linux/cacheinfo.h +++ b/include/linux/cacheinfo.h @@ -85,6 +85,7 @@ int populate_cache_leaves(unsigned int cpu); int cache_setup_acpi(unsigned int cpu); bool last_level_cache_is_valid(unsigned int cpu); bool last_level_cache_is_shared(unsigned int cpu_x, unsigned int cpu_y); +int allocate_cache_info(unsigned int cpu); int detect_cache_attributes(unsigned int cpu); #ifndef CONFIG_ACPI_PPTT /* -- 2.25.1