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 X-Spam-Level: X-Spam-Status: No, score=-16.7 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id BDE7DC43460 for ; Fri, 30 Apr 2021 05:23:28 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9D53D61452 for ; Fri, 30 Apr 2021 05:23:28 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S230158AbhD3FYN (ORCPT ); Fri, 30 Apr 2021 01:24:13 -0400 Received: from mga05.intel.com ([192.55.52.43]:54056 "EHLO mga05.intel.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229508AbhD3FYJ (ORCPT ); Fri, 30 Apr 2021 01:24:09 -0400 IronPort-SDR: N+CUCtVdKnwvptb8gMxXnaq4Kub7vFcdUFgt0L3rptn49me2WJAA0ugiq/daSRa1IDG+eCqbPo KPfHLmPeGvsw== X-IronPort-AV: E=McAfee;i="6200,9189,9969"; a="282543275" X-IronPort-AV: E=Sophos;i="5.82,260,1613462400"; d="scan'208";a="282543275" Received: from fmsmga001.fm.intel.com ([10.253.24.23]) by fmsmga105.fm.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 29 Apr 2021 22:23:22 -0700 IronPort-SDR: Asc7xu+QtQhY/uSENFDc8DeybYZN49Pg7ikbm8QclWADtQWvCj2+n4jJFUa0LfVjIvLO7Fuusx F0ZFsEMsEppQ== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="5.82,260,1613462400"; d="scan'208";a="527506061" Received: from clx-ap-likexu.sh.intel.com ([10.239.48.108]) by fmsmga001.fm.intel.com with ESMTP; 29 Apr 2021 22:23:18 -0700 From: Like Xu To: Peter Zijlstra Cc: Ingo Molnar , Arnaldo Carvalho de Melo , Mark Rutland , Alexander Shishkin , Jiri Olsa , Namhyung Kim , linux-kernel@vger.kernel.org, Kan Liang , Borislav Petkov , seanjc@google.com, x86@kernel.org, Like Xu Subject: [PATCH v2 2/2] perf/x86/lbr: Move cpuc->lbr_xsave allocation out of sleeping region Date: Fri, 30 Apr 2021 13:22:47 +0800 Message-Id: <20210430052247.3079672-2-like.xu@linux.intel.com> X-Mailer: git-send-email 2.30.2 In-Reply-To: <20210430052247.3079672-1-like.xu@linux.intel.com> References: <20210430052247.3079672-1-like.xu@linux.intel.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If the kernel is compiled with the CONFIG_LOCKDEP option, the conditional might_sleep_if() deep in kmem_cache_alloc() will generate the following trace, and potentially cause a deadlock when another LBR event is added: [ 243.115549] BUG: sleeping function called from invalid context at include/linux/sched/mm.h:196 [ 243.117576] in_atomic(): 1, irqs_disabled(): 1, non_block: 0, pid: 839, name: perf [ 243.119326] INFO: lockdep is turned off. [ 243.120249] irq event stamp: 0 [ 243.120967] hardirqs last enabled at (0): [<0000000000000000>] 0x0 [ 243.122415] hardirqs last disabled at (0): [] copy_process+0xa45/0x1dc0 [ 243.124302] softirqs last enabled at (0): [] copy_process+0xa45/0x1dc0 [ 243.126255] softirqs last disabled at (0): [<0000000000000000>] 0x0 [ 243.128119] CPU: 0 PID: 839 Comm: perf Not tainted 5.11.0-rc4-guest+ #8 [ 243.129654] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 0.0.0 02/06/2015 [ 243.131520] Call Trace: [ 243.132112] dump_stack+0x8d/0xb5 [ 243.132896] ___might_sleep.cold.106+0xb3/0xc3 [ 243.133984] slab_pre_alloc_hook.constprop.85+0x96/0xd0 [ 243.135208] ? intel_pmu_lbr_add+0x152/0x170 [ 243.136207] kmem_cache_alloc+0x36/0x250 [ 243.137126] intel_pmu_lbr_add+0x152/0x170 [ 243.138088] x86_pmu_add+0x83/0xd0 [ 243.138889] ? lock_acquire+0x158/0x350 [ 243.139791] ? lock_acquire+0x158/0x350 [ 243.140694] ? lock_acquire+0x158/0x350 [ 243.141625] ? lock_acquired+0x1e3/0x360 [ 243.142544] ? lock_release+0x1bf/0x340 [ 243.143726] ? trace_hardirqs_on+0x1a/0xd0 [ 243.144823] ? lock_acquired+0x1e3/0x360 [ 243.145742] ? lock_release+0x1bf/0x340 [ 243.147107] ? __slab_free+0x49/0x540 [ 243.147966] ? trace_hardirqs_on+0x1a/0xd0 [ 243.148924] event_sched_in.isra.129+0xf8/0x2a0 [ 243.149989] merge_sched_in+0x261/0x3e0 [ 243.150889] ? trace_hardirqs_on+0x1a/0xd0 [ 243.151869] visit_groups_merge.constprop.135+0x130/0x4a0 [ 243.153122] ? sched_clock_cpu+0xc/0xb0 [ 243.154023] ctx_sched_in+0x101/0x210 [ 243.154884] ctx_resched+0x6f/0xc0 [ 243.155686] perf_event_exec+0x21e/0x2e0 [ 243.156641] begin_new_exec+0x5e5/0xbd0 [ 243.157540] load_elf_binary+0x6af/0x1770 [ 243.158478] ? __kernel_read+0x19d/0x2b0 [ 243.159977] ? lock_acquire+0x158/0x350 [ 243.160876] ? __kernel_read+0x19d/0x2b0 [ 243.161796] bprm_execve+0x3c8/0x840 [ 243.162638] do_execveat_common.isra.38+0x1a5/0x1c0 [ 243.163776] __x64_sys_execve+0x32/0x40 [ 243.164676] do_syscall_64+0x33/0x40 [ 243.165514] entry_SYSCALL_64_after_hwframe+0x44/0xa9 [ 243.166746] RIP: 0033:0x7f6180a26feb [ 243.167590] Code: Unable to access opcode bytes at RIP 0x7f6180a26fc1. [ 243.169097] RSP: 002b:00007ffc6558ce18 EFLAGS: 00000202 ORIG_RAX: 000000000000003b [ 243.170844] RAX: ffffffffffffffda RBX: 00007ffc65592d30 RCX: 00007f6180a26feb [ 243.172514] RDX: 000055657f408dc0 RSI: 00007ffc65592410 RDI: 00007ffc65592d30 [ 243.174162] RBP: 00007ffc6558ce80 R08: 00007ffc6558cde0 R09: 0000000000000000 [ 243.176042] R10: 0000000000000008 R11: 0000000000000202 R12: 00007ffc65592410 [ 243.177696] R13: 000055657f408dc0 R14: 0000000000000001 R15: 00007ffc65592410 One of the solution is to use GFP_ATOMIC, but it will make the code less reliable under memory pressue. Let's move the memory allocation out of the sleeping region and put it into the intel_pmu_hw_config(). The LBR xsave buffer is a per-CPU buffer, not a per-event buffer. This buffer is allocated once when initializing the LBR event. The disadvantage of this fix is that the cpuc->lbr_xsave memory will be allocated for each cpu like the legacy ds_buffer. Fixes: c085fb8774 ("perf/x86/intel/lbr: Support XSAVES for arch LBR read") Tested-by: Kan Liang Signed-off-by: Like Xu --- v1->v2 Changelog: - Frob reserve_lbr_buffers() in intel_pmu_hw_config(). arch/x86/events/intel/core.c | 2 ++ arch/x86/events/intel/lbr.c | 25 +++++++++++++++++++------ arch/x86/events/perf_event.h | 6 ++++++ 3 files changed, 27 insertions(+), 6 deletions(-) diff --git a/arch/x86/events/intel/core.c b/arch/x86/events/intel/core.c index 456aa6ffd9a1..19027aa01f82 100644 --- a/arch/x86/events/intel/core.c +++ b/arch/x86/events/intel/core.c @@ -3745,6 +3745,8 @@ static int intel_pmu_hw_config(struct perf_event *event) event->destroy = hw_perf_lbr_event_destroy; } + + reserve_lbr_buffers(event); } if (event->attr.aux_output) { diff --git a/arch/x86/events/intel/lbr.c b/arch/x86/events/intel/lbr.c index bb4486c4155a..1c39155c9f67 100644 --- a/arch/x86/events/intel/lbr.c +++ b/arch/x86/events/intel/lbr.c @@ -658,7 +658,6 @@ static inline bool branch_user_callstack(unsigned br_sel) void intel_pmu_lbr_add(struct perf_event *event) { - struct kmem_cache *kmem_cache = event->pmu->task_ctx_cache; struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); if (!x86_pmu.lbr_nr) @@ -696,11 +695,6 @@ void intel_pmu_lbr_add(struct perf_event *event) perf_sched_cb_inc(event->ctx->pmu); if (!cpuc->lbr_users++ && !event->total_time_running) intel_pmu_lbr_reset(); - - if (static_cpu_has(X86_FEATURE_ARCH_LBR) && - kmem_cache && !cpuc->lbr_xsave && - (cpuc->lbr_users != cpuc->lbr_pebs_users)) - cpuc->lbr_xsave = kmem_cache_alloc(kmem_cache, GFP_KERNEL); } void release_lbr_buffers(void) @@ -722,6 +716,25 @@ void release_lbr_buffers(void) } } +void reserve_lbr_buffers(struct perf_event *event) +{ + struct kmem_cache *kmem_cache; + struct cpu_hw_events *cpuc; + int cpu; + + if (!static_cpu_has(X86_FEATURE_ARCH_LBR)) + return; + + for_each_possible_cpu(cpu) { + cpuc = per_cpu_ptr(&cpu_hw_events, cpu); + kmem_cache = x86_get_pmu(cpu)->task_ctx_cache; + if (kmem_cache && !cpuc->lbr_xsave && !event->attr.precise_ip) + cpuc->lbr_xsave = + kmem_cache_alloc_node(kmem_cache, GFP_KERNEL, + cpu_to_node(cpu)); + } +} + void intel_pmu_lbr_del(struct perf_event *event) { struct cpu_hw_events *cpuc = this_cpu_ptr(&cpu_hw_events); diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h index 27fa85e7d4fd..727e5490e78c 100644 --- a/arch/x86/events/perf_event.h +++ b/arch/x86/events/perf_event.h @@ -1244,6 +1244,8 @@ void reserve_ds_buffers(void); void release_lbr_buffers(void); +void reserve_lbr_buffers(struct perf_event *event); + extern struct event_constraint bts_constraint; extern struct event_constraint vlbr_constraint; @@ -1393,6 +1395,10 @@ static inline void release_lbr_buffers(void) { } +static inline void reserve_lbr_buffers(struct perf_event *event) +{ +} + static inline int intel_pmu_init(void) { return 0; -- 2.30.2