Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030446AbbD1Pvz (ORCPT ); Tue, 28 Apr 2015 11:51:55 -0400 Received: from e7.ny.us.ibm.com ([32.97.182.137]:46305 "EHLO e7.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965763AbbD1Pvv (ORCPT ); Tue, 28 Apr 2015 11:51:51 -0400 From: "Shreyas B. Prabhu" To: linux-kernel@vger.kernel.org Cc: rostedt@goodmis.org, mingo@redhat.com, aneesh.kumar@linux.vnet.ibm.com, "Shreyas B. Prabhu" Subject: [PATCH 2/3] tracing/mm: Don't trace mm_page_free on offline cpus Date: Tue, 28 Apr 2015 21:21:22 +0530 Message-Id: <1430236283-29360-2-git-send-email-shreyas@linux.vnet.ibm.com> X-Mailer: git-send-email 1.9.3 In-Reply-To: <1430236283-29360-1-git-send-email-shreyas@linux.vnet.ibm.com> References: <1430236283-29360-1-git-send-email-shreyas@linux.vnet.ibm.com> X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15042815-0037-0000-0000-0000011ECBE9 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2621 Lines: 69 Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_mm_page_free can be called on an offline cpu in this scenario caught by LOCKDEP: =============================== [ INFO: suspicious RCU usage. ] 4.1.0-rc1+ #9 Not tainted ------------------------------- include/trace/events/kmem.h:170 suspicious rcu_dereference_check() usage! other info that might help us debug this: RCU used illegally from offline CPU! rcu_scheduler_active = 1, debug_locks = 1 no locks held by swapper/1/0. stack backtrace: CPU: 1 PID: 0 Comm: swapper/1 Not tainted 4.1.0-rc1+ #9 Call Trace: [c000001fed2f7790] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable) [c000001fed2f7810] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170 [c000001fed2f78a0] [c000000000203bc4] .free_pages_prepare+0x494/0x680 [c000001fed2f7980] [c000000000207fd0] .free_hot_cold_page+0x50/0x280 [c000001fed2f7a30] [c00000000004d000] .destroy_context+0x90/0xd0 [c000001fed2f7ab0] [c0000000000bd1d8] .__mmdrop+0x58/0x160 [c000001fed2f7b40] [c0000000001068e0] .idle_task_exit+0xf0/0x100 [c000001fed2f7bc0] [c000000000066948] .pnv_smp_cpu_kill_self+0x58/0x2c0 [c000001fed2f7ca0] [c00000000003ce34] .cpu_die+0x34/0x50 [c000001fed2f7d10] [c0000000000176d0] .arch_cpu_idle_dead+0x20/0x40 [c000001fed2f7d80] [c00000000011f9a8] .cpu_startup_entry+0x708/0x7a0 [c000001fed2f7ec0] [c00000000003cb6c] .start_secondary+0x36c/0x3a0 [c000001fed2f7f90] [c000000000008b6c] start_secondary_prolog+0x10/0x14 Fix this by converting mm_page_free trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu --- include/trace/events/kmem.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index dd9e612..4abda92 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -149,12 +149,14 @@ DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, TP_CONDITION(cpu_online(smp_processor_id())) ); -TRACE_EVENT(mm_page_free, +TRACE_EVENT_CONDITION(mm_page_free, TP_PROTO(struct page *page, unsigned int order), TP_ARGS(page, order), + TP_CONDITION(cpu_online(smp_processor_id())), + TP_STRUCT__entry( __field( unsigned long, pfn ) __field( unsigned int, order ) -- 1.9.3 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/