Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1030408AbbD1Pvt (ORCPT ); Tue, 28 Apr 2015 11:51:49 -0400 Received: from e18.ny.us.ibm.com ([129.33.205.208]:35573 "EHLO e18.ny.us.ibm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965763AbbD1Pvq (ORCPT ); Tue, 28 Apr 2015 11:51:46 -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 1/3] tracing/mm: Don't trace kmem_cache_free on offline cpus Date: Tue, 28 Apr 2015 21:21:21 +0530 Message-Id: <1430236283-29360-1-git-send-email-shreyas@linux.vnet.ibm.com> X-Mailer: git-send-email 1.9.3 X-TM-AS-MML: disable X-Content-Scanned: Fidelis XPS MAILER x-cbid: 15042815-0045-0000-0000-000000117F67 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2498 Lines: 68 Since tracepoints use RCU for protection, they must not be called on offline cpus. trace_kmem_cache_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:148 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: [c000001fed2f78f0] [c0000000009dee8c] .dump_stack+0x98/0xd4 (unreliable) [c000001fed2f7970] [c000000000128d88] .lockdep_rcu_suspicious+0x108/0x170 [c000001fed2f7a00] [c00000000026f924] .kmem_cache_free+0x344/0x4b0 [c000001fed2f7ab0] [c0000000000bd1cc] .__mmdrop+0x4c/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 kmem_cache_free trace point into TRACE_EVENT_CONDITION where condition is cpu_online(smp_processor_id()) Signed-off-by: Shreyas B. Prabhu Reported-by: Aneesh Kumar K.V --- include/trace/events/kmem.h | 6 ++++-- 1 file changed, 4 insertions(+), 2 deletions(-) diff --git a/include/trace/events/kmem.h b/include/trace/events/kmem.h index 81ea598..dd9e612 100644 --- a/include/trace/events/kmem.h +++ b/include/trace/events/kmem.h @@ -140,11 +140,13 @@ DEFINE_EVENT(kmem_free, kfree, TP_ARGS(call_site, ptr) ); -DEFINE_EVENT(kmem_free, kmem_cache_free, +DEFINE_EVENT_CONDITION(kmem_free, kmem_cache_free, TP_PROTO(unsigned long call_site, const void *ptr), - TP_ARGS(call_site, ptr) + TP_ARGS(call_site, ptr), + + TP_CONDITION(cpu_online(smp_processor_id())) ); TRACE_EVENT(mm_page_free, -- 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/