From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422726AbbD2JEL (ORCPT ); Wed, 29 Apr 2015 05:04:11 -0400 Received: from mail-ob0-f173.google.com ([209.85.214.173]:34751 "EHLO mail-ob0-f173.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422697AbbD2JEH (ORCPT ); Wed, 29 Apr 2015 05:04:07 -0400 MIME-Version: 1.0 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> Date: Wed, 29 Apr 2015 14:34:06 +0530 Message-ID: Subject: Re: [PATCH 1/3] tracing/mm: Don't trace kmem_cache_free on offline cpus From: Preeti Murthy To: "Shreyas B. Prabhu" , Paul McKenney Cc: LKML , rostedt@goodmis.org, Ingo Molnar , aneesh.kumar@linux.vnet.ibm.com, Preeti U Murthy Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Ccing Paul, On Tue, Apr 28, 2015 at 9:21 PM, Shreyas B. Prabhu wrote: > 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, Reviewed-by: Preeti U Murthy Regards Preeti U Murthy > -- > 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/