Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422739AbbD2JGU (ORCPT ); Wed, 29 Apr 2015 05:06:20 -0400 Received: from mail-oi0-f52.google.com ([209.85.218.52]:36682 "EHLO mail-oi0-f52.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031607AbbD2JGQ (ORCPT ); Wed, 29 Apr 2015 05:06:16 -0400 MIME-Version: 1.0 In-Reply-To: <1430236283-29360-2-git-send-email-shreyas@linux.vnet.ibm.com> References: <1430236283-29360-1-git-send-email-shreyas@linux.vnet.ibm.com> <1430236283-29360-2-git-send-email-shreyas@linux.vnet.ibm.com> Date: Wed, 29 Apr 2015 14:36:15 +0530 Message-ID: Subject: Re: [PATCH 2/3] tracing/mm: Don't trace mm_page_free on offline cpus From: Preeti Murthy To: "Shreyas B. Prabhu" Cc: LKML , rostedt@goodmis.org, Ingo Molnar , aneesh.kumar@linux.vnet.ibm.com Content-Type: text/plain; charset=UTF-8 Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 3263 Lines: 84 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_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 ) > -- 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/ -- 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/