Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422678AbbD2JHT (ORCPT ); Wed, 29 Apr 2015 05:07:19 -0400 Received: from mail-ob0-f176.google.com ([209.85.214.176]:35911 "EHLO mail-ob0-f176.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1031607AbbD2JHQ (ORCPT ); Wed, 29 Apr 2015 05:07:16 -0400 MIME-Version: 1.0 In-Reply-To: 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 14:37:15 +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" , 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 Content-Length: 3426 Lines: 85 On Wed, Apr 29, 2015 at 2:36 PM, Preeti Murthy wrote: > 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/