From mboxrd@z Thu Jan 1 00:00:00 1970 From: akpm@linux-foundation.org Subject: + tracing-mm-dont-trace-mm_page_free-on-offline-cpus.patch added to -mm tree Date: Tue, 12 May 2015 13:33:40 -0700 Message-ID: <555263a4.9mCS+o4VtCHuveZ9%akpm@linux-foundation.org> Reply-To: linux-kernel@vger.kernel.org Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Return-path: Received: from mail.linuxfoundation.org ([140.211.169.12]:60302 "EHLO mail.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753674AbbELUdm (ORCPT ); Tue, 12 May 2015 16:33:42 -0400 Sender: mm-commits-owner@vger.kernel.org List-Id: mm-commits@vger.kernel.org To: shreyas@linux.vnet.ibm.com, preeti@linux.vnet.ibm.com, rostedt@goodmis.org, mm-commits@vger.kernel.org The patch titled Subject: tracing/mm: don't trace mm_page_free on offline cpus has been added to the -mm tree. Its filename is tracing-mm-dont-trace-mm_page_free-on-offline-cpus.patch This patch should soon appear at http://ozlabs.org/~akpm/mmots/broken-out/tracing-mm-dont-trace-mm_page_free-on-offline-cpus.patch and later at http://ozlabs.org/~akpm/mmotm/broken-out/tracing-mm-dont-trace-mm_page_free-on-offline-cpus.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** The -mm tree is included into linux-next and is updated there every 3-4 working days ------------------------------------------------------ From: "Shreyas B. Prabhu" Subject: tracing/mm: don't trace mm_page_free on offline cpus 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 Reviewed-by: Preeti U Murthy Acked-by: Steven Rostedt Signed-off-by: Andrew Morton --- include/trace/events/kmem.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) diff -puN include/trace/events/kmem.h~tracing-mm-dont-trace-mm_page_free-on-offline-cpus include/trace/events/kmem.h --- a/include/trace/events/kmem.h~tracing-mm-dont-trace-mm_page_free-on-offline-cpus +++ a/include/trace/events/kmem.h @@ -149,12 +149,14 @@ DEFINE_EVENT_CONDITION(kmem_free, kmem_c 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 ) _ Patches currently in -mm which might be from shreyas@linux.vnet.ibm.com are tracing-mm-dont-trace-kmem_cache_free-on-offline-cpus.patch tracing-mm-dont-trace-mm_page_free-on-offline-cpus.patch tracing-mm-dont-trace-mm_page_pcpu_drain-on-offline-cpus.patch