Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758474Ab3D3DRh (ORCPT ); Mon, 29 Apr 2013 23:17:37 -0400 Received: from mail-qe0-f46.google.com ([209.85.128.46]:37723 "EHLO mail-qe0-f46.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757226Ab3D3DRb (ORCPT ); Mon, 29 Apr 2013 23:17:31 -0400 From: kosaki.motohiro@gmail.com To: linux-kernel@vger.kernel.org Cc: Olivier Langlois , Martin Schwidefsky , Steven Rostedt , David Miller , Thomas Gleixner , Frederic Weisbecker , Ingo Molnar , Peter Zijlstra , "Paul E. McKenney" , a.p.zijlstra@chello.nl, paulus@samba.org, acme@ghostprotocols.net Subject: [PATCH 01/10] events: Protect access via task_subsys_state_check() Date: Mon, 29 Apr 2013 23:17:09 -0400 Message-Id: <1367291838-5490-2-git-send-email-kosaki.motohiro@gmail.com> X-Mailer: git-send-email 1.7.1 In-Reply-To: <1367291838-5490-1-git-send-email-kosaki.motohiro@gmail.com> References: <1367291838-5490-1-git-send-email-kosaki.motohiro@gmail.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 2625 Lines: 70 From: Paul E. McKenney The following RCU splat indicates lack of RCU protection: [ 953.267649] =============================== [ 953.267652] [ INFO: suspicious RCU usage. ] [ 953.267657] 3.9.0-0.rc6.git2.4.fc19.ppc64p7 #1 Not tainted [ 953.267661] ------------------------------- [ 953.267664] include/linux/cgroup.h:534 suspicious rcu_dereference_check() usage! [ 953.267669] [ 953.267669] other info that might help us debug this: [ 953.267669] [ 953.267675] [ 953.267675] rcu_scheduler_active = 1, debug_locks = 0 [ 953.267680] 1 lock held by glxgears/1289: [ 953.267683] #0: (&sig->cred_guard_mutex){+.+.+.}, at: [] .prepare_bprm_creds+0x34/0xa0 [ 953.267700] [ 953.267700] stack backtrace: [ 953.267704] Call Trace: [ 953.267709] [c0000001f0d1b6e0] [c000000000016e30] .show_stack+0x130/0x200 (unreliable) [ 953.267717] [c0000001f0d1b7b0] [c0000000001267f8] .lockdep_rcu_suspicious+0x138/0x180 [ 953.267724] [c0000001f0d1b840] [c0000000001d43a4] .perf_event_comm+0x4c4/0x690 [ 953.267731] [c0000001f0d1b950] [c00000000027f6e4] .set_task_comm+0x84/0x1f0 [ 953.267737] [c0000001f0d1b9f0] [c000000000280414] .setup_new_exec+0x94/0x220 [ 953.267744] [c0000001f0d1ba70] [c0000000002f665c] .load_elf_binary+0x58c/0x19b0 ... This commit therefore adds the required RCU read-side critical section to perf_event_comm(). Reported-by: Adam Jackson Signed-off-by: Paul E. McKenney Cc: a.p.zijlstra@chello.nl Cc: paulus@samba.org Cc: acme@ghostprotocols.net Link: http://lkml.kernel.org/r/20130419190124.GA8638@linux.vnet.ibm.com Signed-off-by: Ingo Molnar Tested-by: Gustavo Luiz Duarte --- kernel/events/core.c | 2 ++ 1 files changed, 2 insertions(+), 0 deletions(-) diff --git a/kernel/events/core.c b/kernel/events/core.c index 4d3124b..9fcb094 100644 --- a/kernel/events/core.c +++ b/kernel/events/core.c @@ -4596,6 +4596,7 @@ void perf_event_comm(struct task_struct *task) struct perf_event_context *ctx; int ctxn; + rcu_read_lock(); for_each_task_context_nr(ctxn) { ctx = task->perf_event_ctxp[ctxn]; if (!ctx) @@ -4603,6 +4604,7 @@ void perf_event_comm(struct task_struct *task) perf_event_enable_on_exec(ctx); } + rcu_read_unlock(); if (!atomic_read(&nr_comm_events)) return; -- 1.7.1 -- 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/