From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758196AbcIMJuf (ORCPT ); Tue, 13 Sep 2016 05:50:35 -0400 Received: from LGEAMRELO13.lge.com ([156.147.23.53]:48138 "EHLO lgeamrelo13.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1757514AbcIMJsM (ORCPT ); Tue, 13 Sep 2016 05:48:12 -0400 X-Original-SENDERIP: 156.147.1.127 X-Original-MAILFROM: byungchul.park@lge.com X-Original-SENDERIP: 10.177.222.33 X-Original-MAILFROM: byungchul.park@lge.com From: Byungchul Park To: peterz@infradead.org, mingo@kernel.org Cc: tglx@linutronix.de, walken@google.com, boqun.feng@gmail.com, kirill@shutemov.name, linux-kernel@vger.kernel.org, linux-mm@kvack.org, iamjoonsoo.kim@lge.com, akpm@linux-foundation.org, npiggin@gmail.com Subject: [PATCH v3 09/15] lockdep: Make print_circular_bug() crosslock-aware Date: Tue, 13 Sep 2016 18:45:08 +0900 Message-Id: <1473759914-17003-10-git-send-email-byungchul.park@lge.com> X-Mailer: git-send-email 1.9.1 In-Reply-To: <1473759914-17003-1-git-send-email-byungchul.park@lge.com> References: <1473759914-17003-1-git-send-email-byungchul.park@lge.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Friends of print_circular_bug() reporting circular bug assumes that target hlock is owned by the current. However, in crossrelease feature, target hlock can be owned by any context. In this case, the circular bug is caused by target hlock which cannot be released since its dependent lock cannot be released. So the report format needs to be changed to be aware of this. Signed-off-by: Byungchul Park --- kernel/locking/lockdep.c | 56 +++++++++++++++++++++++++++++++++--------------- 1 file changed, 39 insertions(+), 17 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index fbd07ee..cb1a600 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -1126,22 +1126,41 @@ print_circular_lock_scenario(struct held_lock *src, printk("\n\n"); } - printk(" Possible unsafe locking scenario:\n\n"); - printk(" CPU0 CPU1\n"); - printk(" ---- ----\n"); - printk(" lock("); - __print_lock_name(target); - printk(");\n"); - printk(" lock("); - __print_lock_name(parent); - printk(");\n"); - printk(" lock("); - __print_lock_name(target); - printk(");\n"); - printk(" lock("); - __print_lock_name(source); - printk(");\n"); - printk("\n *** DEADLOCK ***\n\n"); + if (cross_class(target)) { + printk(" Possible unsafe locking scenario by crosslock:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(parent); + printk(");\n"); + printk(" lock("); + __print_lock_name(target); + printk(");\n"); + printk(" lock("); + __print_lock_name(source); + printk(");\n"); + printk(" unlock("); + __print_lock_name(target); + printk(");\n"); + printk("\n *** DEADLOCK ***\n\n"); + } else { + printk(" Possible unsafe locking scenario:\n\n"); + printk(" CPU0 CPU1\n"); + printk(" ---- ----\n"); + printk(" lock("); + __print_lock_name(target); + printk(");\n"); + printk(" lock("); + __print_lock_name(parent); + printk(");\n"); + printk(" lock("); + __print_lock_name(target); + printk(");\n"); + printk(" lock("); + __print_lock_name(source); + printk(");\n"); + printk("\n *** DEADLOCK ***\n\n"); + } } /* @@ -1166,7 +1185,10 @@ print_circular_bug_header(struct lock_list *entry, unsigned int depth, printk("%s/%d is trying to acquire lock:\n", curr->comm, task_pid_nr(curr)); print_lock(check_src); - printk("\nbut task is already holding lock:\n"); + if (cross_class(hlock_class(check_tgt))) + printk("\nbut now in the release context of lock:\n"); + else + printk("\nbut task is already holding lock:\n"); print_lock(check_tgt); printk("\nwhich lock already depends on the new lock.\n\n"); printk("\nthe existing dependency chain (in reverse order) is:\n"); -- 1.9.1