From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-oa0-f52.google.com (mail-oa0-f52.google.com [209.85.219.52]) by kanga.kvack.org (Postfix) with ESMTP id B192C6B0035 for ; Mon, 3 Feb 2014 17:57:30 -0500 (EST) Received: by mail-oa0-f52.google.com with SMTP id i4so9007225oah.11 for ; Mon, 03 Feb 2014 14:57:30 -0800 (PST) Received: from e34.co.us.ibm.com (e34.co.us.ibm.com. [32.97.110.152]) by mx.google.com with ESMTPS id tb9si10585370obc.56.2014.02.03.14.57.29 for (version=TLSv1 cipher=RC4-SHA bits=128/128); Mon, 03 Feb 2014 14:57:30 -0800 (PST) Received: from /spool/local by e34.co.us.ibm.com with IBM ESMTP SMTP Gateway: Authorized Use Only! Violators will be prosecuted for from ; Mon, 3 Feb 2014 15:57:29 -0700 Received: from b03cxnp07028.gho.boulder.ibm.com (b03cxnp07028.gho.boulder.ibm.com [9.17.130.15]) by d03dlp03.boulder.ibm.com (Postfix) with ESMTP id 7D05E19D8051 for ; Mon, 3 Feb 2014 15:57:26 -0700 (MST) Received: from d03av06.boulder.ibm.com (d03av06.boulder.ibm.com [9.17.195.245]) by b03cxnp07028.gho.boulder.ibm.com (8.13.8/8.13.8/NCO v10.0) with ESMTP id s13Mv3L94981066 for ; Mon, 3 Feb 2014 23:57:03 +0100 Received: from d03av06.boulder.ibm.com (loopback [127.0.0.1]) by d03av06.boulder.ibm.com (8.14.4/8.13.1/NCO v10.0 AVout) with ESMTP id s13N0juZ003492 for ; Mon, 3 Feb 2014 16:00:45 -0700 Date: Mon, 3 Feb 2014 14:57:25 -0800 From: "Paul E. McKenney" Subject: [PATCH] Fix lockdep false positive in add_full() Message-ID: <20140203225725.GA4069@linux.vnet.ibm.com> Reply-To: paulmck@linux.vnet.ibm.com MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline Sender: owner-linux-mm@kvack.org List-ID: To: linux-kernel@vger.kernel.org Cc: linux-mm@kvack.org, cl@linux-foundation.org, penberg@kernel.org, mpm@selenic.com, peterz@infradead.org Hello! The add_full() function currently has a lockdep_assert_held() requiring that the kmem_cache_node structure's ->list_lock be held. However, this lock is not acquired by add_full()'s caller deactivate_slab() in the full-node case unless debugging is enabled. Because full nodes are accessed only by debugging code, this state of affairs results in lockdep false-positive splats like the following: [ 43.942868] WARNING: CPU: 0 PID: 698 at /home/paulmck/public_git/linux-rcu/mm/slub.c:1007 deactivate_slab+0x509/0x720() [ 43.943016] Modules linked in: [ 43.943016] CPU: 0 PID: 698 Comm: torture_onoff Not tainted 3.14.0-rc1+ #1 [ 43.943016] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 [ 43.943016] 00000000000003ef ffff88001e3f5ba8 ffffffff818952ec 0000000000000046 [ 43.943016] 0000000000000000 ffff88001e3f5be8 ffffffff81049517 ffffea0000784e00 [ 43.943016] 0000000000000000 ffffea00007a9000 0000000000000002 0000000000000000 [ 43.943016] Call Trace: [ 43.943016] [] dump_stack+0x46/0x58 [ 43.943016] [] warn_slowpath_common+0x87/0xb0 [ 43.943016] [] warn_slowpath_null+0x15/0x20 [ 43.943016] [] deactivate_slab+0x509/0x720 [ 43.943016] [] ? slab_cpuup_callback+0x3b/0x100 [ 43.943016] [] ? slab_cpuup_callback+0xd2/0x100 [ 43.943016] [] slab_cpuup_callback+0xa4/0x100 [ 43.943016] [] notifier_call_chain+0x54/0x110 [ 43.943016] [] __raw_notifier_call_chain+0x9/0x10 [ 43.943016] [] __cpu_notify+0x1b/0x30 [ 43.943016] [] cpu_notify_nofail+0x10/0x20 [ 43.943016] [] _cpu_down+0x10d/0x2e0 [ 43.943016] [] cpu_down+0x30/0x50 [ 43.943016] [] torture_onoff+0xd3/0x3c0 [ 43.943016] [] ? torture_onoff_stats+0x90/0x90 [ 43.943016] [] kthread+0xdf/0x100 [ 43.943016] [] ? _raw_spin_unlock_irq+0x2b/0x40 [ 43.943016] [] ? flush_kthread_worker+0x130/0x130 [ 43.943016] [] ret_from_fork+0x7c/0xb0 [ 43.943016] [] ? flush_kthread_worker+0x130/0x130 This commit therefore does the lockdep check only if debuggging is enabled, thus avoiding the false positives. Signed-off-by: Paul E. McKenney Cc: linux-mm@kvack.org Cc: cl@linux-foundation.org Cc: penberg@kernel.org Cc: mpm@selenic.com diff --git a/mm/slub.c b/mm/slub.c index 7e3e0458bce4..6fff4d980b7c 100644 --- a/mm/slub.c +++ b/mm/slub.c @@ -1004,7 +1004,8 @@ static inline void slab_free_hook(struct kmem_cache *s, void *x) static void add_full(struct kmem_cache *s, struct kmem_cache_node *n, struct page *page) { - lockdep_assert_held(&n->list_lock); + if (kmem_cache_debug(s)) + lockdep_assert_held(&n->list_lock); if (!(s->flags & SLAB_STORE_USER)) return; -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org