From mboxrd@z Thu Jan 1 00:00:00 1970 From: Sasha Levin Subject: net: rcu warnings in ip6fl_get_first Date: Thu, 07 Feb 2013 14:32:36 -0500 Message-ID: <51140154.9040901@oracle.com> Mime-Version: 1.0 Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Cc: Dave Jones , netdev@vger.kernel.org, "linux-kernel@vger.kernel.org" To: "David S. Miller" , yoshfuji@linux-ipv6.org Return-path: Sender: linux-kernel-owner@vger.kernel.org List-Id: netdev.vger.kernel.org Hi guys, I got the following while fuzzing with trinity inside a KVM tools guest: [ 51.680236] =============================== [ 51.681914] [ INFO: suspicious RCU usage. ] [ 51.683610] 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 Tainted: G W [ 51.686703] ------------------------------- [ 51.688281] net/ipv6/ip6_flowlabel.c:671 suspicious rcu_dereference_check() usage! [ 51.691345] [ 51.691345] other info that might help us debug this: [ 51.691345] [ 51.694479] [ 51.694479] rcu_scheduler_active = 1, debug_locks = 1 [ 51.697650] 2 locks held by trinity/7421: [ 51.701271] #0: (&p->lock){+.+.+.}, at: [] seq_read+0x3a/0x3d0 [ 51.704292] #1: (rcu_read_lock_bh){.+....}, at: [] ip6fl_seq_start+0x0/0xe0 [ 51.707845] [ 51.707845] stack backtrace: [ 51.709678] Pid: 7421, comm: trinity Tainted: G W 3.8.0-rc6-next-20130206-sasha-00028-g83214f7-dirty #276 [ 51.713495] Call Trace: [ 51.714370] [] lockdep_rcu_suspicious+0x10b/0x120 [ 51.716560] [] ip6fl_get_first+0x8a/0x140 [ 51.718755] [] ip6fl_seq_next+0x17/0x40 [ 51.720963] [] seq_read+0x2b1/0x3d0 [ 51.723056] [] ? seq_lseek+0x110/0x110 [ 51.725238] [] proc_reg_read+0x9c/0xd0 [ 51.727266] [] ? proc_reg_write+0xd0/0xd0 [ 51.729337] [] do_loop_readv_writev+0x4b/0x90 [ 51.731846] [] do_readv_writev+0xf6/0x1d0 [ 51.734092] [] vfs_readv+0x3e/0x60 [ 51.736015] [] sys_readv+0x50/0xd0 [ 51.737930] [] tracesys+0xe1/0xe6 This is the result of commit "ipv6 flowlabel: Convert hash list to RCU." which mixes between regular and _bh() locking. Thanks, Sasha