From mboxrd@z Thu Jan 1 00:00:00 1970 From: Li Zhong Subject: Re: [RFC PATCH next]cpufreq: fix bad unlock balance on !CONFIG_SMP Date: Wed, 21 Aug 2013 13:53:31 +0800 Message-ID: <1377064411.2709.2.camel@ThinkPad-T5421> References: <1376975510.3788.9.camel@ThinkPad-T5421> Mime-Version: 1.0 Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 7bit Return-path: In-Reply-To: Sender: cpufreq-owner@vger.kernel.org To: Viresh Kumar Cc: linux-next list , "Rafael J. Wysocki" , Fengguang Wu , "linux-pm@vger.kernel.org" , "cpufreq@vger.kernel.org" List-Id: linux-next.vger.kernel.org On Wed, 2013-08-21 at 10:56 +0530, Viresh Kumar wrote: > On 20 August 2013 10:41, Li Zhong wrote: > > This patch tries to fix lockdep complaint attached below. > > > > It seems that we should always read acquire the cpufreq_rwsem, whether > > CONFIG_SMP is enabled or not. And CONFIG_HOTPLUG_CPU depends on > > CONFIG_SMP, so it seems we don't need CONFIG_SMP for the code enabled by > > CONFIG_HOTPLUG_CPU. > > I just figured out you haven't sent this mail to correct lists, added > them now.. Ah, sorry about that, and thank you for adding them. Thanks, Zhong > > Acked-by: Viresh Kumar > > -- > viresh > > > [ 0.504191] ===================================== > > [ 0.504627] [ BUG: bad unlock balance detected! ] > > [ 0.504627] 3.11.0-rc6-next-20130819 #1 Not tainted > > [ 0.504627] ------------------------------------- > > [ 0.504627] swapper/1 is trying to release lock (cpufreq_rwsem) at: > > [ 0.504627] [] cpufreq_add_dev+0x13a/0x3e0 > > [ 0.504627] but there are no more locks to release! > > [ 0.504627] > > [ 0.504627] other info that might help us debug this: > > [ 0.504627] 1 lock held by swapper/1: > > [ 0.504627] #0: (subsys mutex#4){+.+.+.}, at: [] subsys_interface_register+0x4f/0xe0 > > [ 0.504627] > > [ 0.504627] stack backtrace: > > [ 0.504627] CPU: 0 PID: 1 Comm: swapper Not tainted 3.11.0-rc6-next-20130819 #1 > > [ 0.504627] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007 > > [ 0.504627] ffffffff813d927a ffff88007f847c98 ffffffff814c062b ffff88007f847cc8 > > [ 0.504627] ffffffff81098bce ffff88007f847cf8 ffffffff81aadc30 ffffffff813d927a > > [ 0.504627] 00000000ffffffff ffff88007f847d68 ffffffff8109d0be 0000000000000006 > > [ 0.504627] Call Trace: > > [ 0.504627] [] ? cpufreq_add_dev+0x13a/0x3e0 > > [ 0.504627] [] dump_stack+0x19/0x1b > > [ 0.504627] [] print_unlock_imbalance_bug+0xfe/0x110 > > [ 0.504627] [] ? cpufreq_add_dev+0x13a/0x3e0 > > [ 0.504627] [] lock_release_non_nested+0x1ee/0x310 > > [ 0.504627] [] ? mark_held_locks+0xae/0x120 > > [ 0.504627] [] ? kfree+0xcb/0x1d0 > > [ 0.504627] [] ? cpufreq_policy_free+0x4a/0x60 > > [ 0.504627] [] ? cpufreq_add_dev+0x13a/0x3e0 > > [ 0.504627] [] lock_release+0xc4/0x250 > > [ 0.504627] [] up_read+0x23/0x40 > > [ 0.504627] [] cpufreq_add_dev+0x13a/0x3e0 > > [ 0.504627] [] subsys_interface_register+0x99/0xe0 > > [ 0.504627] [] ? cpufreq_gov_dbs_init+0x12/0x12 > > [ 0.504627] [] cpufreq_register_driver+0x9d/0x1d0 > > [ 0.504627] [] ? cpufreq_gov_dbs_init+0x12/0x12 > > [ 0.504627] [] acpi_cpufreq_init+0xfe/0x1f8 > > [ 0.504627] [] do_one_initcall+0xda/0x180 > > [ 0.504627] [] kernel_init_freeable+0x12c/0x1bb > > [ 0.504627] [] ? do_early_param+0x8c/0x8c > > [ 0.504627] [] ? rest_init+0x140/0x140 > > [ 0.504627] [] kernel_init+0xe/0xf0 > > [ 0.504627] [] ret_from_fork+0x7a/0xb0 > > [ 0.504627] [] ? rest_init+0x140/0x140 > > > > Signed-off-by: Li Zhong > > --- > > drivers/cpufreq/cpufreq.c | 2 +- > > 1 file changed, 1 insertion(+), 1 deletion(-) > > > > diff --git a/drivers/cpufreq/cpufreq.c b/drivers/cpufreq/cpufreq.c > > index c0ef84d..8408957 100644 > > --- a/drivers/cpufreq/cpufreq.c > > +++ b/drivers/cpufreq/cpufreq.c > > @@ -986,6 +986,7 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif, > > cpufreq_cpu_put(policy); > > return 0; > > } > > +#endif > > > > if (!down_read_trylock(&cpufreq_rwsem)) > > return 0; > > @@ -1004,7 +1005,6 @@ static int __cpufreq_add_dev(struct device *dev, struct subsys_interface *sif, > > } > > read_unlock_irqrestore(&cpufreq_driver_lock, flags); > > #endif > > -#endif > > > > if (frozen) > > /* Restore the saved policy when doing light-weight init */ > > > > >