On Wednesday, March 05, 2014 05:10:01 PM Saravana Kannan wrote: > On 03/05/2014 05:06 PM, Rafael J. Wysocki wrote: > > On Thursday, March 06, 2014 02:04:39 AM Rafael J. Wysocki wrote: > >> On Tuesday, March 04, 2014 11:44:01 AM Viresh Kumar wrote: > >>> policy->rwsem is used to lock access to all parts of code modifying struct > >>> cpufreq_policy but wasn't used on a new policy created from __cpufreq_add_dev(). > >>> > >>> Because of which if we call cpufreq_update_policy() repeatedly on one CPU and do > >>> offline/online of another CPU then we might see these crashes: > >>> > >>> Unable to handle kernel NULL pointer dereference at virtual address 00000020 > >>> pgd = c0003000 > >>> [00000020] *pgd=80000000004003, *pmd=00000000 > >>> Internal error: Oops: 206 [#1] PREEMPT SMP ARM > >>> > >>> PC is at __cpufreq_governor+0x10/0x1ac > >>> LR is at cpufreq_update_policy+0x114/0x150 > >>> > >>> ---[ end trace f23a8defea6cd706 ]--- > >>> Kernel panic - not syncing: Fatal exception > >>> CPU0: stopping > >>> CPU: 0 PID: 7136 Comm: mpdecision Tainted: G D W 3.10.0-gd727407-00074-g979ede8 #396 > >>> > >>> [<c0afe180>] (notifier_call_chain+0x40/0x68) from [<c02a23ac>] (__blocking_notifier_call_chain+0x40/0x58) > >>> [<c02a23ac>] (__blocking_notifier_call_chain+0x40/0x58) from [<c02a23d8>] (blocking_notifier_call_chain+0x14/0x1c) > >>> [<c02a23d8>] (blocking_notifier_call_chain+0x14/0x1c) from [<c0803c68>] (cpufreq_set_policy+0xd4/0x2b8) > >>> [<c0803c68>] (cpufreq_set_policy+0xd4/0x2b8) from [<c0803e7c>] (cpufreq_init_policy+0x30/0x98) > >>> [<c0803e7c>] (cpufreq_init_policy+0x30/0x98) from [<c0805a18>] (__cpufreq_add_dev.isra.17+0x4dc/0x7a4) > >>> [<c0805a18>] (__cpufreq_add_dev.isra.17+0x4dc/0x7a4) from [<c0805d38>] (cpufreq_cpu_callback+0x58/0x84) > >>> [<c0805d38>] (cpufreq_cpu_callback+0x58/0x84) from [<c0afe180>] (notifier_call_chain+0x40/0x68) > >>> [<c0afe180>] (notifier_call_chain+0x40/0x68) from [<c02812dc>] (__cpu_notify+0x28/0x44) > >>> [<c02812dc>] (__cpu_notify+0x28/0x44) from [<c0aeed90>] (_cpu_up+0xf4/0x1dc) > >>> [<c0aeed90>] (_cpu_up+0xf4/0x1dc) from [<c0aeeed4>] (cpu_up+0x5c/0x78) > >>> [<c0aeeed4>] (cpu_up+0x5c/0x78) from [<c0aec808>] (store_online+0x44/0x74) > >>> [<c0aec808>] (store_online+0x44/0x74) from [<c03a40f4>] (sysfs_write_file+0x108/0x14c) > >>> [<c03a40f4>] (sysfs_write_file+0x108/0x14c) from [<c03517d4>] (vfs_write+0xd0/0x180) > >>> [<c03517d4>] (vfs_write+0xd0/0x180) from [<c0351ca8>] (SyS_write+0x38/0x68) > >>> [<c0351ca8>] (SyS_write+0x38/0x68) from [<c0205de0>] (ret_fast_syscall+0x0/0x30) > >>> > >>> Fix these by taking locks at appropriate places in __cpufreq_add_dev() as well. > >>> > >>> Reported-by: Saravana Kannan <skannan@xxxxxxxxxxxxxx> > >>> Suggested-by: Srivatsa S. Bhat <srivatsa.bhat@xxxxxxxxxxxxxxxxxx> > >>> Signed-off-by: Viresh Kumar <viresh.kumar@xxxxxxxxxx> > >> > >> I've rebased this one on top of 3.14-rc5 and queued it up for 3.14-rc6. > >> > >> Please check the bleeding-edge branch for the result. > > > > Actually, I think I'll queue up [2-3/3] for 3.14-rc6 instead. > > > > Pretty close to having this tested and reported back. So, if you can > wait, that would be better. Should probably see an email by Fri evening PST. OK It won't hurt if they stay in bleeding-edge/linux-next till then, though. Thanks! -- I speak only for myself. Rafael J. Wysocki, Intel Open Source Technology Center. -- To unsubscribe from this list: send the line "unsubscribe cpufreq" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
