Re: pmu_dev_alloc; warning at at kernel/locking/lockdep.c:3002 lockdep_init_map

Tejun Heo
2015-05-07T16:25:28Z

Hello,

On Thu, May 07, 2015 at 04:05:57PM +0200, Peter Zijlstra wrote:
> On Thu, May 07, 2015 at 02:54:00PM +0100, Tvrtko Ursulin wrote:
> >
> > Hi,
> >
> > 4.1.0-rc2 spews the below warning and disables lockdep for me at boot.
> >
> > Any ideas?
> >
> > May 7 11:58:20 skl kernel: [ 6.066696] futex hash table entries: 1024 (order: 5, 131072 bytes)
> > May 7 11:58:20 skl kernel: [ 6.075774] BUG: key ffff88014973b850 not in .data!
...
> > May 7 11:58:20 skl kernel: [ 6.188202] [<ffffffff811dc06a>] __kernfs_create_file+0x7a/0xf0
> > May 7 11:58:20 skl kernel: [ 6.195069] [<ffffffff811dcb4e>] sysfs_add_file_mode_ns+0x16e/0x1b0
> > May 7 11:58:20 skl kernel: [ 6.202346] [<ffffffff811dd92a>] internal_create_group+0x19a/0x280
> > May 7 11:58:20 skl kernel: [ 6.209515] [<ffffffff811dda43>] sysfs_create_group+0x13/0x20
> > May 7 11:58:20 skl kernel: [ 6.216185] [<ffffffff811dda88>] sysfs_create_groups+0x38/0x90
> > May 7 11:58:20 skl kernel: [ 6.222958] [<ffffffff8145c3d6>] device_add+0x276/0x5d0
> > May 7 11:58:20 skl kernel: [ 6.229040] [<ffffffff8110a80b>] pmu_dev_alloc+0x8b/0xd0
> > May 7 11:58:20 skl kernel: [ 6.242184] [<ffffffff81d44cd9>] perf_event_sysfs_init+0x46/0x95
> > May 7 11:58:20 skl kernel: [ 6.256118] [<ffffffff81000352>] do_one_initcall+0x122/0x1f0
> > May 7 11:58:20 skl kernel: [ 6.268980] [<ffffffff81d27126>] kernel_init_freeable+0x106/0x19a
> > May 7 11:58:20 skl kernel: [ 6.288120] [<ffffffff8161a38e>] kernel_init+0xe/0xf0
> > May 7 11:58:20 skl kernel: [ 6.294004] [<ffffffff81629e92>] ret_from_fork+0x42/0x70
> > May 7 11:58:20 skl kernel: [ 6.306367] ---[ end trace 98f2b03275198a56 ]---
> > May 7 11:58:20 skl kernel: [ 6.311703] BUG: key ffff88014973b888 not in .data!
> > May 7 11:58:20 skl kernel: [ 6.317300] BUG: key ffff88014973b8c0 not in .data!
> > May 7 11:58:20 skl kernel: [ 6.322895] BUG: key ffff88014973b8f8 not in .data!
> > May 7 11:58:20 skl kernel: [ 6.329549] HugeTLB registered 2 MB page size, pre-allocated 0 pages
>
> That's in sysfs magic mushroom land, lets Cc people who know about this.

sysfs by default uses lockdep key embedded in attrs. It looks like
somebody is making on-heap copies of attrs and using them as the group
attrs. What's the offending pmu type?

Thanks.

--
tejun