Re: BUG: unable to handle kernel NULL pointer dereference at 0000000000000038 !//RE: kernel BUG at kernel/locking/rtmutex.c:1027

From: Sebastian Andrzej Siewior
Date: Mon Jun 26 2017 - 10:54:48 EST


On 2017-06-26 10:24:18 [-0400], Steven Rostedt wrote:
> > CPU: 17 PID: 1738811 Comm: ip Not tainted 4.4.70-thinkcloud-nfv #1
> > Hardware name: LENOVO System x3650 M5: -[8871AC1]-/01GR174, BIOS -[TCE124M-2.10]- 06/23/2016
> > task: ffff881cda2c27c0 ti: ffff881ea0538000 task.ti: ffff881ea0538000
> > RIP: 0010:[<ffffffff810a2cb4>] [<ffffffff810a2cb4>] __try_to_take_rt_mutex+0x34/0x160
> > RSP: 0018:ffff881ea053bb50 EFLAGS: 00010082
> > RAX: 0000000000000000 RBX: ffff881f805416a8 RCX: 0000000000000000
> > RDX: ffff881ea053bb98 RSI: ffff881cda2c27c0 RDI: ffff881f805416a8
> > RBP: ffff881ea053bb60 R08: 0000000000000001 R09: 0000000000000002
> > R10: 0000000000000a01 R11: 0000000000000001 R12: ffff881cda2c27c0
> > R13: ffff881cda2c27c0 R14: 0000000000000202 R15: ffff881f6b0c27c0
> > FS: 00007f28be315740(0000) GS:ffff88205f8c0000(0000) knlGS:0000000000000000
> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
> > CR2: 0000000000000038 CR3: 0000001e9e479000 CR4: 00000000003406e0
> > DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
> > DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
> > Stack:
> > ffff881f805416a8 ffff881ea053bb98 ffff881ea053bc28 ffffffff81a8f03d
> > ffff881ea053c000 01ff881ea053bb90 ffff881cda2c27c0 ffff881f6b0c27c1
> > ffff881cda2c2eb0 0000000000000001 0000000000000000 0000000000000000
> > Call Trace:
> > [<ffffffff81a8f03d>] rt_spin_lock_slowlock+0x13d/0x390
> > [<ffffffff81a903bf>] rt_spin_lock+0x1f/0x30
> > [<ffffffff8141757f>] lockref_get_not_dead+0xf/0x50
> > [<ffffffff811e0a01>] ns_get_path+0x61/0x1d0
>
> Hmm, this is in the filesystem code. What were you doing when this
> happened?

and do you have any patches except the RT patch?

>
> > <4>Jun 24 10:01:19 node-1 kernel: [44959.446268] [<ffffffff8121eea9>] proc_ns_follow_link+0x89/0xa0
>
> Do you know what proc file it was reading?
>
> -- Steve

Sebastian