Re: [ANNOUNCE] v5.9-rc3-rt3

[Mike Galbraith]

On Wed, 2020-09-09 at 05:12 +0200, Mike Galbraith wrote:
> On Wed, 2020-09-02 at 17:55 +0200, Sebastian Andrzej Siewior wrote:
> >
> > Known issues
> >      - It has been pointed out that due to changes to the printk code the
> >        internal buffer representation changed. This is only an issue if tools
> >        like `crash' are used to extract the printk buffer from a kernel memory
> >        image.
>
> Ouch.  While installing -rt5 on lappy via nfs, -rt5 server box exploded
> leaving nada in logs.  I have a nifty crash dump of the event, but...

I backed out 1ce98b8a0a1..463463c6fa3f so crash will work again, but
haven't as yet been able to convince box to explode.  Hohum, I'll give
it some time.

Lockdep did repeat dirtying of its diaper though, on both lappy and
desktop boxen at roughly the same uptime.

[  922.978106] BUG: MAX_LOCKDEP_CHAIN_HLOCKS too low!
[  922.978112] turning off the locking correctness validator.
[  922.978116] CPU: 2 PID: 5837 Comm: kworker/u16:0 Kdump: loaded Tainted: G S          E     5.9.0.gf4d51df-rt5-rt #3
[  922.978120] Hardware name: MEDION MS-7848/MS-7848, BIOS M7848W08.20C 09/23/2013
[  922.978127] Workqueue: writeback wb_workfn (flush-8:48)
[  922.978131] Call Trace:
[  922.978138]  dump_stack+0x77/0x9b
[  922.978143]  validate_chain+0xf60/0x1230
[  922.978147]  __lock_acquire+0x880/0xbf0
[  922.978151]  lock_acquire+0x92/0x3f0
[  922.978155]  ? rt_spin_lock_slowlock_locked+0x5d/0x2c0
[  922.978160]  _raw_spin_lock+0x2f/0x40
[  922.978163]  ? rt_spin_lock_slowlock_locked+0x5d/0x2c0
[  922.978169]  rt_spin_lock_slowlock_locked+0x5d/0x2c0
[  922.978173]  __read_rt_lock+0x97/0xc0
[  922.978194]  ext4_es_lookup_extent+0x4f/0x410 [ext4]
[  922.978205]  ext4_map_blocks+0x50/0x530 [ext4]
[  922.978209]  ? kmem_cache_alloc+0x636/0x8b0
[  922.978220]  ext4_writepages+0xa2c/0x1330 [ext4]
[  922.978228]  ? do_writepages+0x3c/0xe0
[  922.978231]  do_writepages+0x3c/0xe0
[  922.978236]  ? __writeback_single_inode+0x62/0x890
[  922.978240]  __writeback_single_inode+0x62/0x890
[  922.978244]  writeback_sb_inodes+0x217/0x580
[  922.978250]  __writeback_inodes_wb+0x5d/0xd0
[  922.978254]  wb_writeback+0x28c/0x620
[  922.978259]  ? wb_workfn+0x2bc/0x7f0
[  922.978262]  wb_workfn+0x2bc/0x7f0
[  922.978266]  ? lock_acquire+0x92/0x3f0
[  922.978270]  ? process_one_work+0x1fa/0x730
[  922.978274]  ? process_one_work+0x284/0x730
[  922.978278]  ? process_one_work+0x251/0x730
[  922.978281]  process_one_work+0x284/0x730
[  922.978285]  ? _raw_spin_lock_irq+0x16/0x50
[  922.978289]  ? process_one_work+0x730/0x730
[  922.978293]  worker_thread+0x39/0x3f0
[  922.978297]  ? process_one_work+0x730/0x730
[  922.978300]  kthread+0x171/0x190
[  922.978304]  ? kthread_park+0x90/0x90
[  922.978308]  ret_from_fork+0x1f/0x30