Re: Blockdev 6.13-rc lockdep splat regressions

[Ming Lei <ming.lei@redhat.com>]

On Fri, Jan 10, 2025 at 11:12:58AM +0100, Thomas Hellström wrote:
> Ming, Others
> 
> On 6.13-rc6 I'm seeing a couple of lockdep splats which appear
> introduced by the commit
> 
> f1be1788a32e ("block: model freeze & enter queue as lock for supporting
> lockdep")

The freeze lock connects all kinds of sub-system locks, that is why
we see lots of warnings after the commit is merged.

...

> #1
> [  399.006581] ======================================================
> [  399.006756] WARNING: possible circular locking dependency detected
> [  399.006767] 6.12.0-rc4+ #1 Tainted: G     U           N
> [  399.006776] ------------------------------------------------------
> [  399.006801] kswapd0/116 is trying to acquire lock:
> [  399.006810] ffff9a67a1284a28 (&q->q_usage_counter(io)){++++}-{0:0},
> at: __submit_bio+0xf0/0x1c0
> [  399.006845] 
>                but task is already holding lock:
> [  399.006856] ffffffff8a65bf00 (fs_reclaim){+.+.}-{0:0}, at:
> balance_pgdat+0xe2/0xa20
> [  399.006874] 

The above one is solved in for-6.14/block of block tree:

	block: track queue dying state automatically for modeling queue freeze lockdep

> 
> #2:
> [   81.960829] ======================================================
> [   81.961010] WARNING: possible circular locking dependency detected
> [   81.961048] 6.12.0-rc4+ #3 Tainted: G     U            

...

>                -> #3 (&q->limits_lock){+.+.}-{4:4}:
> [   81.967815]        __mutex_lock+0xad/0xb80
> [   81.968133]        nvme_update_ns_info_block+0x128/0x870 [nvme_core]
> [   81.968456]        nvme_update_ns_info+0x41/0x220 [nvme_core]
> [   81.968774]        nvme_alloc_ns+0x8a6/0xb50 [nvme_core]
> [   81.969090]        nvme_scan_ns+0x251/0x330 [nvme_core]
> [   81.969401]        async_run_entry_fn+0x31/0x130
> [   81.969703]        process_one_work+0x21a/0x590
> [   81.970004]        worker_thread+0x1c3/0x3b0
> [   81.970302]        kthread+0xd2/0x100
> [   81.970603]        ret_from_fork+0x31/0x50
> [   81.970901]        ret_from_fork_asm+0x1a/0x30
> [   81.971195] 
>                -> #2 (&q->q_usage_counter(io)){++++}-{0:0}:

The above dependency is killed by Christoph's patch.


Thanks,
Ming