Re: [RFC PATCH v1 1/3] locking/lockdep: Fix false warning of check_wait_context()

[Waiman Long]

On 7/11/21 10:14 AM, Xiongwei Song wrote:
> From: Xiongwei Song <sxwjean@xxxxxxxxx>
>
> We now always get a "Invalid wait context" warning with
> CONFIG_PROVE_RAW_LOCK_NESTING=y, see the full warning below:
>
> 	[    0.705900] =============================
> 	[    0.706002] [ BUG: Invalid wait context ]
> 	[    0.706180] 5.13.0+ #4 Not tainted
> 	[    0.706349] -----------------------------

I believe the purpose of CONFIG_PROVE_RAW_LOCK_NESTING is experimental 
and it is turned off by default. Turning it on can cause problem as 
shown in your lockdep splat. Limiting it to just PREEMPT_RT will defeat 
its purpose to find potential spinlock nesting problem in non-PREEMPT_RT 
kernel. The point is to fix the issue found, not hiding it from appearing.

Cheers,
Longman