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

From: Waiman Long
Date: Sun Jul 11 2021 - 12:43:19 EST

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.