Re: [PATCH] rcu-tasks: Use pr_debug() for callback contend/collapse messages

[Breno Leitao]

On Tue, Nov 10, 2026 at 09:35:51PM -0800, Song Liu wrote:
> Commit 5de907d24919 ("rcu-tasks: Disable callback contend/collapse
> messages by default") added the rcupdate.rcu_task_collapse_debug module
> parameter to gate the three pr_info() messages that report RCU Tasks
> switching between CPU-0 and per-CPU callback queuing.
> 
> The kernel already has a mechanism for debug-only messages that are off
> by default: pr_debug().  Use pr_debug() for these messages, and remove
> the rcu_task_collapse_debug module parameter, its documentation, and
> its boot-time announcement.
> 
> The messages stay off by default.  On CONFIG_DYNAMIC_DEBUG=y kernels,
> they can be enabled at boot with:
> 
>   dyndbg="file kernel/rcu/tasks.h +p"
> 
> or at runtime with:
> 
>   echo 'file kernel/rcu/tasks.h +p' > /proc/dynamic_debug/control
> 
> Assisted-by: Claude:claude-opus-5
> Signed-off-by: Song Liu <song@xxxxxxxxxx>

Tested-by: Breno Leitao <leitao@xxxxxxxxxx>