linux-kernel - Re: [PATCH] module: Remove duplicate freeing of lockdep classes

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Message-ID: <klpmi2dad7wogo3etdxlg3vt6k72tlnszaw4otbzuamz7mzjs5@fhwdyr3ciy2y>
Date: Mon, 12 Jan 2026 14:29:41 -0500
From: Aaron Tomlin <atomlin@...mlin.com>
To: Petr Pavlu <petr.pavlu@...e.com>
Cc: Luis Chamberlain <mcgrof@...nel.org>, 
	Daniel Gomez <da.gomez@...nel.org>, Sami Tolvanen <samitolvanen@...gle.com>, 
	Peter Zijlstra <peterz@...radead.org>, Ingo Molnar <mingo@...hat.com>, Will Deacon <will@...nel.org>, 
	Boqun Feng <boqun.feng@...il.com>, Waiman Long <longman@...hat.com>, Song Liu <song@...nel.org>, 
	linux-modules@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH] module: Remove duplicate freeing of lockdep classes

On Wed, Jan 07, 2026 at 01:22:57PM +0100, Petr Pavlu wrote:
> In the error path of load_module(), under the free_module label, the
> code calls lockdep_free_key_range() to release lock classes associated
> with the MOD_DATA, MOD_RODATA and MOD_RO_AFTER_INIT module regions, and
> subsequently invokes module_deallocate().
> 
> Since commit ac3b43283923 ("module: replace module_layout with
> module_memory"), the module_deallocate() function calls free_mod_mem(),
> which releases the lock classes as well and considers all module
> regions.
> 
> Attempting to free these classes twice is unnecessary. Remove the
> redundant code in load_module().
> 
> Signed-off-by: Petr Pavlu <petr.pavlu@...e.com>
> ---
>  kernel/module/main.c | 6 ------
>  1 file changed, 6 deletions(-)
> 
> diff --git a/kernel/module/main.c b/kernel/module/main.c
> index 710ee30b3bea..bcd259505c8b 100644
> --- a/kernel/module/main.c
> +++ b/kernel/module/main.c
> @@ -3544,12 +3544,6 @@ static int load_module(struct load_info *info, const char __user *uargs,
>  	mutex_unlock(&module_mutex);
>   free_module:
>  	mod_stat_bump_invalid(info, flags);
> -	/* Free lock-classes; relies on the preceding sync_rcu() */
> -	for_class_mod_mem_type(type, core_data) {
> -		lockdep_free_key_range(mod->mem[type].base,
> -				       mod->mem[type].size);
> -	}
> -
>  	module_memory_restore_rox(mod);
>  	module_deallocate(mod, info);
>   free_copy:
> 
> base-commit: 3609fa95fb0f2c1b099e69e56634edb8fc03f87c
> -- 
> 2.52.0
> 

Thank you!

Reviewed-by: Aaron Tomlin <atomlin@...mlin.com>

-- 
Aaron Tomlin