Re: [PATCH 1/2] mm: kmemleak: serialize disable-time cleanup

[Catalin Marinas <catalin.marinas@arm.com>]

On Thu, Nov 05, 2026 at 05:52:49PM +0800, Weilin Tong wrote:
> kmemleak_do_cleanup() drops scan_mutex before removing tracked objects
> without kmemleak_lock. A concurrent clear command can therefore start
> another cleanup while the background cleanup is still running.
> 
> Keep scan_mutex held until the background cleanup completes, serializing
> its lockless removals with explicit clearing and report readers.
> 
> Fixes: 2abd839aa7e6 ("kmemleak: Do not corrupt the object_list during clean-up")
> Assisted-by: LLM
> Signed-off-by: Weilin Tong <tongweilin@linux.alibaba.com>
> ---
>  mm/kmemleak.c | 3 ++-
>  1 file changed, 2 insertions(+), 1 deletion(-)
> 
> diff --git a/mm/kmemleak.c b/mm/kmemleak.c
> index 20c0eb41c..d959d11f6 100644
> --- a/mm/kmemleak.c
> +++ b/mm/kmemleak.c
> @@ -2507,12 +2507,13 @@ static void kmemleak_do_cleanup(struct work_struct *work)
>  	 * function.
>  	 */
>  	kmemleak_free_enabled = 0;
> -	mutex_unlock(&scan_mutex);
>  
> +	/* Serialize the lockless cleanup with report readers. */
>  	if (!kmemleak_found_leaks)
>  		__kmemleak_do_cleanup();
>  	else
>  		pr_info("Kmemleak disabled without freeing internal data. Reclaim the memory with \"echo clear > /sys/kernel/debug/kmemleak\".\n");
> +	mutex_unlock(&scan_mutex);
>  }

Reviewed-by: Catalin Marinas <catalin.marinas@arm.com>

-- 
Catalin