Re: [PATCH] hugetlb: Fix possible deadlock

[Andrew Morton]

On Tue, 24 Mar 2026 19:46:53 -0500 Ethan Tidmore <ethantidmore06@xxxxxxxxx> wrote:

> In allocate_file_region_entries() error path the function region_chg()
> returns but does not release the lock 'resv->lock'.
> 
> Release lock 'resv->lock' before returning.
> 
> ...
>
> --- a/mm/hugetlb.c
> +++ b/mm/hugetlb.c
> @@ -807,8 +807,10 @@ static long region_chg(struct resv_map *resv, long f, long t,
>  	if (*out_regions_needed == 0)
>  		*out_regions_needed = 1;
>  
> -	if (allocate_file_region_entries(resv, *out_regions_needed))
> +	if (allocate_file_region_entries(resv, *out_regions_needed)) {
> +		spin_unlock(&resv->lock);
>  		return -ENOMEM;
> +	}
>  
>  	resv->adds_in_progress += *out_regions_needed;

Thanks, but please see how allocate_file_region_entries() leaves the
lock unheld if it's going to return -ENOMEM.