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Date: Tue, 24 Mar 2026 19:01:44 -0700
From: Andrew Morton <akpm@linux-foundation.org>
To: Ethan Tidmore <ethantidmore06@gmail.com>
Cc: Mina Almasry <almasrymina@google.com>, Muchun Song
 <muchun.song@linux.dev>, Oscar Salvador <osalvador@suse.de>, David
 Hildenbrand <david@kernel.org>, Mike Kravetz <mike.kravetz@oracle.com>,
 David Rientjes <rientjes@google.com>, linux-mm@kvack.org,
 linux-kernel@vger.kernel.org
Subject: Re: [PATCH] hugetlb: Fix possible deadlock
Message-Id: <20260324190144.019600ff50d0734233e07bf9@linux-foundation.org>
In-Reply-To: <20260325004653.150734-1-ethantidmore06@gmail.com>
References: <20260325004653.150734-1-ethantidmore06@gmail.com>
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On Tue, 24 Mar 2026 19:46:53 -0500 Ethan Tidmore <ethantidmore06@gmail.com> 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.