linux-kernel - Re: [PATCH v5 4/6] mm/huge_memory: convert VM_BUG* to VM_WARN* in __folio

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Message-ID: <5c46c13a-d558-475d-88ef-44b9ed8519f0@redhat.com>
Date: Tue, 22 Jul 2025 17:34:07 +0200
From: David Hildenbrand <david@...hat.com>
To: Zi Yan <ziy@...dia.com>, Lorenzo Stoakes <lorenzo.stoakes@...cle.com>,
 linux-mm@...ck.org
Cc: Andrew Morton <akpm@...ux-foundation.org>,
 Dan Carpenter <dan.carpenter@...aro.org>,
 Antonio Quartulli <antonio@...delbit.com>, Hugh Dickins <hughd@...gle.com>,
 Kirill Shutemov <k.shutemov@...il.com>,
 Baolin Wang <baolin.wang@...ux.alibaba.com>,
 "Liam R. Howlett" <Liam.Howlett@...cle.com>, Nico Pache <npache@...hat.com>,
 Ryan Roberts <ryan.roberts@....com>, Dev Jain <dev.jain@....com>,
 Barry Song <baohua@...nel.org>, Balbir Singh <balbirs@...dia.com>,
 Matthew Brost <matthew.brost@...el.com>, linux-kernel@...r.kernel.org
Subject: Re: [PATCH v5 4/6] mm/huge_memory: convert VM_BUG* to VM_WARN* in
 __folio_split.

On 18.07.25 20:37, Zi Yan wrote:
> These VM_BUG* can be handled gracefully without crashing kernel.
> 
> Signed-off-by: Zi Yan <ziy@...dia.com>
> Reviewed-by: Lorenzo Stoakes <lorenzo.stoakes@...cle.com>
> ---
>   mm/huge_memory.c | 10 +++++++---
>   1 file changed, 7 insertions(+), 3 deletions(-)
> 
> diff --git a/mm/huge_memory.c b/mm/huge_memory.c
> index d36f7bdaeb38..d98283164eda 100644
> --- a/mm/huge_memory.c
> +++ b/mm/huge_memory.c
> @@ -3601,8 +3601,8 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
>   	pgoff_t end;
>   	bool is_hzp;
>   
> -	VM_BUG_ON_FOLIO(!folio_test_locked(folio), folio);
> -	VM_BUG_ON_FOLIO(!folio_test_large(folio), folio);
> +	VM_WARN_ON_ONCE_FOLIO(!folio_test_locked(folio), folio);
> +	VM_WARN_ON_ONCE_FOLIO(!folio_test_large(folio), folio);
>   
>   	if (folio != page_folio(split_at) || folio != page_folio(lock_at))
>   		return -EINVAL;
> @@ -3766,7 +3766,11 @@ static int __folio_split(struct folio *folio, unsigned int new_order,
>   		}
>   
>   		if (folio_test_swapcache(folio)) {
> -			VM_BUG_ON(mapping);
> +			if (mapping) {
> +				VM_WARN_ON_ONCE_FOLIO(mapping, folio);
> +				ret = -EINVAL;
> +				goto fail;
> +			}
>   
>   			swap_cache = swap_address_space(folio->swap);
>   			xa_lock(&swap_cache->i_pages);

Acked-by: David Hildenbrand <david@...hat.com>

-- 
Cheers,

David / dhildenb