linux-kernel - Re: [PATCH 1/1] mm/rmap: add CONFIG_MM_ID guard for folio_test_large_maybe_mapped

lists.openwall.net		lists / announce owl-users owl-dev john-users john-dev passwdqc-users yescrypt popa3d-users / oss-security kernel-hardening musl sabotage tlsify passwords / crypt-dev xvendor / Bugtraq Full-Disclosure linux-kernel linux-netdev linux-ext4 linux-hardening linux-cve-announce PHC
Open Source and information security mailing list archives

Hash Suite: Windows password security audit tool. GUI, reports in PDF.

[<prev] [next>] [<thread-prev] [thread-next>] [day] [month] [year] [list]

Message-ID: <a825b3c3-55f7-4d90-a318-e20acf55e0cd@redhat.com>
Date: Thu, 17 Apr 2025 14:56:15 +0200
From: David Hildenbrand <david@...hat.com>
To: Lance Yang <ioworker0@...il.com>, akpm@...ux-foundation.org
Cc: linux-mm@...ck.org, linux-kernel@...r.kernel.org,
 Mingzhe Yang <mingzhe.yang@...com>
Subject: Re: [PATCH 1/1] mm/rmap: add CONFIG_MM_ID guard for
 folio_test_large_maybe_mapped_shared()

On 17.04.25 14:49, Lance Yang wrote:
> Add a compile-time check to make sure folio_test_large_maybe_mapped_shared()
> is only used with CONFIG_MM_ID enabled, as it directly accesses the _mm_ids
> field that only works under CONFIG_MM_ID.
> 
> Suggested-by: David Hildenbrand <david@...hat.com>
> Signed-off-by: Mingzhe Yang <mingzhe.yang@...com>

^ should that be here?

> Signed-off-by: Lance Yang <ioworker0@...il.com>
> ---
>   include/linux/page-flags.h | 2 ++
>   1 file changed, 2 insertions(+)
> 
> diff --git a/include/linux/page-flags.h b/include/linux/page-flags.h
> index d3909cb1e576..6bd9b9043976 100644
> --- a/include/linux/page-flags.h
> +++ b/include/linux/page-flags.h
> @@ -1232,6 +1232,8 @@ static inline int folio_has_private(const struct folio *folio)
>   
>   static inline bool folio_test_large_maybe_mapped_shared(const struct folio *folio)
>   {
> +	/* This function should never be called without CONFIG_MM_ID enabled. */
> +	BUILD_BUG_ON(!IS_ENABLED(CONFIG_MM_ID));
>   	return test_bit(FOLIO_MM_IDS_SHARED_BITNUM, &folio->_mm_ids);
>   }
>   #undef PF_ANY

That should work. I can throw this into a cross-compile setup later if I 
get to it.

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

-- 
Cheers,

David / dhildenb