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From: Pratyush Yadav <pratyush@kernel.org>
To: DaeMyung Kang <charsyam@gmail.com>
Cc: pasha.tatashin@soleen.com,  rppt@kernel.org,
	 akpm@linux-foundation.org, pratyush@kernel.org,
	 linux-mm@kvack.org,  linux-kernel@vger.kernel.org
Subject: Re: [PATCH] mm: memfd_luo: account restored large folios correctly
Date: Tue, 14 Apr 2026 10:48:32 +0000	[thread overview]
Message-ID: <2vxzik9t95rz.fsf@kernel.org> (raw)
In-Reply-To: <20260413165053.164338-1-charsyam@gmail.com> (DaeMyung Kang's message of "Tue, 14 Apr 2026 01:50:53 +0900")

Hi DaeMyung,

On Tue, Apr 14 2026, DaeMyung Kang wrote:

> memfd_luo_retrieve_folios() always passes 1 to
> shmem_inode_acct_blocks() and shmem_recalc_inode(), even when the
> restored folio spans multiple pages.
>
> That mismatches the normal shmem path: shmem_add_to_page_cache()
> accounts the folio in mapping->nrpages using folio_nr_pages(folio),
> and shmem_alloc_and_add_folio() passes the same page count to
> shmem_inode_acct_blocks() and shmem_recalc_inode().
>
> As a result, restored large folios are under-accounted in shmem inode
> and block accounting.
>
> Use folio_nr_pages(folio) here as well.
>
> Fixes: b3749f174d68 ("mm: memfd_luo: allow preserving memfd")
> Signed-off-by: DaeMyung Kang <charsyam@gmail.com>

Thanks for the patch. This bug is already fixed by this patch [0].

[0] https://lore.kernel.org/linux-mm/20260326084727.118437-2-duanchenghao@kylinos.cn/

[...]

-- 
Regards,
Pratyush Yadav


      reply	other threads:[~2026-04-14 10:48 UTC|newest]

Thread overview: 2+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2026-04-13 16:50 [PATCH] mm: memfd_luo: account restored large folios correctly DaeMyung Kang
2026-04-14 10:48 ` Pratyush Yadav [this message]

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