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b=UeOFDlJjm5T2Bk/qNnZm6+wzFjUl6kO74MwQ8W+rF2ClMvhXSMCLaEnG8nEcEh0e8 7t3jJbBKOcSnpnLLB8ATQ3auwto2XRu/tV3fna6WYLFjg6mnNc3OMV1+RnFEeVjF7T khyXbrBVphkeDwDcmUhxuoS61pp9yC9fnVEaMrQYRdx6T5G1qr0pWWjH8EYUlcLD4C +FPiUQXt4AsQdgRtb/ud8Lyg9T0vWtYWx6sx9nZfO9N0VQ/aTU7otBrajsOBuHnvO5 qUoKklGcDEf8L1LUt4cgp0wKt9UgJ14tLatseFzsVuwFfErTj5oNu6dLTbFhRY/L3l yCLK1/G9ifRDQ== From: Pratyush Yadav To: DaeMyung Kang 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 In-Reply-To: <20260413165053.164338-1-charsyam@gmail.com> (DaeMyung Kang's message of "Tue, 14 Apr 2026 01:50:53 +0900") References: <20260413165053.164338-1-charsyam@gmail.com> Date: Tue, 14 Apr 2026 10:48:32 +0000 Message-ID: <2vxzik9t95rz.fsf@kernel.org> User-Agent: Gnus/5.13 (Gnus v5.13) MIME-Version: 1.0 Content-Type: text/plain X-Rspamd-Server: rspam05 X-Rspamd-Queue-Id: 228D0A000E X-Stat-Signature: srd95f9nfwepk5hhaqbcszwkesod7p8m X-Rspam-User: X-HE-Tag: 1776163715-726300 X-HE-Meta: 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 1X184UsK nykrQIQ+TniwRnd1LuJILTdy6UhTT/tSfGUBwDk2y6W17XZYsDplFzFwVXApLB0gJKNd3TaBFeZWrw5Ub8Wogc5yFbTCVrkjLQ8ZDXLMpSebCAz+O3GUfA8A1atBBn4D6HQOUVNSfprJc5mSytk68dZtXBqLjiJBQyM3d8rt0w8DN/FA3RHUeAoxfkzFMhVOMeM7y7B+JCkiOfvy5GJkfBMrI7vVs8kRWpUCDYj/f0ecFd89ancZWIE9dtz2KMvNLVhyK2I6m8nC6drM= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: 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 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