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mm/memfd_luo: remove folio from page cache when accounting fails

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In memfd_luo_retrieve_folios(), when shmem_inode_acct_blocks() fails
after successfully adding the folio to the page cache, the code jumps
to unlock_folio without removing the folio from the page cache.

While the folio eventually will be freed when the file is released by
memfd_luo_retrieve(), it is a good idea to directly remove a folio that
was not fully added to the file.  This avoids the possibility of
accounting mismatches in shmem or filemap core.

Fix by adding a remove_from_cache label that calls
filemap_remove_folio() before unlocking, matching the error handling
pattern in shmem_alloc_and_add_folio().

This issue was identified by AI review:
https://sashiko.dev/#/patchset/20260323110747.193569-1-duanchenghao@kylinos.cn

[pratyush@kernel.org: changelog alterations]
  Link: https://lore.kernel.org/2vxzzf3lfujq.fsf@kernel.org
Link: https://lore.kernel.org/20260326084727.118437-7-duanchenghao@kylinos.cn
Signed-off-by: Chenghao Duan <duanchenghao@kylinos.cn>
Reviewed-by: Pasha Tatashin <pasha.tatashin@soleen.com>
Reviewed-by: Pratyush Yadav <pratyush@kernel.org>
Cc: Haoran Jiang <jianghaoran@kylinos.cn>
Cc: Mike Rapoport (Microsoft) <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
This commit is contained in:
Chenghao Duan 2026-03-26 16:47:26 +08:00 committed by Andrew Morton
parent 3538f90ab8
commit dc44f32fde
1 changed files with 3 additions and 1 deletions
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4
mm/memfd_luo.c
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@ -461,7 +461,7 @@ static int memfd_luo_retrieve_folios(struct file *file,
if (err) {
pr_err("shmem: failed to account folio index %ld(%ld pages): %d\n",
i, npages, err);
goto unlock_folio;
goto remove_from_cache;
}
nr_added_pages += npages;
@ -474,6 +474,8 @@ static int memfd_luo_retrieve_folios(struct file *file,
return 0;
remove_from_cache:
filemap_remove_folio(folio);
unlock_folio:
folio_unlock(folio);
folio_put(folio);