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f2fs: fix folio_nr_pages() race after put in large folio invalidate

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Our v6.18 based Android system is continuely suffering livelock and bad
page stat as shown in[1] which related to broken xarray slot status. By
investigating big folio operations within f2fs, we find below races and
fix it by get the nr_pages before drop the refcount and folio_lock.

f2fs_get_read_data_folio() calls f2fs_folio_put() before
folio_nr_pages() when invalidating a large folio from the page cache.
That unlocks the folio and drops the caller reference, leaving a window
where a concurrent truncate or folio split can shrink the compound folio
or free it before the invalidate range is computed. An undersized range
then leaves split sub-folios in mapping->i_pages, which can later
interact badly with truncate and reclaim (stale xarray entries and bad
page state when folio->mapping no longer matches the mapping being
truncated).

[1]
PID: 2594     TASK: ffffff8169b81580  CPU: 7    COMMAND: "Thread-3"
 #0 [ffffffc08ef2b8a0] xas_load at ffffffe52d1f42a4
 #1 [ffffffc08ef2b900] find_get_entries at ffffffe52c185798
 #2 [ffffffc08ef2bb60] truncate_inode_pages_range at ffffffe52c19e83c
 #3 [ffffffc08ef2bbc0] truncate_inode_pages_final at ffffffe52c19ec2c
 #4 [ffffffc08ef2bc20] f2fs_evict_inode at ffffffe52c4c8400
 #5 [ffffffc08ef2bcc0] evict at ffffffe52c2de9f4
 #6 [ffffffc08ef2bd00] iput at ffffffe52c2db1b4
 #7 [ffffffc08ef2bd30] dentry_unlink_inode at ffffffe52c2d7204
 #8 [ffffffc08ef2bd50] __dentry_kill at ffffffe52c2d3dcc
 #9 [ffffffc08ef2bd80] dput at ffffffe52c2d3c3c
 #10 [ffffffc08ef2bda0] __fput at ffffffe52c2b0a7c
 #11 [ffffffc08ef2bde0] ____fput at ffffffe52c2b1034
 #12 [ffffffc08ef2bdf0] task_work_run at ffffffe52beea200
 #13 [ffffffc08ef2be20] exit_to_user_mode_loop at ffffffe52bfbc17c
 #14 [ffffffc08ef2be80] el0_svc at ffffffe52d1f8e54
 #15 [ffffffc08ef2beb0] el0t_64_sync_handler at ffffffe52d1f8d10

Cc: stable@kernel.org
Fixes: 05e65c14ea ("f2fs: support large folio for immutable non-compressed case")
Reviewed-by: Chao Yu <chao@kernel.org>
Signed-off-by: Zhaoyang Huang <zhaoyang.huang@unisoc.com>
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
This commit is contained in:
Zhaoyang Huang 2026-07-13 19:19:44 +08:00 committed by Jaegeuk Kim
parent d0a481fad5
commit 0dab71381f
1 changed files with 2 additions and 1 deletions
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3
fs/f2fs/data.c
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@ -1323,10 +1323,11 @@ struct folio *f2fs_get_read_data_folio(struct inode *inode, pgoff_t index,
if (folio_test_large(folio)) {
pgoff_t folio_index = mapping_align_index(mapping, index);
unsigned long nr_pages = folio_nr_pages(folio);
f2fs_folio_put(folio, true);
invalidate_inode_pages2_range(mapping, folio_index,
folio_index + folio_nr_pages(folio) - 1);
folio_index + nr_pages - 1);
f2fs_schedule_timeout(DEFAULT_SCHEDULE_TIMEOUT);
goto retry;
}