Re: [PATCH v2 8/8] ext4: enable large folio for regular file

Theodore Ts'o
2025-06-25T13:16:39Z

It looks like this failure requires using madvise() with MADV_HWPOISON
(which requires root) and MADV_PAGEOUT, and the stack trace is in deep
in the an mm codepath:

madvise_cold_or_pageout_pte_range+0x1cac/0x2800
reclaim_pages+0x393/0x560
reclaim_folio_list+0xe2/0x4c0
shrink_folio_list+0x44f/0x3d90
unmap_poisoned_folio+0x130/0x500
try_to_unmap+0x12f/0x140
rmap_walk+0x16b/0x1f0
...

The bisected commit is the one which enables using large folios, so
while it's possible that this due to ext4 doing something not quite
right when using large folios, it's also posible that this might be a
bug in the folio/mm code paths.

Does this reproduce on other file systems, such as XFS?

- Ted