Re: [PATCH v4] khugepaged: fix readahead lock inversion in collapse_file()

[David Hildenbrand]

On Mon, 26 Oct 2026 23:20:13 +0800, Lance Yang wrote:
> collapse_file() can call page_cache_sync_readahead() while still holding
> source folios locked. If truncate holds mapping->invalidate_lock
> exclusively and waits for one of those folios, readahead waits for
> invalidate_lock and neither side can make progress.
> 
> We need to release those folio locks before starting readahead. On a page
> cache miss, roll back first, populate the collapse range, and retry once.
> Doing readahead after rollback avoids an extra pass when all folios are
> already present. If another miss occurs on retry, give up rather than keep
> retrying while truncate or reclaim removes folios.
> 
> [...]

Applied, thanks!

tree: mm/core.git
branch: for-next-fixes

Applied patches will appear soon in mm-next, followed by linux-next.

Please report any outstanding bugs that were missed during review, so we
can either drop the patch series or decide how to fix it up.

It is encouraged to provide Acked-bys, Reviewed-bys, and Tested-bys even
though the patches have already been applied. If possible, patch trailers
will be updated.

Note that commit hashes shown below are subject to change due to rebase,
trailer updates or similar. Further, this is not a guarantee that the
patches will go upstream. If in doubt, please check the listed branch.

[1/1] khugepaged: fix readahead lock inversion in collapse_file()
      https://git.kernel.org/mm/core/c/96995467

-- 
Cheers,

David