On Wed, 14 Jan 2026 20:19:52 +0100 Francois Dugast [off-list ref] wrote:

Reinitialize metadata for large zone device private folios in
zone_device_page_init prior to creating a higher-order zone device
private folio. This step is necessary when the folio’s order changes
dynamically between zone_device_page_init calls to avoid building a
corrupt folio. As part of the metadata reinitialization, the dev_pagemap
must be passed in from the caller because the pgmap stored in the folio
page may have been overwritten with a compound head.

Thanks.  What are the worst-case userspace-visible effects of the bug?