On Fri, Jan 16, 2026 at 02:34:32PM -0800, Andrew Morton wrote:

On Fri, 16 Jan 2026 12:10:16 +0100 Francois Dugast [off-list ref] wrote:

quoted

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.

Without this fix, individual pages could have invalid pgmap fields and
flags (with PG_locked being notably problematic) due to prior different
order allocations, which can, and will, result in kernel crashes.

Is it OK to leave 6.18.x without this fixed?

I think 6.18.x is fine, the offending patch + large device pages is
going into 6.19, right?

Matt