On Mon, Jul 29, 2024 at 12:17 PM Max Kellermann <max.kellermann@xxxxxxxxx> wrote: > BUG: kernel NULL pointer dereference, address: 0000000000000356 This is obviously NETFS_FOLIO_COPY_TO_CACHE; this looks like it was caused by 2ff1e97587f4 ("netfs: Replace PG_fscache by setting folio->private and marking dirty"). That commit uses folio_attach_private(), but fs/ceph already used folio_attach_private() for something else.