Merge branch 'fix-late-dma-unmap-crash-for-page-pool'

Toke Høiland-Jørgensen says:

====================
Fix late DMA unmap crash for page pool

This series fixes the late dma_unmap crash for page pool first reported
by Yonglong Liu in [0]. It is an alternative approach to the one
submitted by Yunsheng Lin, most recently in [1]. The first commit just
wraps some tests in a helper function, in preparation of the main change
in patch 2. See the commit message of patch 2 for the details.

[0] https://lore.kernel.org/8067f204-1380-4d37-8ffd-007fc6f26738@kernel.org
[1] https://lore.kernel.org/20250307092356.638242-1-linyunsheng@huawei.com

v8: https://lore.kernel.org/20250407-page-pool-track-dma-v8-0-da9500d4ba21@redhat.com
v7: https://lore.kernel.org/20250404-page-pool-track-dma-v7-0-ad34f069bc18@redhat.com
v6: https://lore.kernel.org/20250401-page-pool-track-dma-v6-0-8b83474870d4@redhat.com
v5: https://lore.kernel.org/20250328-page-pool-track-dma-v5-0-55002af683ad@redhat.com
v4: https://lore.kernel.org/20250327-page-pool-track-dma-v4-0-b380dc6706d0@redhat.com
v3: https://lore.kernel.org/20250326-page-pool-track-dma-v3-0-8e464016e0ac@redhat.com
v2: https://lore.kernel.org/20250325-page-pool-track-dma-v2-0-113ebc1946f3@redhat.com
v1: https://lore.kernel.org/20250314-page-pool-track-dma-v1-0-c212e57a74c2@redhat.com
====================

Link: https://patch.msgid.link/20250409-page-pool-track-dma-v9-0-6a9ef2e0cba8@redhat.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>