CVE-2026-46280

In the Linux kernel, the following vulnerability has been resolved:

lib: test_hmm: evict device pages on file close to avoid use-after-free

Patch series "Minor hmm_test fixes and cleanups".

Two bugfixes a cleanup for the HMM kernel selftests. These were mostly

reported by Zenghui Yu with special thanks to Lorenzo for analysing and

pointing out the problems.

This patch (of 3):

When dmirror_fops_release() is called it frees the dmirror struct but

doesn't migrate device private pages back to system memory first. This

leaves those pages with a dangling zone_device_data pointer to the freed

dmirror.

If a subsequent fault occurs on those pages (eg. during coredump) the

dmirror_devmem_fault() callback dereferences the stale pointer causing a

kernel panic. This was reported [1] when running mm/ksft_hmm.sh on arm64,

where a test failure triggered SIGABRT and the resulting coredump walked

the VMAs faulting in the stale device private pages.

Fix this by calling dmirror_device_evict_chunk() for each devmem chunk in

dmirror_fops_release() to migrate all device private pages back to system

memory before freeing the dmirror struct. The function is moved earlier

in the file to avoid a forward declaration.