CVE-2026-90391

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

lib/test_hmm: fail dmirror_fault() when the mirrored mm is gone

dmirror_fault() is called from the dmirror_read() and dmirror_write()

retry loops after dmirror_do_read() or dmirror_do_write() finds a missing

device page table entry.

If the mirrored mm has already exited, mmget_not_zero() fails. The

current code returns 0 in that case, which tells the caller that faulting

succeeded even though no page was faulted and no device page table entry

was installed. The caller then retries the same address, hits -ENOENT

again, and can loop forever without making progress.

Return -EFAULT instead, so the ioctl fails when the mirrored mm is no

longer faultable.