CVE-2023-53614 mm/ksm: fix race with VMA iteration and mm_struct teardown

In the Linux kernel, the following vulnerability has been resolved: mm/ksm: fix race with VMA iteration and mmstruct teardown exitmmap will tear down the VMAs and maple tree with the mmaplock held in write mode. Ensure that the maple tree is still valid by checking ksmtestexit after taking the...