Description: hugetlbfs: flush TLBs correctly after huge_pmd_unshare
References:
 https://www.openwall.com/lists/oss-security/2021/11/25/1
Notes:
 carnil> For 5.16-rc1 onwards only additionally there is 13e4ad2ce8df
 carnil> ("hugetlbfs: flush before unlock on
 carnil> move_hugetlb_page_tables()") to be applied.
Bugs:
upstream: pending [a4a118f2eead1d6c49e00765de89878288d4b890]
5.10-upstream-stable: released (5.10.82) [40bc831ab5f630431010d1ff867390b07418a7ee]
4.19-upstream-stable: needed
4.9-upstream-stable: needed
sid: released (5.15.5-1)
5.10-bullseye-security: needed
4.19-buster-security: needed
4.9-stretch-security: needed