Description: cgroup: Use open-time creds and namespace for migration perm checks
References:
 https://lore.kernel.org/lkml/20211209214707.805617-1-tj@kernel.org/T/
 https://bugzilla.redhat.com/show_bug.cgi?id=2035652
Notes:
 carnil> Fixed as well in 5.15.14 for 5.15.y.
 bwh> At least the first commit is applicable to all branches.
Bugs:
upstream: released (5.16) [1756d7994ad85c2479af6ae5a9750b92324685af, 0d2b5955b36250a9428c832664f2079cbf723bec, e57457641613fef0d147ede8bd6a3047df588b95]
5.10-upstream-stable: released (5.10.109) [f28364fe384feffbe7d44b095ef4571285465c47, 824a950c3f1118eb06b1877c49ed1b2eca8e236d], released (5.10.111) [4665722d36ad13c6abc6b2ef3fe5150c0a92d870]
4.19-upstream-stable: released (4.19.238) [0bd407959f7d6671ba0617e2dbda3e89d8a0419f, de37e01dd20e3228b010fe5fbd3e205747481b96, 74ac12c718e7d3f7eb346ee90a4c9904a8b6b6d2]
4.9-upstream-stable: needed
sid: released (5.15.15-1)
5.10-bullseye-security: released (5.10.113-1)
4.19-buster-security: released (4.19.249-1)
4.9-stretch-security: ignored "EOL"