Description: sched/membarrier: reduce the ability to hammer on sys_membarrier
References:
Notes:
 carnil> Introduced in 22e4ebb97582 ("membarrier: Provide expedited private command")
 carnil> c5f58bd58f43 ("membarrier: Provide GLOBAL_EXPEDITED command"). Vulnerable
 carnil> versions: 4.14-rc1 4.16-rc1.
Bugs:
upstream: released (6.8-rc6) [944d5fe50f3f03daacfea16300e656a1691c4a23]
6.7-upstream-stable: released (6.7.6) [c5b2063c65d05e79fad8029324581d86cfba7eea]
6.6-upstream-stable: released (6.6.18) [b6a2a9cbb67545c825ec95f06adb7ff300a2ad71]
6.1-upstream-stable: released (6.1.79) [24ec7504a08a67247fbe798d1de995208a8c128a]
5.10-upstream-stable: released (5.10.210) [db896bbe4a9c67cee377e5f6a743350d3ae4acf6]
4.19-upstream-stable: released (4.19.307) [3cd139875e9a7688b3fc715264032620812a5fa3]
sid: released (6.7.7-1)
6.1-bookworm-security: released (6.1.82-1)
5.10-bullseye-security: needed
4.19-buster-security: pending (4.19.309-1)