mm/vmscan: remove redundant !mem_cgroup_online() checks

On Tue, Oct 27, 2026 at 06:06:05PM -0700, T.J. Mercier wrote: > Since commit f1cf8d2f36dc (“mm: memcontrol: eliminate the problem of > dying memory cgroup for LRU folios”) and commit 0e0ac326c511 (“me