On Tue, Jan 24, 2023 at 04:42:43PM +1100, Alistair Popple wrote: > If too much memory in a system is pinned or locked it can lead to > problems such as performance degredation or in the worst case > out-of-memory errors as such memory cannot be moved or paged out. > > In order to prevent users without CAP_IPC_LOCK from causing these > issues the amount of memory that can be pinned is typically limited by > RLIMIT_MEMLOCK. However this is inflexible as limits can't be shared > between tasks and the enforcement of these limits is inconsistent > between in-kernel users of pinned memory such as mlock() and device > drivers which may also pin pages with pin_user_pages(). > > To allow for a single limit to be set introduce a cgroup controller > which can be used to limit the number of pages being pinned by all > tasks in the cgroup. The use case makes some sense to me but I wonder whether this'd fit a lot better in memcg rather than being its own controller.