On 1/12/21 12:12 AM, Jann Horn wrote: > At first I thought that this wasn't a significant issue because SLUB > has a reclaim path that can trim the percpu partial lists; but as it > turns out, that reclaim path is not actually wired up to the page > allocator's reclaim logic. The SLUB reclaim stuff is only triggered by > (very rare) subsystem-specific calls into SLUB for specific slabs and > by sysfs entries. So in userland processes will OOM even if SLUB still > has megabytes of entirely unused pages lying around. > > It might be a good idea to figure out whether it is possible to > efficiently keep track of a more accurate count of the free objects on > percpu partial lists; and if not, maybe change the accounting to > explicitly track the number of partial pages, and use limits that are > more appropriate for that? And perhaps the page allocator reclaim path > should also occasionally rip unused pages out of the percpu partial > lists? I'm gonna send a RFC that adds a proper shrinker and thus connects this shrinking to page reclaim, as a reply to this e-mail.
