On Wed 24-03-21 09:38:17, Mike Kravetz wrote: > On 3/24/21 1:40 AM, Michal Hocko wrote: > > On Tue 23-03-21 18:03:07, Mike Kravetz wrote: > > [...] > >> Since you brought up cgroups ... what is your opinion on lock hold time > >> in hugetlb_cgroup_css_offline? We could potentially be calling > >> hugetlb_cgroup_move_parent for every hugetlb page while holding the lock > >> with interrupts disabled. > > > > I am not familiar with hugetlb cgroup code TBH. But from a quick look > > there is not much of heavy lifting there. If we find out that this is > > really visible we can do the lock dance with cond_resched and retry with > > the iteration again. Or is there any strong reason to process the list > > in a single go? > > AFAICT, the primary reason for processing the list in a single go is > that the lock protects the list. If you drop the lock, the list can > change ... > > I have come up with a (not so pretty) way of processing the list in > batches of pages. But, I dod not want to introduce that if there is no > need. Perhaps just take a wait and see approach for now. > > I'll see if I can come up with some timing information to determine > if/when we may have an issue. I wouldn't bother at this stage. This can be done on top. -- Michal Hocko SUSE Labs
