On Thu 31-05-18 15:01:33, Minchan Kim wrote: > On Wed, May 30, 2018 at 11:14:33AM -0700, Shakeel Butt wrote: > > On Tue, May 29, 2018 at 1:31 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > > On Mon 28-05-18 10:23:07, Shakeel Butt wrote: > > >> On Mon, May 28, 2018 at 2:11 AM, Michal Hocko <mhocko@xxxxxxxxxx> wrote: > > >> Though is there a precedence where the broken feature is not fixed > > >> because an alternative is available? > > > > > > Well, I can see how breaking GFP_NOFAIL semantic is problematic, on the > > > other hand we keep saying that kmem accounting in v1 is hard usable and > > > strongly discourage people from using it. Sure we can add the code which > > > handles _this_ particular case but that wouldn't make the whole thing > > > more usable I strongly suspect. Maybe I am wrong and you can provide > > > some specific examples. Is GFP_NOFAIL that common to matter? > > > > > > In any case we should balance between the code maintainability here. > > > Adding more cruft into the allocator path is not free. > > > > > > > We do not use kmem limits internally and this is something I found > > through code inspection. If this patch is increasing the cost of code > > maintainability I am fine with dropping it but at least there should a > > comment saying that kmem limits are broken and no need fix. > > I agree. > > Even, I didn't know kmem is strongly discouraged until now. Then, > why is it enabled by default on cgroup v1? You have to set a non-zero limit to make it active IIRC. The code is compiled in because v2 enables it by default. > Let's turn if off with comment "It's broken so do not use/fix. Instead, > please move to cgroup v2". -- Michal Hocko SUSE Labs
