On Sat, Jun 06, 2026 at 11:44:10PM +0200, Maarten Lankhorst wrote: > Hey, > > On 6/6/26 18:31, Natalie Vock wrote: > > On 6/6/26 00:44, Eric Chanudet wrote: > >> Accept only one "region value" pair entry for the dmem.max, dmem.min, > >> dmem.low files.> > >> This changes the UAPI that otherwise accepted multiple lines for setting > >> multiple entries in one write. No existing user is known to rely on > >> writing multiple regions in a single write. > > > > Ugh, shoot. > > > > For dmem.low specifically, there already are some userspace thingies > > floating around that may write more than one region/value pairs. > > > > These thingies all depend on that one patchset for dmemcg protection that I > > should really get around to merging[1]. Since the userspace utilities > > depend on not-yet-merged patches, they sort of have to expect stuff > > changing under their belts, so I wouldn't really consider those users a > > blocker by necessity. > > > > As I see it, we could go down one of two paths: > > 1. We go ahead with the patch as proposed, and I make sure that the users I > > know of adapt. Could be a bit icky wrt. "do not break userspace" rules, but > > since the already use non-merged UAPIs in one place, you can argue that > > these users kind of have to expect breakage. > > 2. We use the old handling allowing multiple lines for dmem.min and > > dmem.low only. This preserves compatibility but uglifies the code by quite > > a bit. > > > > All things considered, I think I personally would prefer going with 1. and > > taking the patch as proposed and just having one codepath handling every > > limit file. Just highlighting this so we don't do it on accident. > > > > [1] https://patchwork.freedesktop.org/series/163183/ > > > > I prefer option 1 as well, but would like an ack from one of the core cgroup > maintainers too, > and what Maxime's opinion on this as well.
Option 1 works for me too if doable Maxime
signature.asc
Description: PGP signature
