On Mon, Jun 08, 2026 at 03:13:56PM +0200, Maarten Lankhorst wrote: > Hey, > > On 6/8/26 14:42, Maxime Ripard wrote: > > 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 > > > I see this as an acked-by? > > I'll commit this patch to drm-misc-next if so. > > Fortunately it may not even break those scripts in the typical case > where only 1 region is registered, eg the most common laptop/desktop > case.
Natalie had a bunch of comments afaik, so I was expecting a v2, but if you intend to merge it as is, you can add it if you want. Maxime
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