On Fri 22-01-16 20:17:07, Balbir Singh wrote: > On Fri, 22 Jan 2016 10:11:12 +0530 > "Aneesh Kumar K.V" <aneesh.kumar@xxxxxxxxxxxxxxxxxx> wrote: > > > Hi, > > > > I would like to attend LSF/MM this year (2016). > > > > My main interest is in MM related topics although I am also interested > > in the btrfs status discussion (particularly related to subpage size block > > size topic), if we are having one. Most of my recent work in the kernel is > > related to adding ppc64 support for different MM features. My current focus > > is on adding Linux support for the new radix MMU model of Power9. > > > > Topics of interest include: > > > > * CMA allocator issues: > > (1) order zero allocation failures: > > We are observing order zero non-movable allocation failures in kernel > > with CMA configured. We don't start a reclaim because our free memory check > > does not consider free_cma. Hence the reclaim code assume we have enough free > > pages. Joonsoo Kim tried to fix this with his ZOME_CMA patches. I would > > like to discuss the challenges in getting this merged upstream. > > https://lkml.org/lkml/2015/2/12/95 (ZONE_CMA) > > > > Others needed for the discussion: > > Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> > > > > (2) CMA allocation failures due to pinned pages in the region: > > We allow only movable allocation from the CMA region to enable us > > to migrate those pages later when we get a CMA allocation request. But > > if we pin those movable pages, we will fail the migration which can result > > in CMA allocation failure. One such report can be found here. > > http://article.gmane.org/gmane.linux.kernel.mm/136738 > > > > Peter Zijlstra's VM_PINNED patch series should help in fixing the issue. I would > > like to discuss what needs to be done to get this patch series merged upstream > > https://lkml.org/lkml/2014/5/26/345 (VM_PINNED) > > > > Others needed for the discussion: > > Peter Zijlstra <peterz@xxxxxxxxxxxxx> > > +1 > > I agree CMA design is a concern. I also noticed that today all CMA pages come > from one node. On a NUMA box you'll see cross traffic going to that region - > although from kernel only text. It should be discussed at the summit and Aneesh > would be a good representative I'm not really an mm guy but CMA has been discussed already last year, and I think even the year before... Are we moving somewhere? So if this is about hashing out what blocks VM_PINNED series (I think it may be just a lack of Peter's persistence in pushing it ;) then that looks like a sensible goal. Some other CMA architecture discussions need IMHO a more concrete proposals... Honza -- Jan Kara <jack@xxxxxxxx> SUSE Labs, CR -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>