On 07/23/2018 09:24 PM, Mike Kravetz wrote:
With v4.17, I can see an issue like those addressed in commits 3c605096d315
("mm/page_alloc: restrict max order of merging on isolated pageblock")
and d9dddbf55667 ("mm/page_alloc: prevent merging between isolated and
other pageblocks"). After running a CMA stress test for a while, I see:
MemTotal: 8168384 kB
MemFree: 8457232 kB
MemAvailable: 9204844 kB
If I let the test run, MemFree and MemAvailable will continue to grow.
I am certain the issue is with pageblocks of migratetype ISOLATED. If
I disable all special 'is_migrate_isolate' checks in freepage accounting,
the issue goes away. Further, I am pretty sure the issue has to do with
pageblock merging and or page orders spanning pageblocks. If I make
pageblock_order equal MAX_ORDER-1, the issue also goes away.
Just looking for suggesting in where/how to debug. I've been hacking on
this without much success.
--
Mike Kravetz
If you revert d883c6cf3b39 ("Revert "mm/cma: manage the memory of the CMA
area by using the ZONE_MOVABLE"") do you still see the issue? I thought
there was another isolation edge case which was fixed by that series.
Thanks,
Laura
