Linux 7.4 Begins Employing New "Core MM" Tree

Core memory management patches to the Linux kernel have typically been routed to mainline via Andrew Morton's "MM" branch, which is where also a variety of broader memory management related patches are also queued like all the ongoing work to DAMON/DAMOS. Kernel maintainers have now agreed to a new "Core MM" tree as the home for all of the core memory management changes moving forward. At this year's Linux Maintainers Summit they agreed to move forward with a new core MM tree for lightening the load on Andrew Morton's MM tree. David Hildenbrand of Arm sent out the inaugural pull request of the Core MM code for Linux 7.4. Hildenbrand explained in the pull request: "As discussed at the Maintainer Summit, this is the first pull request from the new core MM tree. I'm a bit late due to travel. This cycle was primarily used to set up the core MM tree, move some smaller MM components into it, and establish the MM integration workflow for linux-next. For 7.4, MM updates will reach you through the slab, memblock, Andrew's MM, and my core MM trees. For the next cycle (7.5), we plan to route fewer patches through Andrew's tree and start merging the MM component trees (memblock, slab, core) into the new MM integration tree for upstreaming. In subsequent cycles, we'll gradually move more components from Andrew's MM tree into existing or new MM component trees, with the eventual goal of having a single MM integration tree for you to pull from." This pull request begins laying out that new Core MM workflow while bringing some initial patches around Get User-Pages and Memory Hotplug code.