On Tue, 16 Jul 2024 14:13:41 +0300
Mike Rapoport [off-list ref] wrote:

From: "Mike Rapoport (Microsoft)" <rppt@kernel.org>

Move code dealing with numa_memblks from arch/x86 to mm/ and add Kconfig
options to let x86 select it in its Kconfig.

This code will be later reused by arch_numa.

No functional changes.

Signed-off-by: Mike Rapoport (Microsoft) <rppt@kernel.org>

Hi Mike,

My only real concern in here is there are a few places where
the lifted code makes changes to memblocks that are x86 only today.
I need to do some more digging to work out if those are safe
in all cases.

Jonathan

+/**
+ * numa_cleanup_meminfo - Cleanup a numa_meminfo
+ * @mi: numa_meminfo to clean up
+ *
+ * Sanitize @mi by merging and removing unnecessary memblks.  Also check for
+ * conflicts and clear unused memblks.
+ *
+ * RETURNS:
+ * 0 on success, -errno on failure.
+ */
+int __init numa_cleanup_meminfo(struct numa_meminfo *mi)
+{
+	const u64 low = 0;

Given always zero, why not just use that value inline?

+	const u64 high = PFN_PHYS(max_pfn);
+	int i, j, k;
+
+	/* first, trim all entries */
+	for (i = 0; i < mi->nr_blks; i++) {
+		struct numa_memblk *bi = &mi->blk[i];
+
+		/* move / save reserved memory ranges */
+		if (!memblock_overlaps_region(&memblock.memory,
+					bi->start, bi->end - bi->start)) {
+			numa_move_tail_memblk(&numa_reserved_meminfo, i--, mi);
+			continue;
+		}
+
+		/* make sure all non-reserved blocks are inside the limits */
+		bi->start = max(bi->start, low);
+
+		/* preserve info for non-RAM areas above 'max_pfn': */
+		if (bi->end > high) {
+			numa_add_memblk_to(bi->nid, high, bi->end,
+					   &numa_reserved_meminfo);
+			bi->end = high;
+		}
+
+		/* and there's no empty block */
+		if (bi->start >= bi->end)
+			numa_remove_memblk_from(i--, mi);
+	}
+
+	/* merge neighboring / overlapping entries */
+	for (i = 0; i < mi->nr_blks; i++) {
+		struct numa_memblk *bi = &mi->blk[i];
+
+		for (j = i + 1; j < mi->nr_blks; j++) {
+			struct numa_memblk *bj = &mi->blk[j];
+			u64 start, end;
+
+			/*
+			 * See whether there are overlapping blocks.  Whine
+			 * about but allow overlaps of the same nid.  They
+			 * will be merged below.
+			 */
+			if (bi->end > bj->start && bi->start < bj->end) {
+				if (bi->nid != bj->nid) {
+					pr_err("node %d [mem %#010Lx-%#010Lx] overlaps with node %d [mem %#010Lx-%#010Lx]\n",
+					       bi->nid, bi->start, bi->end - 1,
+					       bj->nid, bj->start, bj->end - 1);
+					return -EINVAL;
+				}
+				pr_warn("Warning: node %d [mem %#010Lx-%#010Lx] overlaps with itself [mem %#010Lx-%#010Lx]\n",
+					bi->nid, bi->start, bi->end - 1,
+					bj->start, bj->end - 1);
+			}
+
+			/*
+			 * Join together blocks on the same node, holes
+			 * between which don't overlap with memory on other
+			 * nodes.
+			 */
+			if (bi->nid != bj->nid)
+				continue;
+			start = min(bi->start, bj->start);
+			end = max(bi->end, bj->end);
+			for (k = 0; k < mi->nr_blks; k++) {
+				struct numa_memblk *bk = &mi->blk[k];
+
+				if (bi->nid == bk->nid)
+					continue;
+				if (start < bk->end && end > bk->start)
+					break;
+			}
+			if (k < mi->nr_blks)
+				continue;
+			pr_info("NUMA: Node %d [mem %#010Lx-%#010Lx] + [mem %#010Lx-%#010Lx] -> [mem %#010Lx-%#010Lx]\n",
+			       bi->nid, bi->start, bi->end - 1, bj->start,
+			       bj->end - 1, start, end - 1);
+			bi->start = start;
+			bi->end = end;
+			numa_remove_memblk_from(j--, mi);
+		}
+	}
+
+	/* clear unused ones */
+	for (i = mi->nr_blks; i < ARRAY_SIZE(mi->blk); i++) {
+		mi->blk[i].start = mi->blk[i].end = 0;
+		mi->blk[i].nid = NUMA_NO_NODE;
+	}
+
+	return 0;
+}

...

+/*
+ * Mark all currently memblock-reserved physical memory (which covers the
+ * kernel's own memory ranges) as hot-unswappable.
+ */
+static void __init numa_clear_kernel_node_hotplug(void)

This will be a change for non x86 architectures.  'should' be fine
but I'm not 100% sure.

+{
+	nodemask_t reserved_nodemask = NODE_MASK_NONE;
+	struct memblock_region *mb_region;
+	int i;
+
+	/*
+	 * We have to do some preprocessing of memblock regions, to
+	 * make them suitable for reservation.
+	 *
+	 * At this time, all memory regions reserved by memblock are
+	 * used by the kernel, but those regions are not split up
+	 * along node boundaries yet, and don't necessarily have their
+	 * node ID set yet either.
+	 *
+	 * So iterate over all memory known to the x86 architecture,

Comment needs an update at least given not x86 specific any more.

+	 * and use those ranges to set the nid in memblock.reserved.
+	 * This will split up the memblock regions along node
+	 * boundaries and will set the node IDs as well.
+	 */
+	for (i = 0; i < numa_meminfo.nr_blks; i++) {
+		struct numa_memblk *mb = numa_meminfo.blk + i;
+		int ret;
+
+		ret = memblock_set_node(mb->start, mb->end - mb->start,
+					&memblock.reserved, mb->nid);
+		WARN_ON_ONCE(ret);
+	}
+
+	/*
+	 * Now go over all reserved memblock regions, to construct a
+	 * node mask of all kernel reserved memory areas.
+	 *
+	 * [ Note, when booting with mem=nn[kMG] or in a kdump kernel,
+	 *   numa_meminfo might not include all memblock.reserved
+	 *   memory ranges, because quirks such as trim_snb_memory()
+	 *   reserve specific pages for Sandy Bridge graphics. ]
+	 */
+	for_each_reserved_mem_region(mb_region) {
+		int nid = memblock_get_region_node(mb_region);
+
+		if (nid != MAX_NUMNODES)
+			node_set(nid, reserved_nodemask);
+	}
+
+	/*
+	 * Finally, clear the MEMBLOCK_HOTPLUG flag for all memory
+	 * belonging to the reserved node mask.
+	 *
+	 * Note that this will include memory regions that reside
+	 * on nodes that contain kernel memory - entire nodes
+	 * become hot-unpluggable:
+	 */
+	for (i = 0; i < numa_meminfo.nr_blks; i++) {
+		struct numa_memblk *mb = numa_meminfo.blk + i;
+
+		if (!node_isset(mb->nid, reserved_nodemask))
+			continue;
+
+		memblock_clear_hotplug(mb->start, mb->end - mb->start);
+	}
+}