mm/cma: report base address of single range correctly

The cma_declare_contiguous_nid code was refactored by commit c009da4
("mm, cma: support multiple contiguous ranges, if requested"), so that it
could use an internal function to attempt a single range area first, and
then try a multi-range one.

However, that meant that the actual base address used for the !fixed case
(base == 0) wasn't available one level up to be printed in the
informational message, and it would always end up printing a base address
of 0 in the boot message.

Make the internal function take a phys_addr_t pointer to the base address,
so that the value is available to the caller.

[fvdl@google.com: v2]
  Link: https://lkml.kernel.org/r/20250408164000.3215690-1-fvdl@google.com
Link: https://lkml.kernel.org/r/20250407165435.2567898-1-fvdl@google.com
Fixes: c009da4 ("mm, cma: support multiple contiguous ranges, if requested")
Signed-off-by: Frank van der Linden <fvdl@google.com>
Reported-by: Geert Uytterhoeven <geert@linux-m68k.org>
Closes: https://lore.kernel.org/linux-mm/CAMuHMdVWviQ7O9yBFE3f=ev0eVb1CnsQvR6SKtEROBbM6z7g3w@mail.gmail.com/
Tested-by: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Muchun Song <muchun.song@linux.dev>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>

Author: Frank van der Linden

mm/cma.c

@@ -35,7 +35,7 @@
 struct cma cma_areas[MAX_CMA_AREAS];
 unsigned int cma_area_count;
 
-static int __init __cma_declare_contiguous_nid(phys_addr_t base,
+static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
@@ -370,7 +370,7 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
 			phys_addr_t align, unsigned int order_per_bit,
 			const char *name, struct cma **res_cma, int nid)
 {
-	phys_addr_t start, end;
+	phys_addr_t start = 0, end;
 	phys_addr_t size, sizesum, sizeleft;
 	struct cma_init_memrange *mrp, *mlp, *failed;
 	struct cma_memrange *cmrp;
@@ -384,7 +384,7 @@ int __init cma_declare_contiguous_multi(phys_addr_t total_size,
 	/*
 	 * First, try it the normal way, producing just one range.
 	 */
-	ret = __cma_declare_contiguous_nid(0, total_size, 0, align,
+	ret = __cma_declare_contiguous_nid(&start, total_size, 0, align,
 			order_per_bit, false, name, res_cma, nid);
 	if (ret != -ENOMEM)
 		goto out;
@@ -580,7 +580,7 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 {
 	int ret;
 
-	ret = __cma_declare_contiguous_nid(base, size, limit, alignment,
+	ret = __cma_declare_contiguous_nid(&base, size, limit, alignment,
 			order_per_bit, fixed, name, res_cma, nid);
 	if (ret != 0)
 		pr_err("Failed to reserve %ld MiB\n",
@@ -592,14 +592,14 @@ int __init cma_declare_contiguous_nid(phys_addr_t base,
 	return ret;
 }
 
-static int __init __cma_declare_contiguous_nid(phys_addr_t base,
+static int __init __cma_declare_contiguous_nid(phys_addr_t *basep,
 			phys_addr_t size, phys_addr_t limit,
 			phys_addr_t alignment, unsigned int order_per_bit,
 			bool fixed, const char *name, struct cma **res_cma,
 			int nid)
 {
 	phys_addr_t memblock_end = memblock_end_of_DRAM();
-	phys_addr_t highmem_start;
+	phys_addr_t highmem_start, base = *basep;
 	int ret;
 
 	/*
@@ -722,12 +722,15 @@ static int __init __cma_declare_contiguous_nid(phys_addr_t base,
 	}
 
 	ret = cma_init_reserved_mem(base, size, order_per_bit, name, res_cma);
-	if (ret)
+	if (ret) {
 		memblock_phys_free(base, size);
+		return ret;
+	}
 
 	(*res_cma)->nid = nid;
+	*basep = base;
 
-	return ret;
+	return 0;
 }
 
 static void cma_debug_show_areas(struct cma *cma)