On Fri, Jan 25, 2019 at 05:45:02PM +0000, Catalin Marinas wrote:

On Mon, Jan 21, 2019 at 10:03:53AM +0200, Mike Rapoport wrote:

quoted

diff --git a/arch/arm64/mm/numa.c b/arch/arm64/mm/numa.c
index ae34e3a..2c61ea4 100644
--- a/arch/arm64/mm/numa.c
+++ b/arch/arm64/mm/numa.c

@@ -237,6 +237,10 @@ static void __init setup_node_data(int nid, u64 start_pfn, u64 end_pfn)
 		pr_info("Initmem setup node %d [<memory-less node>]\n", nid);
 
 	nd_pa = memblock_phys_alloc_try_nid(nd_size, SMP_CACHE_BYTES, nid);
+	if (!nd_pa)
+		panic("Cannot allocate %zu bytes for node %d data\n",
+		      nd_size, nid);
+
 	nd = __va(nd_pa);
 
 	/* report and initialize */

Does it mean that memblock_phys_alloc_try_nid() never returns valid
physical memory starting at 0?

Yes, it does.
memblock_find_in_range_node() that is used by all allocation methods
skips the first page [1].
 
[1] https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git/tree/mm/memblock.c#n257

-- 
Catalin

-- 
Sincerely yours,
Mike.