sparc64: memblock resizes are not handled properly

Pavel Tatashin · davem330 · commit cd429ce2d095 · 2017-02-23T08:33:23.000-08:00
In add_node_ranges() when memblock resize happens, the iterator keeps using
the previous freed array. This bug cause hangs on machine where there are
over 128 memory blocks during boot. For example, on machines where memory
interleaving is small.
The problem is seen on T4-4 because it cant have 2T of memory, and memory
is  interleaved at 8G. So we have 2T/8G = 256 regions to set node IDs. The
starting size of regions array is 128. Thus, we have to double at least one
time (actually we have to double twice because some memory is already
reserved and thus we need more than 256 regions). We start using an
incorrect pointer to the array after the first doubling.

Signed-off-by: Pavel Tatashin &lt;pasha.tatashin@oracle.com&gt;
Signed-off-by: Babu Moger &lt;babu.moger@oracle.com&gt;
Reviewed-by: Babu Moger &lt;babu.moger@oracle.com&gt;
Signed-off-by: David S. Miller &lt;davem@davemloft.net&gt;
diff --git a/arch/sparc/mm/init_64.c b/arch/sparc/mm/init_64.c
@@ -1126,6 +1126,10 @@ int of_node_to_nid(struct device_node *dp)
 static void __init add_node_ranges(void)
 {
 	struct memblock_region *reg;
+	unsigned long prev_max;
+
+memblock_resized:
+	prev_max = memblock.memory.max;
 
 	for_each_memblock(memory, reg) {
 		unsigned long size = reg->size;
@@ -1145,6 +1149,8 @@ static void __init add_node_ranges(void)
 
 			memblock_set_node(start, this_end - start,
 					  &memblock.memory, nid);
+			if (memblock.memory.max != prev_max)
+				goto memblock_resized;
 			start = this_end;
 		}
 	}

Original file line number	Diff line number	Diff line change
`@@ -1126,6 +1126,10 @@ int of_node_to_nid(struct device_node *dp)`
`1126`	`1126`	`static void __init add_node_ranges(void)`
`1127`	`1127`	`{`
`1128`	`1128`	`struct memblock_region *reg;`
	`1129`	`+ unsigned long prev_max;`
	`1130`	`+`
	`1131`	`+memblock_resized:`
	`1132`	`+ prev_max = memblock.memory.max;`
`1129`	`1133`
`1130`	`1134`	`for_each_memblock(memory, reg) {`
`1131`	`1135`	`unsigned long size = reg->size;`
`@@ -1145,6 +1149,8 @@ static void __init add_node_ranges(void)`
`1145`	`1149`
`1146`	`1150`	`memblock_set_node(start, this_end - start,`
`1147`	`1151`	`&memblock.memory, nid);`
	`1152`	`+ if (memblock.memory.max != prev_max)`
	`1153`	`+ goto memblock_resized;`
`1148`	`1154`	`start = this_end;`
`1149`	`1155`	`}`
`1150`	`1156`	`}`