mm: handle uninitialized numa nodes gracefully

We have had several reports [1][2][3] that page allocator blows up when an
allocation from a possible node is requested.  The underlying reason is
that NODE_DATA for the specific node is not allocated.

NUMA specific initialization is arch specific and it can vary a lot.  E.g.
x86 tries to initialize all nodes that have some cpu affinity (see
init_cpu_to_node) but this can be insufficient because the node might be
cpuless for example.

One way to address this problem would be to check for !node_online nodes
when trying to get a zonelist and silently fall back to another node.
That is unfortunately adding a branch into allocator hot path and it
doesn't handle any other potential NODE_DATA users.

This patch takes a different approach (following a lead of [3]) and it pre
allocates pgdat for all possible nodes in an arch indipendent code -
free_area_init.  All uninitialized nodes are treated as memoryless nodes.
node_state of the node is not changed because that would lead to other
side effects - e.g.  sysfs representation of such a node and from past
discussions [4] it is known that some tools might have problems digesting
that.

Newly allocated pgdat only gets a minimal initialization and the rest of
the work is expected to be done by the memory hotplug - hotadd_new_pgdat
(renamed to hotadd_init_pgdat).

generic_alloc_nodedata is changed to use the memblock allocator because
neither page nor slab allocators are available at the stage when all
pgdats are allocated.  Hotplug doesn't allocate pgdat anymore so we can
use the early boot allocator.  The only arch specific implementation is
ia64 and that is changed to use the early allocator as well.

[1] http://lkml.kernel.org/r/20211101201312.11589-1-amakhalov@vmware.com
[2] http://lkml.kernel.org/r/20211207224013.880775-1-npache@redhat.com
[3] http://lkml.kernel.org/r/20190114082416.30939-1-mhocko@kernel.org
[4] http://lkml.kernel.org/r/20200428093836.27190-1-srikar@linux.vnet.ibm.com

[akpm@linux-foundation.org: replace comment, per Mike]

Link: https://lkml.kernel.org/r/Yfe7RBeLCijnWBON@dhcp22.suse.cz
Reported-by: Alexey Makhalov <amakhalov@vmware.com>
Tested-by: Alexey Makhalov <amakhalov@vmware.com>
Reported-by: Nico Pache <npache@redhat.com>
Acked-by: Rafael Aquini <raquini@redhat.com>
Tested-by: Rafael Aquini <raquini@redhat.com>
Acked-by: David Hildenbrand <david@redhat.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Mike Rapoport <rppt@linux.ibm.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
Cc: Christoph Lameter <cl@linux.com>
Cc: Dennis Zhou <dennis@kernel.org>
Cc: Eric Dumazet <eric.dumazet@gmail.com>
Cc: Tejun Heo <tj@kernel.org>
Cc: Wei Yang <richard.weiyang@gmail.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 9 insertions, 12 deletions

diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c
index 0139b77c51d5..11f39d0e76ec 100644
--- a/mm/memory_hotplug.c
+++ b/mm/memory_hotplug.c
@@ -1162,19 +1162,21 @@ static void reset_node_present_pages(pg_data_t *pgdat)
 }
 
 /* we are OK calling __meminit stuff here - we have CONFIG_MEMORY_HOTPLUG */
-static pg_data_t __ref *hotadd_new_pgdat(int nid)
+static pg_data_t __ref *hotadd_init_pgdat(int nid)
 {
 	struct pglist_data *pgdat;
 
 	pgdat = NODE_DATA(nid);
-	if (!pgdat) {
-		pgdat = arch_alloc_nodedata(nid);
-		if (!pgdat)
-			return NULL;
 
+	/*
+	 * NODE_DATA is preallocated (free_area_init) but its internal
+	 * state is not allocated completely. Add missing pieces.
+	 * Completely offline nodes stay around and they just need
+	 * reintialization.
+	 */
+	if (pgdat->per_cpu_nodestats == &boot_nodestats) {
 		pgdat->per_cpu_nodestats =
 			alloc_percpu(struct per_cpu_nodestat);
-		arch_refresh_nodedata(nid, pgdat);
 	} else {
 		int cpu;
 		/*
@@ -1193,8 +1195,6 @@ static pg_data_t __ref *hotadd_new_pgdat(int nid)
 		}
 	}
 
-	/* we can use NODE_DATA(nid) from here */
-	pgdat->node_id = nid;
 	pgdat->node_start_pfn = 0;
 
 	/* init node's zones as empty zones, we don't have any present pages.*/
@@ -1246,7 +1246,7 @@ static int __try_online_node(int nid, bool set_node_online)
 	if (node_online(nid))
 		return 0;
 
-	pgdat = hotadd_new_pgdat(nid);
+	pgdat = hotadd_init_pgdat(nid);
 	if (!pgdat) {
 		pr_err("Cannot online node %d due to NULL pgdat\n", nid);
 		ret = -ENOMEM;
@@ -1445,9 +1445,6 @@ int __ref add_memory_resource(int nid, struct resource *res, mhp_t mhp_flags)
 
 	return ret;
 error:
-	/* rollback pgdat allocation and others */
-	if (new_node)
-		rollback_node_hotadd(nid);
 	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
 		memblock_remove(start, size);
 error_mem_hotplug_end: