[192/262] mm/memory_hotplug: handle memblock_add_node() failures in add_memory_resource()

Commit Message

Andrew Morton Nov. 5, 2021, 8:44 p.m. UTC

From: David Hildenbrand <[e-mail]>
Subject: mm/memory_hotplug: handle memblock_add_node() failures in add_memory_resource()

Patch series "mm/memory_hotplug: full support for add_memory_driver_managed() with CONFIG_ARCH_KEEP_MEMBLOCK", v2.

Architectures that require CONFIG_ARCH_KEEP_MEMBLOCK=y, such as arm64,
don't cleanly support add_memory_driver_managed() yet.  Most prominently,
kexec_file can still end up placing kexec images on such driver-managed
memory, resulting in undesired behavior, for example, having kexec images
located on memory not part of the firmware-provided memory map.

Teaching kexec to not place images on driver-managed memory is especially
relevant for virtio-mem.  Details can be found in commit 7b7b27214bba
("mm/memory_hotplug: introduce add_memory_driver_managed()").

Extend memblock with a new flag and set it from memory hotplug code when
applicable.  This is required to fully support virtio-mem on arm64, making
also kexec_file behave like on x86-64.


This patch (of 2):

If memblock_add_node() fails, we're most probably running out of memory. 
While this is unlikely to happen, it can happen and having memory added
without a memblock can be problematic for architectures that use memblock
to detect valid memory.  Let's fail in a nice way instead of silently
ignoring the error.

Link: https://lkml.kernel.org/r/[e-mail]
Link: https://lkml.kernel.org/r/[e-mail]
Signed-off-by: David Hildenbrand <[e-mail]>
Cc: Mike Rapoport <[e-mail]>
Cc: Michal Hocko <[e-mail]>
Cc: Oscar Salvador <[e-mail]>
Cc: Jianyong Wu <[e-mail]>
Cc: "Aneesh Kumar K . V" <[e-mail]>
Cc: Vineet Gupta <[e-mail]>
Cc: Geert Uytterhoeven <[e-mail]>
Cc: Huacai Chen <[e-mail]>
Cc: Jiaxun Yang <[e-mail]>
Cc: Thomas Bogendoerfer <[e-mail]>
Cc: Heiko Carstens <[e-mail]>
Cc: Vasily Gorbik <[e-mail]>
Cc: Christian Borntraeger <[e-mail]>
Cc: Eric Biederman <[e-mail]>
Cc: Arnd Bergmann <[e-mail]>
Cc: Shahab Vahedi <[e-mail]>
Signed-off-by: Andrew Morton <[e-mail]>
---

 mm/memory_hotplug.c |    8 ++++++--
 1 file changed, 6 insertions(+), 2 deletions(-)

Patch

--- a/mm/memory_hotplug.c~mm-memory_hotplug-handle-memblock_add_node-failures-in-add_memory_resource
+++ a/mm/memory_hotplug.c
@@ -1369,8 +1369,11 @@  int __ref add_memory_resource(int nid, s
 
 	mem_hotplug_begin();
 
-	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
-		memblock_add_node(start, size, nid);
+	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK)) {
+		ret = memblock_add_node(start, size, nid);
+		if (ret)
+			goto error_mem_hotplug_end;
+	}
 
 	ret = __try_online_node(nid, false);
 	if (ret < 0)
@@ -1443,6 +1446,7 @@  error:
 		rollback_node_hotadd(nid);
 	if (IS_ENABLED(CONFIG_ARCH_KEEP_MEMBLOCK))
 		memblock_remove(start, size);
+error_mem_hotplug_end:
 	mem_hotplug_done();
 	return ret;
 }