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

Andrew Morton
2021-11-05T20:44:46Z

From: David Hildenbrand <david@redhat.com>
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/20211004093605.5830-1-david@redhat.com
Link: https://lkml.kernel.org/r/20211004093605.5830-2-david@redhat.com
Signed-off-by: David Hildenbrand <david@redhat.com>
Cc: Mike Rapoport <rppt@kernel.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Oscar Salvador <osalvador@suse.de>
Cc: Jianyong Wu <Jianyong.Wu@arm.com>
Cc: "Aneesh Kumar K . V" <aneesh.kumar@linux.ibm.com>
Cc: Vineet Gupta <vgupta@kernel.org>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Huacai Chen <chenhuacai@kernel.org>
Cc: Jiaxun Yang <jiaxun.yang@flygoat.com>
Cc: Thomas Bogendoerfer <tsbogend@alpha.franken.de>
Cc: Heiko Carstens <hca@linux.ibm.com>
Cc: Vasily Gorbik <gor@linux.ibm.com>
Cc: Christian Borntraeger <borntraeger@de.ibm.com>
Cc: Eric Biederman <ebiederm@xmission.com>
Cc: Arnd Bergmann <arnd@arndb.de>
Cc: Shahab Vahedi <shahab@synopsys.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

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

--- 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;
}
_