offline_pages() properly checks for memory holes and bails out.
However, we do a page_zone(pfn_to_page(start_pfn)) before calling
offline_pages() when offlining a memory block.
We should not unconditionally call page_zone(pfn_to_page(start_pfn)) on
aarch64 in offlining code, otherwise we can trigger a BUG when hitting a
memory hole:
kernel BUG at include/linux/mm.h:1383!
Internal error: Oops - BUG: 0 [#1] SMP
Modules linked in: loop processor efivarfs ip_tables x_tables ext4 mbcache jbd2 dm_mod igb nvme i2c_algo_bit mlx5_core i2c_core nvme_core firmware_class
CPU: 13 PID: 1694 Comm: ranbug Not tainted 5.12.0-next-20210524+ #4
Hardware name: MiTAC RAPTOR EV-883832-X3-0001/RAPTOR, BIOS 1.6 06/28/2020
pstate: 60000005 (nZCv daif -PAN -UAO -TCO BTYPE=--)
pc : memory_subsys_offline+0x1f8/0x250
lr : memory_subsys_offline+0x1f8/0x250
Call trace:
memory_subsys_offline+0x1f8/0x250
device_offline+0x154/0x1d8
online_store+0xa4/0x118
dev_attr_store+0x44/0x78
sysfs_kf_write+0xe8/0x138
kernfs_fop_write_iter+0x26c/0x3d0
new_sync_write+0x2bc/0x4f8
vfs_write+0x718/0xc88
ksys_write+0xf8/0x1e0
__arm64_sys_write+0x74/0xa8
invoke_syscall.constprop.0+0x78/0x1e8
do_el0_svc+0xe4/0x298
el0_svc+0x20/0x30
el0_sync_handler+0xb0/0xb8
el0_sync+0x178/0x180
Kernel panic - not syncing: Oops - BUG: Fatal exception
SMP: stopping secondary CPUs
Kernel Offset: disabled
CPU features: 0x00000251,20000846
Memory Limit: none
If nr_vmemmap_pages is set, we know that we are dealing with hotplugged
memory that doesn't have any holes. So call
page_zone(pfn_to_page(start_pfn)) only when really necessary -- when
nr_vmemmap_pages is set and we actually adjust the present pages.
Link: https://lkml.kernel.org/r/20210526075226.5572-1-david@redhat.com
Fixes: a08a2ae346 ("mm,memory_hotplug: allocate memmap from the added memory range")
Signed-off-by: David Hildenbrand <david@redhat.com>
Reported-by: Qian Cai (QUIC) <quic_qiancai@quicinc.com>
Reviewed-by: Oscar Salvador <osalvador@suse.de>
Acked-by: Michal Hocko <mhocko@suse.com>
Cc: Anshuman Khandual <anshuman.khandual@arm.com>
Cc: Mike Rapoport <rppt@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
928130532e