When testing the remove_memory path of dax pmem, there will be a panic with call trace: try_remove_memory+0x84/0x170 remove_memory+0x38/0x58 dev_dax_kmem_remove+0x3c/0x84 [kmem] device_release_driver_internal+0xfc/0x1c8 device_release_driver+0x28/0x38 bus_remove_device+0xd4/0x158 device_del+0x160/0x3a0 unregister_dev_dax+0x30/0x68 devm_action_release+0x20/0x30 release_nodes+0x150/0x240 devres_release_all+0x6c/0x1d0 device_release_driver_internal+0x10c/0x1c8 driver_detach+0xac/0x170 bus_remove_driver+0x64/0x130 driver_unregister+0x34/0x60 dax_pmem_exit+0x14/0xffc4 [dax_pmem] __arm64_sys_delete_module+0x18c/0x2d0 el0_svc_common.constprop.2+0x78/0x168 do_el0_svc+0x34/0xa0 el0_sync_handler+0xe0/0x188 el0_sync+0x164/0x180 It is caused by the bogus nid (-1). Although the root cause is pmem dax translates from pxm to node_id incorrectly due to numa_off, it is worth hardening the codes in try_offline_node(), quiting if !pgdat. Signed-off-by: Jia He <justin.he@xxxxxxx> --- mm/memory_hotplug.c | 3 +++ 1 file changed, 3 insertions(+) diff --git a/mm/memory_hotplug.c b/mm/memory_hotplug.c index da374cd3d45b..e1e290577b45 100644 --- a/mm/memory_hotplug.c +++ b/mm/memory_hotplug.c @@ -1680,6 +1680,9 @@ void try_offline_node(int nid) pg_data_t *pgdat = NODE_DATA(nid); int rc; + if (WARN_ON(!pgdat)) + return; + /* * If the node still spans pages (especially ZONE_DEVICE), don't * offline it. A node spans memory after move_pfn_range_to_zone(), -- 2.17.1
