4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> commit 98b8e4e5c17bf87c1b18ed929472051dab39878c upstream. Calling acpi_wmi_init() at the subsys_initcall() level causes ordering issues to appear on some systems and they are difficult to reproduce, because there is no guaranteed ordering between subsys_initcall() calls, so they may occur in different orders on different systems. In particular, commit 86d9f48534e8 (mm/slab: fix kmemcg cache creation delayed issue) exposed one of these issues where genl_init() and acpi_wmi_init() are both called at the same initcall level, but the former must run before the latter so as to avoid a NULL pointer dereference. For this reason, move the acpi_wmi_init() invocation to the initcall_sync level which should still be early enough for things to work correctly in the WMI land. Link: https://marc.info/?t=151274596700002&r=1&w=2 Reported-by: Jonathan McDowell <noodles@xxxxxxxx> Reported-by: Joonsoo Kim <iamjoonsoo.kim@xxxxxxx> Tested-by: Jonathan McDowell <noodles@xxxxxxxx> Signed-off-by: Rafael J. Wysocki <rafael.j.wysocki@xxxxxxxxx> Signed-off-by: Darren Hart (VMware) <dvhart@xxxxxxxxxxxxx> Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> --- drivers/platform/x86/wmi.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- a/drivers/platform/x86/wmi.c +++ b/drivers/platform/x86/wmi.c @@ -848,5 +848,5 @@ static void __exit acpi_wmi_exit(void) pr_info("Mapper unloaded\n"); } -subsys_initcall(acpi_wmi_init); +subsys_initcall_sync(acpi_wmi_init); module_exit(acpi_wmi_exit);