xen/smp: Fix bringup bug in AP code.
The CPU hotplug code has now a callback to help bring up the CPU.
Without the call we end up getting:
BUG: soft lockup - CPU#0 stuck for 29s! [migration/0:6]
Modules linked in:
CPU ] Pid: 6, comm: migration/0 Not tainted 3.3.0upstream-01180-ged378a5 #1 Dell Inc. PowerEdge T105 /0RR825
RIP: e030:[<ffffffff810d3b8b>] [<ffffffff810d3b8b>] stop_machine_cpu_stop+0x7b/0xf0
RSP: e02b:ffff8800ceaabdb0 EFLAGS: 00000293
.. snip..
Call Trace:
[<ffffffff810d3b10>] ? stop_one_cpu_nowait+0x50/0x50
[<ffffffff810d3841>] cpu_stopper_thread+0xf1/0x1c0
[<ffffffff815a9776>] ? __schedule+0x3c6/0x760
[<ffffffff815aa749>] ? _raw_spin_unlock_irqrestore+0x19/0x30
[<ffffffff810d3750>] ? res_counter_charge+0x150/0x150
[<ffffffff8108dc76>] kthread+0x96/0xa0
[<ffffffff815b27e4>] kernel_thread_helper+0x4/0x10
[<ffffffff815aacbc>] ? retint_restore_ar
Thix fixes it.
Acked-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Konrad Rzeszutek Wilk <konrad.wilk@oracle.com>
diff --git a/arch/x86/xen/smp.c b/arch/x86/xen/smp.c
index 449f868..240def4 100644
--- a/arch/x86/xen/smp.c
+++ b/arch/x86/xen/smp.c
@@ -75,8 +75,14 @@
xen_setup_cpu_clockevents();
+ notify_cpu_starting(cpu);
+
+ ipi_call_lock();
set_cpu_online(cpu, true);
+ ipi_call_unlock();
+
this_cpu_write(cpu_state, CPU_ONLINE);
+
wmb();
/* We can take interrupts now: we're officially "up". */