4.12-stable review patch. If anyone has any objections, please let me know.
------------------
From: Juergen Gross <jgross@xxxxxxxx>
commit c185ddec54657c145a0c2055e4b87918da24974f upstream.
Commit dc6416f1d711eb4c1726e845d653235dcaae12e1 ("xen/x86: Call
cpu_startup_entry(CPUHP_AP_ONLINE_IDLE) from xen_play_dead()")
introduced an error leading to a stack overflow of the idle task when
a cpu was brought offline/online many times: by calling
cpu_startup_entry() instead of returning at the end of xen_play_dead()
do_idle() would be entered again and again.
Don't use cpu_startup_entry(), but cpuhp_online_idle() instead allowing
to return from xen_play_dead().
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@xxxxxxxxxx>
Signed-off-by: Juergen Gross <jgross@xxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/x86/xen/smp_pv.c | 3 ++-
1 file changed, 2 insertions(+), 1 deletion(-)
--- a/arch/x86/xen/smp_pv.c
+++ b/arch/x86/xen/smp_pv.c
@@ -19,6 +19,7 @@
#include <linux/irq_work.h>
#include <linux/tick.h>
#include <linux/nmi.h>
+#include <linux/cpuhotplug.h>
#include <asm/paravirt.h>
#include <asm/desc.h>
@@ -417,7 +418,7 @@ static void xen_pv_play_dead(void) /* us
*/
tick_nohz_idle_enter();
- cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
+ cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
}
#else /* !CONFIG_HOTPLUG_CPU */