4.12-stable review patch. If anyone has any objections, please let me know.
------------------ From: Juergen Gross <[email protected]> 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 <[email protected]> Reviewed-by: Boris Ostrovsky <[email protected]> Signed-off-by: Juergen Gross <[email protected]> Signed-off-by: Greg Kroah-Hartman <[email protected]> --- 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 */
