Commit c185ddec authored Jul 05, 2017 by Juergen Gross

xen/x86: fix cpu hotplug



Commit dc6416f1 ("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().

Cc: <stable@vger.kernel.org> # 4.12
Signed-off-by: Juergen Gross <jgross@suse.com>
Reviewed-by: Boris Ostrovsky <boris.ostrovsky@oracle.com>
Signed-off-by: Juergen Gross <jgross@suse.com>

parent 29d11cfd

arch/x86/xen/smp_pv.c

+2 −1

Original line number	Diff line number	Diff line
		@@ -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>
		@@ -413,7 +414,7 @@ static void xen_pv_play_dead(void) /* used only with HOTPLUG_CPU */
		*/
		tick_nohz_idle_enter();

		cpu_startup_entry(CPUHP_AP_ONLINE_IDLE);
		cpuhp_online_idle(CPUHP_AP_ONLINE_IDLE);
		}

		#else /* !CONFIG_HOTPLUG_CPU */

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