From: Thomas Gleixner tglx@linutronix.de
commit 8645e56a4ad6dcbf504872db7f14a2f67db88ef2 upstream.
xen_maybe_preempt_hcall() is called from the exception entry point xen_do_hypervisor_callback with interrupts disabled.
_cond_resched() evades the might_sleep() check in cond_resched() which would have caught that and schedule_debug() unfortunately lacks a check for irqs_disabled().
Enable interrupts around the call and use cond_resched() to catch future issues.
Fixes: fdfd811ddde3 ("x86/xen: allow privcmd hypercalls to be preempted") Signed-off-by: Thomas Gleixner tglx@linutronix.de Link: https://lore.kernel.org/r/878skypjrh.fsf@nanos.tec.linutronix.de Reviewed-by: Juergen Gross jgross@suse.com Signed-off-by: Boris Ostrovsky boris.ostrovsky@oracle.com Signed-off-by: Greg Kroah-Hartman gregkh@linuxfoundation.org
--- drivers/xen/preempt.c | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-)
--- a/drivers/xen/preempt.c +++ b/drivers/xen/preempt.c @@ -37,7 +37,9 @@ asmlinkage __visible void xen_maybe_pree * cpu. */ __this_cpu_write(xen_in_preemptible_hcall, false); - _cond_resched(); + local_irq_enable(); + cond_resched(); + local_irq_disable(); __this_cpu_write(xen_in_preemptible_hcall, true); } }