Peter Zijlstra 2ecd9d29ab sched, preempt_notifier: separate notifier registration from static_key inc/dec ... Commit 1cde2930e1 ("sched/preempt: Add static_key() to preempt_notifiers") had two problems. First, the preempt-notifier API needs to sleep with the addition of the static_key, we do however need to hold off preemption while modifying the preempt notifier list, otherwise a preemption could observe an inconsistent list state. KVM correctly registers and unregisters preempt notifiers with preemption disabled, so the sleep caused dmesg splats. Second, KVM registers and unregisters preemption notifiers very often (in vcpu_load/vcpu_put). With a single uniprocessor guest the static key would move between 0 and 1 continuously, hitting the slow path on every userspace exit. To fix this, wrap the static_key inc/dec in a new API, and call it from KVM. Fixes: 1cde2930e1 ("sched/preempt: Add static_key() to preempt_notifiers") Reported-by: Pontus Fuchs <pontus.fuchs@gmail.com> Reported-by: Takashi Iwai <tiwai@suse.de> Tested-by: Takashi Iwai <tiwai@suse.de> Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org> Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>		2015-07-03 18:55:00 +02:00
..
arm	arm64 updates for 4.2, mostly refactoring/clean-up:	2015-06-24 10:02:15 -07:00
Kconfig	KVM: Disable compat ioctl for s390	2015-02-09 12:44:14 +01:00
async_pf.c	mm: gup: kvm use get_user_pages_unlocked	2015-02-11 17:06:05 -08:00
async_pf.h	KVM: fix checkpatch.pl errors in kvm/async_pf.h	2015-06-19 17:16:25 +02:00
coalesced_mmio.c	KVM: move iodev.h from virt/kvm/ to include/kvm	2015-03-26 21:43:12 +00:00
coalesced_mmio.h	KVM: fix checkpatch.pl errors in kvm/coalesced_mmio.h	2015-06-19 17:16:26 +02:00
eventfd.c	KVM: move iodev.h from virt/kvm/ to include/kvm	2015-03-26 21:43:12 +00:00
irqchip.c	kvm: irqchip: Break up high order allocations of kvm_irq_routing_table	2015-06-19 17:16:25 +02:00
kvm_main.c	sched, preempt_notifier: separate notifier registration from static_key inc/dec	2015-07-03 18:55:00 +02:00
vfio.c	kvm: vfio: fix unregister kvm_device_ops of vfio	2014-10-24 13:30:47 +02:00
vfio.h	kvm: vfio: fix unregister kvm_device_ops of vfio	2014-10-24 13:30:47 +02:00