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
..
acpi	Additional ACPICA material for v4.2-rc1	2015-07-02 17:11:28 -07:00
asm-generic	- Support for HS38 cores based on ARCv2 ISA	2015-07-01 09:24:26 -07:00
clocksource
crypto	crypto: rng - Do not free default RNG when it becomes unused	2015-06-22 15:49:18 +08:00
drm	drm: use kvfree() in drm_free_large()	2015-06-30 19:44:59 -07:00
dt-bindings	The changes to the common clock framework for 4.2 are dominated by new	2015-07-01 19:22:00 -07:00
keys
kvm
linux	sched, preempt_notifier: separate notifier registration from static_key inc/dec	2015-07-03 18:55:00 +02:00
math-emu
media	Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/cooloney/linux-leds	2015-07-01 19:09:11 -07:00
memory
misc
net	net: Kill sock->sk_protinfo	2015-06-28 16:55:44 -07:00
pcmcia
ras	tracing: add trace event for memory-failure	2015-06-24 17:49:43 -07:00
rdma	IB/mad: Add final OPA MAD processing	2015-06-12 14:49:18 -04:00
rxrpc
scsi	SCSI misc on 20150622	2015-06-23 15:55:44 -07:00
soc	Merge branch 'for-linus' of git://ftp.arm.linux.org.uk/~rmk/linux-arm	2015-06-26 12:20:00 -07:00
sound	ASoC: Further updates for v4.2	2015-06-22 11:32:41 +02:00
target	SCSI misc on 20150622	2015-06-23 15:55:44 -07:00
trace	Merge branch 'for-linus-4.2' of git://git.kernel.org/pub/scm/linux/kernel/git/mason/linux-btrfs	2015-06-30 20:07:45 -07:00
uapi	Merge branch 'drm-next-4.2' of git://people.freedesktop.org/~agd5f/linux	2015-07-02 14:38:15 -07:00
video	Merge branch 'drm-next' of git://people.freedesktop.org/~airlied/linux	2015-06-26 13:18:51 -07:00
xen
Kbuild