* [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait
[not found] <20200424054837.5138-1-dave@stgolabs.net>
@ 2020-04-24 5:48 ` Davidlohr Bueso
2020-04-25 10:24 ` Paolo Bonzini
2020-05-18 8:51 ` Wanpeng Li
0 siblings, 2 replies; 4+ messages in thread
From: Davidlohr Bueso @ 2020-04-24 5:48 UTC (permalink / raw)
To: tglx, pbonzini
Cc: dave, kvm, will, Davidlohr Bueso, peterz, maz, bigeasy,
linux-kernel, rostedt, linux-mips, Paul Mackerras, joel,
torvalds, kvmarm
The use of any sort of waitqueue (simple or regular) for
wait/waking vcpus has always been an overkill and semantically
wrong. Because this is per-vcpu (which is blocked) there is
only ever a single waiting vcpu, thus no need for any sort of
queue.
As such, make use of the rcuwait primitive, with the following
considerations:
- rcuwait already provides the proper barriers that serialize
concurrent waiter and waker.
- Task wakeup is done in rcu read critical region, with a
stable task pointer.
- Because there is no concurrency among waiters, we need
not worry about rcuwait_wait_event() calls corrupting
the wait->task. As a consequence, this saves the locking
done in swait when modifying the queue. This also applies
to per-vcore wait for powerpc kvm-hv.
The x86 tscdeadline_latency test mentioned in 8577370fb0cb
("KVM: Use simple waitqueue for vcpu->wq") shows that, on avg,
latency is reduced by around 15-20% with this change.
Cc: Paul Mackerras <paulus@ozlabs.org>
Cc: kvmarm@lists.cs.columbia.edu
Cc: linux-mips@vger.kernel.org
Reviewed-by: Marc Zyngier <maz@kernel.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
arch/mips/kvm/mips.c | 6 ++----
arch/powerpc/include/asm/kvm_book3s.h | 2 +-
arch/powerpc/include/asm/kvm_host.h | 2 +-
arch/powerpc/kvm/book3s_hv.c | 22 ++++++++--------------
arch/powerpc/kvm/powerpc.c | 2 +-
arch/x86/kvm/lapic.c | 2 +-
include/linux/kvm_host.h | 10 +++++-----
virt/kvm/arm/arch_timer.c | 3 ++-
virt/kvm/arm/arm.c | 9 +++++----
virt/kvm/async_pf.c | 3 +--
virt/kvm/kvm_main.c | 19 +++++++++----------
11 files changed, 36 insertions(+), 44 deletions(-)
diff --git a/arch/mips/kvm/mips.c b/arch/mips/kvm/mips.c
index 8f05dd0a0f4e..fad6acce46e4 100644
--- a/arch/mips/kvm/mips.c
+++ b/arch/mips/kvm/mips.c
@@ -284,8 +284,7 @@ static enum hrtimer_restart kvm_mips_comparecount_wakeup(struct hrtimer *timer)
kvm_mips_callbacks->queue_timer_int(vcpu);
vcpu->arch.wait = 0;
- if (swq_has_sleeper(&vcpu->wq))
- swake_up_one(&vcpu->wq);
+ rcuwait_wake_up(&vcpu->wait);
return kvm_mips_count_timeout(vcpu);
}
@@ -511,8 +510,7 @@ int kvm_vcpu_ioctl_interrupt(struct kvm_vcpu *vcpu,
dvcpu->arch.wait = 0;
- if (swq_has_sleeper(&dvcpu->wq))
- swake_up_one(&dvcpu->wq);
+ rcuwait_wake_up(&dvcpu->wait);
return 0;
}
diff --git a/arch/powerpc/include/asm/kvm_book3s.h b/arch/powerpc/include/asm/kvm_book3s.h
index 506e4df2d730..6e5d85ba588d 100644
--- a/arch/powerpc/include/asm/kvm_book3s.h
+++ b/arch/powerpc/include/asm/kvm_book3s.h
@@ -78,7 +78,7 @@ struct kvmppc_vcore {
struct kvm_vcpu *runnable_threads[MAX_SMT_THREADS];
struct list_head preempt_list;
spinlock_t lock;
- struct swait_queue_head wq;
+ struct rcuwait wait;
spinlock_t stoltb_lock; /* protects stolen_tb and preempt_tb */
u64 stolen_tb;
u64 preempt_tb;
diff --git a/arch/powerpc/include/asm/kvm_host.h b/arch/powerpc/include/asm/kvm_host.h
index 1dc63101ffe1..337047ba4a56 100644
--- a/arch/powerpc/include/asm/kvm_host.h
+++ b/arch/powerpc/include/asm/kvm_host.h
@@ -751,7 +751,7 @@ struct kvm_vcpu_arch {
u8 irq_pending; /* Used by XIVE to signal pending guest irqs */
u32 last_inst;
- struct swait_queue_head *wqp;
+ struct rcuwait *waitp;
struct kvmppc_vcore *vcore;
int ret;
int trap;
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index 93493f0cbfe8..b8d42f523ca7 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -230,13 +230,11 @@ static bool kvmppc_ipi_thread(int cpu)
static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
{
int cpu;
- struct swait_queue_head *wqp;
+ struct rcuwait *wait;
- wqp = kvm_arch_vcpu_wq(vcpu);
- if (swq_has_sleeper(wqp)) {
- swake_up_one(wqp);
+ wait = kvm_arch_vcpu_get_wait(vcpu);
+ if (rcuwait_wake_up(wait))
++vcpu->stat.halt_wakeup;
- }
cpu = READ_ONCE(vcpu->arch.thread_cpu);
if (cpu >= 0 && kvmppc_ipi_thread(cpu))
@@ -2125,7 +2123,7 @@ static struct kvmppc_vcore *kvmppc_vcore_create(struct kvm *kvm, int id)
spin_lock_init(&vcore->lock);
spin_lock_init(&vcore->stoltb_lock);
- init_swait_queue_head(&vcore->wq);
+ rcuwait_init(&vcore->wait);
vcore->preempt_tb = TB_NIL;
vcore->lpcr = kvm->arch.lpcr;
vcore->first_vcpuid = id;
@@ -3784,7 +3782,6 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
ktime_t cur, start_poll, start_wait;
int do_sleep = 1;
u64 block_ns;
- DECLARE_SWAITQUEUE(wait);
/* Poll for pending exceptions and ceded state */
cur = start_poll = ktime_get();
@@ -3812,10 +3809,7 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
}
}
- prepare_to_swait_exclusive(&vc->wq, &wait, TASK_INTERRUPTIBLE);
-
if (kvmppc_vcore_check_block(vc)) {
- finish_swait(&vc->wq, &wait);
do_sleep = 0;
/* If we polled, count this as a successful poll */
if (vc->halt_poll_ns)
@@ -3828,8 +3822,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
vc->vcore_state = VCORE_SLEEPING;
trace_kvmppc_vcore_blocked(vc, 0);
spin_unlock(&vc->lock);
- schedule();
- finish_swait(&vc->wq, &wait);
+ rcuwait_wait_event(&vc->wait,
+ kvmppc_vcore_check_block(vc), TASK_INTERRUPTIBLE);
spin_lock(&vc->lock);
vc->vcore_state = VCORE_INACTIVE;
trace_kvmppc_vcore_blocked(vc, 1);
@@ -3940,7 +3934,7 @@ static int kvmppc_run_vcpu(struct kvm_run *kvm_run, struct kvm_vcpu *vcpu)
kvmppc_start_thread(vcpu, vc);
trace_kvm_guest_enter(vcpu);
} else if (vc->vcore_state == VCORE_SLEEPING) {
- swake_up_one(&vc->wq);
+ rcuwait_wake_up(&vc->wait);
}
}
@@ -4279,7 +4273,7 @@ static int kvmppc_vcpu_run_hv(struct kvm_run *run, struct kvm_vcpu *vcpu)
}
user_vrsave = mfspr(SPRN_VRSAVE);
- vcpu->arch.wqp = &vcpu->arch.vcore->wq;
+ vcpu->arch.waitp = &vcpu->arch.vcore->wait;
vcpu->arch.pgdir = kvm->mm->pgd;
vcpu->arch.state = KVMPPC_VCPU_BUSY_IN_HOST;
diff --git a/arch/powerpc/kvm/powerpc.c b/arch/powerpc/kvm/powerpc.c
index e15166b0a16d..4a074b587520 100644
--- a/arch/powerpc/kvm/powerpc.c
+++ b/arch/powerpc/kvm/powerpc.c
@@ -751,7 +751,7 @@ int kvm_arch_vcpu_create(struct kvm_vcpu *vcpu)
if (err)
goto out_vcpu_uninit;
- vcpu->arch.wqp = &vcpu->wq;
+ vcpu->arch.waitp = &vcpu->wait;
kvmppc_create_vcpu_debugfs(vcpu, vcpu->vcpu_id);
return 0;
diff --git a/arch/x86/kvm/lapic.c b/arch/x86/kvm/lapic.c
index 9af25c97612a..54345dc645ba 100644
--- a/arch/x86/kvm/lapic.c
+++ b/arch/x86/kvm/lapic.c
@@ -1833,7 +1833,7 @@ void kvm_lapic_expired_hv_timer(struct kvm_vcpu *vcpu)
/* If the preempt notifier has already run, it also called apic_timer_expired */
if (!apic->lapic_timer.hv_timer_in_use)
goto out;
- WARN_ON(swait_active(&vcpu->wq));
+ WARN_ON(rcuwait_active(&vcpu->wait));
cancel_hv_timer(apic);
apic_timer_expired(apic);
diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index 6d58beb65454..fc34021546bd 100644
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -23,7 +23,7 @@
#include <linux/irqflags.h>
#include <linux/context_tracking.h>
#include <linux/irqbypass.h>
-#include <linux/swait.h>
+#include <linux/rcuwait.h>
#include <linux/refcount.h>
#include <linux/nospec.h>
#include <asm/signal.h>
@@ -277,7 +277,7 @@ struct kvm_vcpu {
struct mutex mutex;
struct kvm_run *run;
- struct swait_queue_head wq;
+ struct rcuwait wait;
struct pid __rcu *pid;
int sigset_active;
sigset_t sigset;
@@ -956,12 +956,12 @@ static inline bool kvm_arch_has_assigned_device(struct kvm *kvm)
}
#endif
-static inline struct swait_queue_head *kvm_arch_vcpu_wq(struct kvm_vcpu *vcpu)
+static inline struct rcuwait *kvm_arch_vcpu_get_wait(struct kvm_vcpu *vcpu)
{
#ifdef __KVM_HAVE_ARCH_WQP
- return vcpu->arch.wqp;
+ return vcpu->arch.waitp;
#else
- return &vcpu->wq;
+ return &vcpu->wait;
#endif
}
diff --git a/virt/kvm/arm/arch_timer.c b/virt/kvm/arm/arch_timer.c
index 93bd59b46848..d5024416e722 100644
--- a/virt/kvm/arm/arch_timer.c
+++ b/virt/kvm/arm/arch_timer.c
@@ -571,6 +571,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
{
struct arch_timer_cpu *timer = vcpu_timer(vcpu);
struct timer_map map;
+ struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
if (unlikely(!timer->enabled))
return;
@@ -593,7 +594,7 @@ void kvm_timer_vcpu_put(struct kvm_vcpu *vcpu)
if (map.emul_ptimer)
soft_timer_cancel(&map.emul_ptimer->hrtimer);
- if (swait_active(kvm_arch_vcpu_wq(vcpu)))
+ if (rcuwait_active(wait))
kvm_timer_blocking(vcpu);
/*
diff --git a/virt/kvm/arm/arm.c b/virt/kvm/arm/arm.c
index 48d0ec44ad77..479f36d02418 100644
--- a/virt/kvm/arm/arm.c
+++ b/virt/kvm/arm/arm.c
@@ -579,16 +579,17 @@ void kvm_arm_resume_guest(struct kvm *kvm)
kvm_for_each_vcpu(i, vcpu, kvm) {
vcpu->arch.pause = false;
- swake_up_one(kvm_arch_vcpu_wq(vcpu));
+ rcuwait_wake_up(kvm_arch_vcpu_get_wait(vcpu));
}
}
static void vcpu_req_sleep(struct kvm_vcpu *vcpu)
{
- struct swait_queue_head *wq = kvm_arch_vcpu_wq(vcpu);
+ struct rcuwait *wait = kvm_arch_vcpu_get_wait(vcpu);
- swait_event_interruptible_exclusive(*wq, ((!vcpu->arch.power_off) &&
- (!vcpu->arch.pause)));
+ rcuwait_wait_event(wait,
+ (!vcpu->arch.power_off) &&(!vcpu->arch.pause),
+ TASK_INTERRUPTIBLE);
if (vcpu->arch.power_off || vcpu->arch.pause) {
/* Awaken to handle a signal, request we sleep again later. */
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c
index 15e5b037f92d..10b533f641a6 100644
--- a/virt/kvm/async_pf.c
+++ b/virt/kvm/async_pf.c
@@ -80,8 +80,7 @@ static void async_pf_execute(struct work_struct *work)
trace_kvm_async_pf_completed(addr, cr2_or_gpa);
- if (swq_has_sleeper(&vcpu->wq))
- swake_up_one(&vcpu->wq);
+ rcuwait_wake_up(&vcpu->wait);
mmput(mm);
kvm_put_kvm(vcpu->kvm);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 74bdb7bf3295..f027ae3598e8 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -341,7 +341,7 @@ static void kvm_vcpu_init(struct kvm_vcpu *vcpu, struct kvm *kvm, unsigned id)
vcpu->kvm = kvm;
vcpu->vcpu_id = id;
vcpu->pid = NULL;
- init_swait_queue_head(&vcpu->wq);
+ rcuwait_init(&vcpu->wait);
kvm_async_pf_vcpu_init(vcpu);
vcpu->pre_pcpu = -1;
@@ -2671,7 +2671,6 @@ static int kvm_vcpu_check_block(struct kvm_vcpu *vcpu)
void kvm_vcpu_block(struct kvm_vcpu *vcpu)
{
ktime_t start, cur;
- DECLARE_SWAITQUEUE(wait);
bool waited = false;
u64 block_ns;
@@ -2697,8 +2696,9 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
} while (single_task_running() && ktime_before(cur, stop));
}
+ prepare_to_rcuwait(&vcpu->wait);
for (;;) {
- prepare_to_swait_exclusive(&vcpu->wq, &wait, TASK_INTERRUPTIBLE);
+ set_current_state(TASK_INTERRUPTIBLE);
if (kvm_vcpu_check_block(vcpu) < 0)
break;
@@ -2706,8 +2706,7 @@ void kvm_vcpu_block(struct kvm_vcpu *vcpu)
waited = true;
schedule();
}
-
- finish_swait(&vcpu->wq, &wait);
+ finish_rcuwait(&vcpu->wait);
cur = ktime_get();
out:
kvm_arch_vcpu_unblocking(vcpu);
@@ -2738,11 +2737,10 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_block);
bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
{
- struct swait_queue_head *wqp;
+ struct rcuwait *wait;
- wqp = kvm_arch_vcpu_wq(vcpu);
- if (swq_has_sleeper(wqp)) {
- swake_up_one(wqp);
+ wait = kvm_arch_vcpu_get_wait(vcpu);
+ if (rcuwait_wake_up(wait)) {
WRITE_ONCE(vcpu->ready, true);
++vcpu->stat.halt_wakeup;
return true;
@@ -2884,7 +2882,8 @@ void kvm_vcpu_on_spin(struct kvm_vcpu *me, bool yield_to_kernel_mode)
continue;
if (vcpu == me)
continue;
- if (swait_active(&vcpu->wq) && !vcpu_dy_runnable(vcpu))
+ if (rcuwait_active(&vcpu->wait) &&
+ !vcpu_dy_runnable(vcpu))
continue;
if (READ_ONCE(vcpu->preempted) && yield_to_kernel_mode &&
!kvm_arch_vcpu_in_kernel(vcpu))
--
2.16.4
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait
2020-04-24 5:48 ` [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait Davidlohr Bueso
@ 2020-04-25 10:24 ` Paolo Bonzini
2020-04-25 22:30 ` Davidlohr Bueso
2020-05-18 8:51 ` Wanpeng Li
1 sibling, 1 reply; 4+ messages in thread
From: Paolo Bonzini @ 2020-04-25 10:24 UTC (permalink / raw)
To: Davidlohr Bueso, tglx
Cc: kvm, will, Davidlohr Bueso, peterz, maz, bigeasy, linux-kernel,
rostedt, linux-mips, Paul Mackerras, joel, torvalds, kvmarm
I'm squashing this in to keep the changes compared to the current code minimal,
and queuing the series.
Thanks,
Paolo
diff --git a/arch/powerpc/kvm/book3s_hv.c b/arch/powerpc/kvm/book3s_hv.c
index bbefa2a7f950..feca3118b17f 100644
--- a/arch/powerpc/kvm/book3s_hv.c
+++ b/arch/powerpc/kvm/book3s_hv.c
@@ -230,10 +230,10 @@ static bool kvmppc_ipi_thread(int cpu)
static void kvmppc_fast_vcpu_kick_hv(struct kvm_vcpu *vcpu)
{
int cpu;
- struct rcuwait *wait;
+ struct rcuwait *waitp;
- wait = kvm_arch_vcpu_get_wait(vcpu);
- if (rcuwait_wake_up(wait))
+ waitp = kvm_arch_vcpu_get_wait(vcpu);
+ if (rcuwait_wake_up(waitp))
++vcpu->stat.halt_wakeup;
cpu = READ_ONCE(vcpu->arch.thread_cpu);
@@ -3814,7 +3814,10 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
}
}
+ prepare_to_rcuwait(&vc->wait);
+ set_current_state(TASK_INTERRUPTIBLE);
if (kvmppc_vcore_check_block(vc)) {
+ finish_rcuwait(&vc->wait);
do_sleep = 0;
/* If we polled, count this as a successful poll */
if (vc->halt_poll_ns)
@@ -3827,8 +3830,8 @@ static void kvmppc_vcore_blocked(struct kvmppc_vcore *vc)
vc->vcore_state = VCORE_SLEEPING;
trace_kvmppc_vcore_blocked(vc, 0);
spin_unlock(&vc->lock);
- rcuwait_wait_event(&vc->wait,
- kvmppc_vcore_check_block(vc), TASK_INTERRUPTIBLE);
+ schedule();
+ finish_rcuwait(&vc->wait);
spin_lock(&vc->lock);
vc->vcore_state = VCORE_INACTIVE;
trace_kvmppc_vcore_blocked(vc, 1);
diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 7c2d18c12d87..c671de51a753 100644
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -2737,10 +2737,10 @@ EXPORT_SYMBOL_GPL(kvm_vcpu_block);
bool kvm_vcpu_wake_up(struct kvm_vcpu *vcpu)
{
- struct rcuwait *wait;
+ struct rcuwait *waitp;
- wait = kvm_arch_vcpu_get_wait(vcpu);
- if (rcuwait_wake_up(wait)) {
+ waitp = kvm_arch_vcpu_get_wait(vcpu);
+ if (rcuwait_wake_up(waitp)) {
WRITE_ONCE(vcpu->ready, true);
++vcpu->stat.halt_wakeup;
return true;
_______________________________________________
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kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply related [flat|nested] 4+ messages in thread
* Re: [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait
2020-04-25 10:24 ` Paolo Bonzini
@ 2020-04-25 22:30 ` Davidlohr Bueso
0 siblings, 0 replies; 4+ messages in thread
From: Davidlohr Bueso @ 2020-04-25 22:30 UTC (permalink / raw)
To: Paolo Bonzini
Cc: kvm, will, Davidlohr Bueso, peterz, maz, bigeasy, linux-kernel,
rostedt, linux-mips, Paul Mackerras, joel, tglx, torvalds,
kvmarm
On Sat, 25 Apr 2020, Paolo Bonzini wrote:
>I'm squashing this in to keep the changes compared to the current code minimal,
>and queuing the series.
Thanks!
_______________________________________________
kvmarm mailing list
kvmarm@lists.cs.columbia.edu
https://lists.cs.columbia.edu/mailman/listinfo/kvmarm
^ permalink raw reply [flat|nested] 4+ messages in thread
* Re: [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait
2020-04-24 5:48 ` [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait Davidlohr Bueso
2020-04-25 10:24 ` Paolo Bonzini
@ 2020-05-18 8:51 ` Wanpeng Li
1 sibling, 0 replies; 4+ messages in thread
From: Wanpeng Li @ 2020-05-18 8:51 UTC (permalink / raw)
To: Davidlohr Bueso
Cc: kvm, will, Davidlohr Bueso, Peter Zijlstra, Marc Zyngier,
Sebastian Sewior, LKML, Steven Rostedt, linux-mips,
Paul Mackerras, joel, Paolo Bonzini, Thomas Gleixner,
Linus Torvalds, kvmarm
On Fri, 24 Apr 2020 at 13:53, Davidlohr Bueso <dave@stgolabs.net> wrote:
>
> The use of any sort of waitqueue (simple or regular) for
> wait/waking vcpus has always been an overkill and semantically
> wrong. Because this is per-vcpu (which is blocked) there is
> only ever a single waiting vcpu, thus no need for any sort of
> queue.
>
> As such, make use of the rcuwait primitive, with the following
> considerations:
>
> - rcuwait already provides the proper barriers that serialize
> concurrent waiter and waker.
>
> - Task wakeup is done in rcu read critical region, with a
> stable task pointer.
>
> - Because there is no concurrency among waiters, we need
> not worry about rcuwait_wait_event() calls corrupting
> the wait->task. As a consequence, this saves the locking
> done in swait when modifying the queue. This also applies
> to per-vcore wait for powerpc kvm-hv.
>
> The x86 tscdeadline_latency test mentioned in 8577370fb0cb
> ("KVM: Use simple waitqueue for vcpu->wq") shows that, on avg,
> latency is reduced by around 15-20% with this change.
>
This is splatting when I run linux guest on latest kvm/queue.
[24726.009187] =============================
[24726.009193] WARNING: suspicious RCU usage
[24726.009201] 5.7.0-rc2+ #3 Not tainted
[24726.009207] -----------------------------
[24726.009215] ./include/linux/rcuwait.h:34 suspicious
rcu_dereference_check() usage!
[24726.009222]
other info that might help us debug this:
[24726.009229]
rcu_scheduler_active = 2, debug_locks = 1
[24726.009237] 2 locks held by qemu-system-x86/6094:
[24726.009244] #0: ffff88837b6cb990 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x191/0xbb0 [kvm]
[24726.009347] #1: ffffc900036c2c68 (&kvm->srcu){....}-{0:0}, at:
kvm_arch_vcpu_ioctl_run+0x17f1/0x5680 [kvm]
[24726.009386]
stack backtrace:
[24726.009394] CPU: 5 PID: 6094 Comm: qemu-system-x86 Not tainted 5.7.0-rc2+ #3
[24726.009400] Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY,
BIOS FBKTC1AUS 02/16/2016
[24726.009405] Call Trace:
[24726.009418] dump_stack+0x98/0xd5
[24726.009432] lockdep_rcu_suspicious+0x123/0x170
[24726.009465] kvm_vcpu_on_spin+0x46f/0x5d0 [kvm]
[24726.009497] handle_pause+0x7e/0x3e0 [kvm_intel]
[24726.009517] vmx_handle_exit+0x1fe/0x1000 [kvm_intel]
[24726.009547] ? kvm_arch_vcpu_ioctl_run+0x17c5/0x5680 [kvm]
[24726.009586] kvm_arch_vcpu_ioctl_run+0x18f5/0x5680 [kvm]
[24726.009595] ? check_chain_key+0x26e/0x670
[24726.009651] ? kvm_arch_vcpu_runnable+0x540/0x540 [kvm]
[24726.009667] ? tomoyo_execute_permission+0x4b0/0x4b0
[24726.009677] ? sched_clock+0x31/0x40
[24726.009726] kvm_vcpu_ioctl+0x5d2/0xbb0 [kvm]
[24726.009754] ? kvm_vcpu_ioctl+0x5d2/0xbb0 [kvm]
[24726.009786] ? kvm_set_memory_region+0x90/0x90 [kvm]
[24726.009819] ? __fget_files+0x2d4/0x420
[24726.009837] ? do_dup2+0x660/0x660
[24726.009847] ? lock_acquire+0x1e5/0x660
[24726.009864] ? tomoyo_file_ioctl+0x19/0x20
[24726.009880] ksys_ioctl+0x3d2/0x1390
[24726.009900] ? generic_block_fiemap+0x70/0x70
[24726.009911] ? rcu_read_lock_sched_held+0xb4/0xe0
[24726.009920] ? rcu_read_lock_any_held.part.9+0x20/0x20
[24726.009935] ? __x64_sys_futex+0x1a1/0x400
[24726.009943] ? __kasan_check_write+0x14/0x20
[24726.009951] ? switch_fpu_return+0x181/0x3e0
[24726.009963] ? do_futex+0x14e0/0x14e0
[24726.009970] ? lockdep_hardirqs_off+0x1df/0x2d0
[24726.009977] ? syscall_return_slowpath+0x66/0x9d0
[24726.009987] ? do_syscall_64+0x8e/0xae0
[24726.009995] ? entry_SYSCALL_64_after_hwframe+0x49/0xb3
[24726.010012] __x64_sys_ioctl+0x73/0xb0
[24726.010023] do_syscall_64+0x108/0xae0
[24726.010032] ? trace_hardirqs_on_thunk+0x1a/0x1c
[24726.010042] ? syscall_return_slowpath+0x9d0/0x9d0
[24726.010048] ? trace_hardirqs_off_thunk+0x1a/0x1c
[24726.010059] ? trace_hardirqs_off_caller+0x28/0x1b0
[24726.010074] ? trace_hardirqs_off_thunk+0x1a/0x1c
[24726.010092] entry_SYSCALL_64_after_hwframe+0x49/0xb3
[25372.530417] =============================
[25372.530420] WARNING: suspicious RCU usage
[25372.530425] 5.7.0-rc2+ #3 Not tainted
[25372.530428] -----------------------------
[25372.530432] ./include/linux/rcuwait.h:34 suspicious
rcu_dereference_check() usage!
[25372.530436]
other info that might help us debug this:
[25372.530440]
rcu_scheduler_active = 2, debug_locks = 1
[25372.530443] 1 lock held by qemu-system-x86/6433:
[25372.530447] #0: ffff88837b6cb990 (&vcpu->mutex){+.+.}-{3:3}, at:
kvm_vcpu_ioctl+0x191/0xbb0 [kvm]
[25372.530483]
stack backtrace:
[25372.530487] CPU: 1 PID: 6433 Comm: qemu-system-x86 Not tainted 5.7.0-rc2+ #3
[25372.530491] Hardware name: LENOVO ThinkCentre M8500t-N000/SHARKBAY,
BIOS FBKTC1AUS 02/16/2016
[25372.530495] Call Trace:
[25372.530504] dump_stack+0x98/0xd5
[25372.530513] lockdep_rcu_suspicious+0x123/0x170
[25372.530547] kvm_lapic_expired_hv_timer+0x1ad/0x1f0 [kvm]
[25372.530559] vmx_vcpu_run+0x1892/0x2c60 [kvm_intel]
[25372.530568] ? rcu_preempt_deferred_qs_handler+0x20/0x40
[25372.530579] ? clear_atomic_switch_msr+0x970/0x970 [kvm_intel]
[25372.530586] ? rcu_read_lock_any_held.part.9+0x20/0x20
[25372.530613] kvm_arch_vcpu_ioctl_run+0x1579/0x5680 [kvm]
[25372.530619] ? check_chain_key+0x26e/0x670
[25372.530654] ? kvm_arch_vcpu_runnable+0x540/0x540 [kvm]
[25372.530665] ? tomoyo_execute_permission+0x4b0/0x4b0
[25372.530671] ? sched_clock+0x31/0x40
[25372.530678] ? sched_clock_cpu+0x1b/0x1b0
[25372.530706] kvm_vcpu_ioctl+0x5d2/0xbb0 [kvm]
[25372.530724] ? kvm_vcpu_ioctl+0x5d2/0xbb0 [kvm]
[25372.530744] ? kvm_set_memory_region+0x90/0x90 [kvm]
[25372.530764] ? __fget_files+0x2d4/0x420
[25372.530775] ? do_dup2+0x660/0x660
[25372.530779] ? vfs_iter_write+0xb0/0xb0
[25372.530785] ? rcu_read_lock_held+0xb4/0xc0
[25372.530795] ? tomoyo_file_ioctl+0x19/0x20
[25372.530806] ksys_ioctl+0x3d2/0x1390
[25372.530814] ? do_dup2+0x660/0x660
[25372.530821] ? generic_block_fiemap+0x70/0x70
[25372.530833] ? __kasan_check_write+0x14/0x20
[25372.530838] ? fput_many+0x20/0x140
[25372.530844] ? fput+0x13/0x20
[25372.530848] ? do_writev+0x175/0x320
[25372.530856] ? lockdep_hardirqs_off+0x1df/0x2d0
[25372.530861] ? syscall_return_slowpath+0x66/0x9d0
[25372.530867] ? do_syscall_64+0x8e/0xae0
[25372.530872] ? entry_SYSCALL_64_after_hwframe+0x49/0xb3
[25372.530883] __x64_sys_ioctl+0x73/0xb0
[25372.530890] do_syscall_64+0x108/0xae0
[25372.530894] ? switch_fpu_return+0x181/0x3e0
[25372.530899] ? trace_hardirqs_on_thunk+0x1a/0x1c
[25372.530905] ? syscall_return_slowpath+0x9d0/0x9d0
[25372.530908] ? trace_hardirqs_off_thunk+0x1a/0x1c
[25372.530917] ? trace_hardirqs_off_caller+0x28/0x1b0
[25372.530926] ? trace_hardirqs_off_thunk+0x1a/0x1c
[25372.530937] entry_SYSCALL_64_after_hwframe+0x49/0xb3
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2020-04-24 5:48 ` [PATCH 5/5] kvm: Replace vcpu->swait with rcuwait Davidlohr Bueso
2020-04-25 10:24 ` Paolo Bonzini
2020-04-25 22:30 ` Davidlohr Bueso
2020-05-18 8:51 ` Wanpeng Li
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