KVM: Convert kvm_lock back to non-raw spinlock

In commit e935b8372cf8 ("KVM: Convert kvm_lock to raw_spinlock"),
the kvm_lock was made a raw lock.  However, the kvm mmu_shrink()
function tries to grab the (non-raw) mmu_lock within the scope of
the raw locked kvm_lock being held.  This leads to the following:

BUG: sleeping function called from invalid context at kernel/rtmutex.c:659
in_atomic(): 1, irqs_disabled(): 0, pid: 55, name: kswapd0
Preemption disabled at:[<ffffffffa0376eac>] mmu_shrink+0x5c/0x1b0 [kvm]

Pid: 55, comm: kswapd0 Not tainted 3.4.34_preempt-rt
Call Trace:
 [<ffffffff8106f2ad>] __might_sleep+0xfd/0x160
 [<ffffffff817d8d64>] rt_spin_lock+0x24/0x50
 [<ffffffffa0376f3c>] mmu_shrink+0xec/0x1b0 [kvm]
 [<ffffffff8111455d>] shrink_slab+0x17d/0x3a0
 [<ffffffff81151f00>] ? mem_cgroup_iter+0x130/0x260
 [<ffffffff8111824a>] balance_pgdat+0x54a/0x730
 [<ffffffff8111fe47>] ? set_pgdat_percpu_threshold+0xa7/0xd0
 [<ffffffff811185bf>] kswapd+0x18f/0x490
 [<ffffffff81070961>] ? get_parent_ip+0x11/0x50
 [<ffffffff81061970>] ? __init_waitqueue_head+0x50/0x50
 [<ffffffff81118430>] ? balance_pgdat+0x730/0x730
 [<ffffffff81060d2b>] kthread+0xdb/0xe0
 [<ffffffff8106e122>] ? finish_task_switch+0x52/0x100
 [<ffffffff817e1e94>] kernel_thread_helper+0x4/0x10
 [<ffffffff81060c50>] ? __init_kthread_worker+0x

After the previous patch, kvm_lock need not be a raw spinlock anymore,
so change it back.

Reported-by: Paul Gortmaker <paul.gortmaker@windriver.com>
Cc: kvm@vger.kernel.org
Cc: gleb@redhat.com
Cc: jan.kiszka@siemens.com
Reviewed-by: Gleb Natapov <gleb@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
(cherry picked from commit 2f303b74a62fb74983c0a66e2df353be963c527c)
Signed-off-by: Christoffer Dall <christoffer.dall@linaro.org>

diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt
index b1f5de22d090619527f80c9017197553bcc9d1e5..ba035c33d01c0d323c156868b3b8d8432a9485c3 100644 (file)
--- a/Documentation/virtual/kvm/locking.txt
+++ b/Documentation/virtual/kvm/locking.txt
@@ -132,7 +132,7 @@ See the comments in spte_has_volatile_bits() and mmu_spte_update().
 ------------
 
 Name:          kvm_lock
-Type:          raw_spinlock
+Type:          spinlock_t
 Arch:          any
 Protects:      - vm_list
 

diff --git a/arch/x86/kvm/mmu.c b/arch/x86/kvm/mmu.c
index 004cc87b781c2694a0f6428ef8b6614ff60711b7..3c1877bbfe6a1481d02a65096fb17bceb50a5c12 100644 (file)
--- a/arch/x86/kvm/mmu.c
+++ b/arch/x86/kvm/mmu.c
@@ -4220,7 +4220,7 @@ static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
        if (nr_to_scan == 0)
                goto out;
 
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
 
        list_for_each_entry(kvm, &vm_list, vm_list) {
                int idx;
@@ -4256,7 +4256,7 @@ static int mmu_shrink(struct shrinker *shrink, struct shrink_control *sc)
                break;
        }
 
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
 
 out:
        return percpu_counter_read_positive(&kvm_total_used_mmu_pages);

diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c
index 894003d79d2216ba4cfd431f506d24d798ad970b..96765c116c26739e781590efaef99a62aa17a8e1 100644 (file)
--- a/arch/x86/kvm/x86.c
+++ b/arch/x86/kvm/x86.c
@@ -5104,7 +5104,7 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
 
        smp_call_function_single(freq->cpu, tsc_khz_changed, freq, 1);
 
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list) {
                kvm_for_each_vcpu(i, vcpu, kvm) {
                        if (vcpu->cpu != freq->cpu)
@@ -5114,7 +5114,7 @@ static int kvmclock_cpufreq_notifier(struct notifier_block *nb, unsigned long va
                                send_ipi = 1;
                }
        }
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
 
        if (freq->old < freq->new && send_ipi) {
                /*
@@ -5261,12 +5261,12 @@ static void pvclock_gtod_update_fn(struct work_struct *work)
        struct kvm_vcpu *vcpu;
        int i;
 
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                kvm_for_each_vcpu(i, vcpu, kvm)
                        set_bit(KVM_REQ_MASTERCLOCK_UPDATE, &vcpu->requests);
        atomic_set(&kvm_guest_has_master_clock, 0);
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
 }
 
 static DECLARE_WORK(pvclock_gtod_work, pvclock_gtod_update_fn);

diff --git a/include/linux/kvm_host.h b/include/linux/kvm_host.h
index dbbd782152048d5c4f199d486dbc24da51756cae..97e39fc020204aa7a28291ac0ef0c045c7e228f2 100644 (file)
--- a/include/linux/kvm_host.h
+++ b/include/linux/kvm_host.h
@@ -133,7 +133,7 @@ struct kvm;
 struct kvm_vcpu;
 extern struct kmem_cache *kvm_vcpu_cache;
 
-extern raw_spinlock_t kvm_lock;
+extern spinlock_t kvm_lock;
 extern struct list_head vm_list;
 
 struct kvm_io_range {

diff --git a/virt/kvm/kvm_main.c b/virt/kvm/kvm_main.c
index 6bc0481bf8e51ad7fb3fc13a903d027849ef1ada..8b47fd241a613858fbdbf7845af8c0cba5788d15 100644 (file)
--- a/virt/kvm/kvm_main.c
+++ b/virt/kvm/kvm_main.c
@@ -70,7 +70,7 @@ MODULE_LICENSE("GPL");
  *             kvm->lock --> kvm->slots_lock --> kvm->irq_lock
  */
 
-DEFINE_RAW_SPINLOCK(kvm_lock);
+DEFINE_SPINLOCK(kvm_lock);
 static DEFINE_RAW_SPINLOCK(kvm_count_lock);
 LIST_HEAD(vm_list);
 
@@ -491,9 +491,9 @@ static struct kvm *kvm_create_vm(unsigned long type)
        if (r)
                goto out_err;
 
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_add(&kvm->vm_list, &vm_list);
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
 
        return kvm;
 
@@ -582,9 +582,9 @@ static void kvm_destroy_vm(struct kvm *kvm)
        struct mm_struct *mm = kvm->mm;
 
        kvm_arch_sync_events(kvm);
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_del(&kvm->vm_list);
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
        kvm_free_irq_routing(kvm);
        for (i = 0; i < KVM_NR_BUSES; i++)
                kvm_io_bus_destroy(kvm->buses[i]);
@@ -2974,10 +2974,10 @@ static int vm_stat_get(void *_offset, u64 *val)
        struct kvm *kvm;
 
        *val = 0;
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                *val += *(u32 *)((void *)kvm + offset);
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
        return 0;
 }
 
@@ -2991,12 +2991,12 @@ static int vcpu_stat_get(void *_offset, u64 *val)
        int i;
 
        *val = 0;
-       raw_spin_lock(&kvm_lock);
+       spin_lock(&kvm_lock);
        list_for_each_entry(kvm, &vm_list, vm_list)
                kvm_for_each_vcpu(i, vcpu, kvm)
                        *val += *(u32 *)((void *)vcpu + offset);
 
-       raw_spin_unlock(&kvm_lock);
+       spin_unlock(&kvm_lock);
        return 0;
 }