From 2f303b74a62fb74983c0a66e2df353be963c527c Mon Sep 17 00:00:00 2001 From: Paolo Bonzini Date: Wed, 25 Sep 2013 13:53:07 +0200 Subject: [PATCH] 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:[] mmu_shrink+0x5c/0x1b0 [kvm] Pid: 55, comm: kswapd0 Not tainted 3.4.34_preempt-rt Call Trace: [] __might_sleep+0xfd/0x160 [] rt_spin_lock+0x24/0x50 [] mmu_shrink+0xec/0x1b0 [kvm] [] shrink_slab+0x17d/0x3a0 [] ? mem_cgroup_iter+0x130/0x260 [] balance_pgdat+0x54a/0x730 [] ? set_pgdat_percpu_threshold+0xa7/0xd0 [] kswapd+0x18f/0x490 [] ? get_parent_ip+0x11/0x50 [] ? __init_waitqueue_head+0x50/0x50 [] ? balance_pgdat+0x730/0x730 [] kthread+0xdb/0xe0 [] ? finish_task_switch+0x52/0x100 [] kernel_thread_helper+0x4/0x10 [] ? __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 Cc: kvm@vger.kernel.org Cc: gleb@redhat.com Cc: jan.kiszka@siemens.com Reviewed-by: Gleb Natapov Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/locking.txt | 2 +- arch/x86/kvm/mmu.c | 5 ++--- arch/x86/kvm/x86.c | 8 ++++---- include/linux/kvm_host.h | 2 +- virt/kvm/kvm_main.c | 18 +++++++++--------- 5 files changed, 17 insertions(+), 18 deletions(-) diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt index ba9e1c2150c2..f8869410d40c 100644 --- 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 dce0df8150df..cf95cfe050a6 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4428,7 +4428,7 @@ mmu_shrink_scan(struct shrinker *shrink, struct shrink_control *sc) int nr_to_scan = sc->nr_to_scan; unsigned long freed = 0; - raw_spin_lock(&kvm_lock); + spin_lock(&kvm_lock); list_for_each_entry(kvm, &vm_list, vm_list) { int idx; @@ -4478,9 +4478,8 @@ unlock: break; } - raw_spin_unlock(&kvm_lock); + spin_unlock(&kvm_lock); return freed; - } static unsigned long diff --git a/arch/x86/kvm/x86.c b/arch/x86/kvm/x86.c index e5ca72a5cdb6..187f824b1454 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5263,7 +5263,7 @@ 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) @@ -5273,7 +5273,7 @@ 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) { /* @@ -5426,12 +5426,12 @@ 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 749bdb12cd15..7c961e1e9270 100644 --- a/include/linux/kvm_host.h +++ b/include/linux/kvm_host.h @@ -142,7 +142,7 @@ 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 eb94343c2ed2..d469114aff09 100644 --- 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]); @@ -3054,10 +3054,10 @@ 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; } @@ -3071,12 +3071,12 @@ 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; } -- 2.34.1