Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755450Ab3IPOGg (ORCPT ); Mon, 16 Sep 2013 10:06:36 -0400 Received: from mail-ee0-f54.google.com ([74.125.83.54]:59024 "EHLO mail-ee0-f54.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1754226Ab3IPOGa (ORCPT ); Mon, 16 Sep 2013 10:06:30 -0400 From: Paolo Bonzini To: linux-kernel@vger.kernel.org Cc: Paul Gortmaker , stable@vger.kernel.org, kvm@vger.kernel.org, gleb@redhat.com, jan.kiszka@siemens.com Subject: [PATCH 3/3] KVM: Convert kvm_lock back to non-raw spinlock Date: Mon, 16 Sep 2013 16:06:13 +0200 Message-Id: <1379340373-5135-4-git-send-email-pbonzini@redhat.com> X-Mailer: git-send-email 1.8.3.1 In-Reply-To: <1379340373-5135-1-git-send-email-pbonzini@redhat.com> References: <1379340373-5135-1-git-send-email-pbonzini@redhat.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 6348 Lines: 202 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: stable@vger.kernel.org Cc: kvm@vger.kernel.org Cc: gleb@redhat.com Cc: jan.kiszka@siemens.com Signed-off-by: Paolo Bonzini --- Documentation/virtual/kvm/locking.txt | 2 +- arch/x86/kvm/mmu.c | 4 ++-- arch/x86/kvm/x86.c | 8 ++++---- include/linux/kvm_host.h | 2 +- virt/kvm/kvm_main.c | 18 +++++++++--------- 5 files changed, 17 insertions(+), 17 deletions(-) diff --git a/Documentation/virtual/kvm/locking.txt b/Documentation/virtual/kvm/locking.txt index ba9e1c2..f886941 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 6e2d2c8..d027a72 100644 --- a/arch/x86/kvm/mmu.c +++ b/arch/x86/kvm/mmu.c @@ -4429,7 +4429,7 @@ 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; @@ -4473,7 +4473,7 @@ unlock: 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 7c36099..3acd631 100644 --- a/arch/x86/kvm/x86.c +++ b/arch/x86/kvm/x86.c @@ -5273,7 +5273,7 @@ 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) @@ -5283,7 +5283,7 @@ 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) { /* @@ -5436,12 +5436,12 @@ 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 749bdb1..7c961e1 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 da13379..3397a9c 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]); @@ -3057,10 +3057,10 @@ 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; } @@ -3074,12 +3074,12 @@ 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; } -- 1.8.3.1 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/