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| author | Oleg Nesterov <oleg@redhat.com> | 2014-04-21 15:26:01 +0200 |
|---|---|---|
| committer | Ben Hutchings <ben@decadent.org.uk> | 2014-06-09 13:29:03 +0100 |
| commit | 0e40d9cf4b9c34971ab42afbe2cb52fa0c6f0cd1 (patch) | |
| tree | fe53ee04391f676a23dbf1c0e1fdb3367b3fc24d /virt | |
| parent | d244fc2319deec77099d7b4d63d8fe8830ac66ec (diff) | |
| download | lwn-0e40d9cf4b9c34971ab42afbe2cb52fa0c6f0cd1.tar.gz lwn-0e40d9cf4b9c34971ab42afbe2cb52fa0c6f0cd1.zip | |
KVM: async_pf: mm->mm_users can not pin apf->mm
commit 41c22f626254b9dc0376928cae009e73d1b6a49a upstream.
get_user_pages(mm) is simply wrong if mm->mm_users == 0 and exit_mmap/etc
was already called (or is in progress), mm->mm_count can only pin mm->pgd
and mm_struct itself.
Change kvm_setup_async_pf/async_pf_execute to inc/dec mm->mm_users.
kvm_create_vm/kvm_destroy_vm play with ->mm_count too but this case looks
fine at first glance, it seems that this ->mm is only used to verify that
current->mm == kvm->mm.
Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Paolo Bonzini <pbonzini@redhat.com>
Signed-off-by: Ben Hutchings <ben@decadent.org.uk>
Diffstat (limited to 'virt')
| -rw-r--r-- | virt/kvm/async_pf.c | 8 |
1 files changed, 4 insertions, 4 deletions
diff --git a/virt/kvm/async_pf.c b/virt/kvm/async_pf.c index 68dc92421c8d..bdd2c0d690d6 100644 --- a/virt/kvm/async_pf.c +++ b/virt/kvm/async_pf.c @@ -87,7 +87,7 @@ static void async_pf_execute(struct work_struct *work) if (waitqueue_active(&vcpu->wq)) wake_up_interruptible(&vcpu->wq); - mmdrop(mm); + mmput(mm); kvm_put_kvm(vcpu->kvm); } @@ -100,7 +100,7 @@ void kvm_clear_async_pf_completion_queue(struct kvm_vcpu *vcpu) typeof(*work), queue); list_del(&work->queue); if (cancel_work_sync(&work->work)) { - mmdrop(work->mm); + mmput(work->mm); kvm_put_kvm(vcpu->kvm); /* == work->vcpu->kvm */ kmem_cache_free(async_pf_cache, work); } @@ -169,7 +169,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, work->addr = gfn_to_hva(vcpu->kvm, gfn); work->arch = *arch; work->mm = current->mm; - atomic_inc(&work->mm->mm_count); + atomic_inc(&work->mm->mm_users); kvm_get_kvm(work->vcpu->kvm); /* this can't really happen otherwise gfn_to_pfn_async @@ -187,7 +187,7 @@ int kvm_setup_async_pf(struct kvm_vcpu *vcpu, gva_t gva, gfn_t gfn, return 1; retry_sync: kvm_put_kvm(work->vcpu->kvm); - mmdrop(work->mm); + mmput(work->mm); kmem_cache_free(async_pf_cache, work); return 0; } |