diff --git a/arch/s390/kvm/vsie.c b/arch/s390/kvm/vsie.c index d90c818a9ae712e2378822e0e9fb0dc9eff6f770..30e22aa9415c07724a0d5de04993b56d6852098d 100644 --- a/arch/s390/kvm/vsie.c +++ b/arch/s390/kvm/vsie.c @@ -1331,8 +1331,14 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) page = radix_tree_lookup(&kvm->arch.vsie.addr_to_page, addr >> 9); rcu_read_unlock(); if (page) { - if (page_ref_inc_return(page) == 2) - return page_to_virt(page); + if (page_ref_inc_return(page) == 2) { + if (page->index == addr) + return page_to_virt(page); + /* + * We raced with someone reusing + putting this vsie + * page before we grabbed it. + */ + } page_ref_dec(page); } @@ -1362,15 +1368,20 @@ static struct vsie_page *get_vsie_page(struct kvm *kvm, unsigned long addr) kvm->arch.vsie.next++; kvm->arch.vsie.next %= nr_vcpus; } - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); + if (page->index != ULONG_MAX) + radix_tree_delete(&kvm->arch.vsie.addr_to_page, + page->index >> 9); } - page->index = addr; - /* double use of the same address */ + /* Mark it as invalid until it resides in the tree. */ + page->index = ULONG_MAX; + + /* Double use of the same address or allocation failure. */ if (radix_tree_insert(&kvm->arch.vsie.addr_to_page, addr >> 9, page)) { page_ref_dec(page); mutex_unlock(&kvm->arch.vsie.mutex); return NULL; } + page->index = addr; mutex_unlock(&kvm->arch.vsie.mutex); vsie_page = page_to_virt(page); @@ -1463,7 +1474,9 @@ void kvm_s390_vsie_destroy(struct kvm *kvm) vsie_page = page_to_virt(page); release_gmap_shadow(vsie_page); /* free the radix tree entry */ - radix_tree_delete(&kvm->arch.vsie.addr_to_page, page->index >> 9); + if (page->index != ULONG_MAX) + radix_tree_delete(&kvm->arch.vsie.addr_to_page, + page->index >> 9); __free_page(page); } kvm->arch.vsie.page_count = 0;