diff options
| -rw-r--r-- | sys/vm/vm_object.c | 36 |
1 files changed, 25 insertions, 11 deletions
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c index 5000db4..5321b53 100644 --- a/sys/vm/vm_object.c +++ b/sys/vm/vm_object.c @@ -438,23 +438,37 @@ vm_object_deallocate(vm_object_t object) while (object != NULL) { int vfslocked; - /* - * In general, the object should be locked when working with - * its type. In this case, in order to maintain proper lock - * ordering, an exception is possible because a vnode-backed - * object never changes its type. - */ + vfslocked = 0; - if (object->type == OBJT_VNODE) { - struct vnode *vp = (struct vnode *) object->handle; - vfslocked = VFS_LOCK_GIANT(vp->v_mount); - } + restart: VM_OBJECT_LOCK(object); if (object->type == OBJT_VNODE) { + struct vnode *vp = (struct vnode *) object->handle; + + /* + * Conditionally acquire Giant for a vnode-backed + * object. We have to be careful since the type of + * a vnode object can change while the object is + * unlocked. + */ + if (VFS_NEEDSGIANT(vp->v_mount) && !vfslocked) { + vfslocked = 1; + if (!mtx_trylock(&Giant)) { + VM_OBJECT_UNLOCK(object); + mtx_lock(&Giant); + goto restart; + } + } vm_object_vndeallocate(object); VFS_UNLOCK_GIANT(vfslocked); return; - } + } else + /* + * This is to handle the case that the object + * changed type while we dropped its lock to + * obtain Giant. + */ + VFS_UNLOCK_GIANT(vfslocked); KASSERT(object->ref_count != 0, ("vm_object_deallocate: object deallocated too many times: %d", object->type)); |
