System maps are prohibited from mapping vnode-backed objects. Take
advantage of this restriction to avoid acquiring and releasing Giant when wiring pages within a system map. In collaboration with: tegge@
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parent
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commit
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=135088
@ -172,7 +172,7 @@ _unlock_things(struct faultstate *fs, int dealloc)
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mtx_unlock(&Giant);
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fs->vp = NULL;
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}
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if (dealloc)
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if (dealloc && !fs->map->system_map)
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VM_UNLOCK_GIANT();
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}
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@ -291,11 +291,14 @@ RetryFault:;
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*
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* XXX vnode_pager_lock() can block without releasing the map lock.
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*/
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mtx_lock(&Giant);
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if (!fs.map->system_map)
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mtx_lock(&Giant);
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VM_OBJECT_LOCK(fs.first_object);
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vm_object_reference_locked(fs.first_object);
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fs.vp = vnode_pager_lock(fs.first_object);
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if (debug_mpsafevm)
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KASSERT(fs.vp == NULL || !fs.map->system_map,
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("vm_fault: vnode-backed object mapped by system map"));
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if (debug_mpsafevm && !fs.map->system_map)
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mtx_unlock(&Giant);
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vm_object_pip_add(fs.first_object, 1);
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@ -369,7 +372,8 @@ RetryFault:;
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if (!vm_page_sleep_if_busy(fs.m, TRUE, "vmpfw"))
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vm_page_unlock_queues();
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atomic_add_int(&cnt.v_intrans, 1);
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VM_UNLOCK_GIANT();
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if (!fs.map->system_map)
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VM_UNLOCK_GIANT();
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vm_object_deallocate(fs.first_object);
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goto RetryFault;
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}
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@ -1026,13 +1030,9 @@ vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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* read-only sections.
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*/
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for (va = start; va < end; va += PAGE_SIZE) {
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if (map->system_map)
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mtx_lock(&Giant);
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rv = vm_fault(map, va,
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user_wire ? VM_PROT_READ : VM_PROT_READ | VM_PROT_WRITE,
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user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING);
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if (map->system_map)
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mtx_unlock(&Giant);
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if (rv) {
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if (va != start)
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vm_fault_unwire(map, start, va, fictitious);
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