To date, unwiring a fictitious page has produced a panic. The reason
being that PHYS_TO_VM_PAGE() returns the wrong vm_page for fictitious pages but unwiring uses PHYS_TO_VM_PAGE(). The resulting panic reported an unexpected wired count. Rather than attempting to fix PHYS_TO_VM_PAGE(), this fix takes advantage of the properties of fictitious pages. Specifically, fictitious pages will never be completely unwired. Therefore, we can keep a fictitious page's wired count forever set to one and thereby avoid the use of PHYS_TO_VM_PAGE() when we know that we're working with a fictitious page, just not which one. In collaboration with: green@, tegge@ PR: kern/29915
This commit is contained in:
parent
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Notes:
svn2git
2020-12-20 02:59:44 +00:00
svn path=/head/; revision=129571
@ -69,8 +69,8 @@ void swapout_procs(int);
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int useracc(void *, int, int);
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int vm_fault(vm_map_t, vm_offset_t, vm_prot_t, int);
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void vm_fault_copy_entry(vm_map_t, vm_map_t, vm_map_entry_t, vm_map_entry_t);
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void vm_fault_unwire(vm_map_t, vm_offset_t, vm_offset_t);
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int vm_fault_wire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
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void vm_fault_unwire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t);
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int vm_fault_wire(vm_map_t, vm_offset_t, vm_offset_t, boolean_t, boolean_t);
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void vm_forkproc(struct thread *, struct proc *, struct thread *, int);
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void vm_waitproc(struct proc *);
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int vm_mmap(vm_map_t, vm_offset_t *, vm_size_t, vm_prot_t, vm_prot_t, int, void *, vm_ooffset_t);
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@ -1038,10 +1038,8 @@ vm_fault_quick(caddr_t v, int prot)
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* Wire down a range of virtual addresses in a map.
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*/
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int
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vm_fault_wire(map, start, end, user_wire)
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vm_map_t map;
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vm_offset_t start, end;
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boolean_t user_wire;
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vm_fault_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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boolean_t user_wire, boolean_t fictitious)
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{
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vm_offset_t va;
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int rv;
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@ -1057,7 +1055,7 @@ vm_fault_wire(map, start, end, user_wire)
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user_wire ? VM_FAULT_USER_WIRE : VM_FAULT_CHANGE_WIRING);
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if (rv) {
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if (va != start)
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vm_fault_unwire(map, start, va);
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vm_fault_unwire(map, start, va, fictitious);
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return (rv);
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}
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}
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@ -1070,9 +1068,8 @@ vm_fault_wire(map, start, end, user_wire)
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* Unwire a range of virtual addresses in a map.
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*/
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void
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vm_fault_unwire(map, start, end)
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vm_map_t map;
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vm_offset_t start, end;
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vm_fault_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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boolean_t fictitious)
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{
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vm_paddr_t pa;
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vm_offset_t va;
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@ -1090,9 +1087,11 @@ vm_fault_unwire(map, start, end)
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pa = pmap_extract(pmap, va);
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if (pa != 0) {
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pmap_change_wiring(pmap, va, FALSE);
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vm_page_lock_queues();
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vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
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vm_page_unlock_queues();
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if (!fictitious) {
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vm_page_lock_queues();
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vm_page_unwire(PHYS_TO_VM_PAGE(pa), 1);
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vm_page_unlock_queues();
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}
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}
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}
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if (pmap != kernel_pmap)
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@ -1726,7 +1726,9 @@ vm_map_unwire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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/*
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* Retain the map lock.
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*/
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vm_fault_unwire(map, entry->start, entry->end);
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vm_fault_unwire(map, entry->start, entry->end,
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entry->object.vm_object != NULL &&
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entry->object.vm_object->type == OBJT_DEVICE);
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}
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}
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KASSERT(entry->eflags & MAP_ENTRY_IN_TRANSITION,
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@ -1758,7 +1760,7 @@ vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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vm_offset_t saved_end, saved_start;
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unsigned int last_timestamp;
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int rv;
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boolean_t need_wakeup, result, user_wire;
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boolean_t fictitious, need_wakeup, result, user_wire;
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user_wire = (flags & VM_MAP_WIRE_USER) ? TRUE : FALSE;
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vm_map_lock(map);
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@ -1834,13 +1836,15 @@ vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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entry->wired_count++;
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saved_start = entry->start;
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saved_end = entry->end;
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fictitious = entry->object.vm_object != NULL &&
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entry->object.vm_object->type == OBJT_DEVICE;
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/*
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* Release the map lock, relying on the in-transition
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* mark.
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*/
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vm_map_unlock(map);
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rv = vm_fault_wire(map, saved_start, saved_end,
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user_wire);
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user_wire, fictitious);
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vm_map_lock(map);
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if (last_timestamp + 1 != map->timestamp) {
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/*
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@ -1924,7 +1928,9 @@ vm_map_wire(vm_map_t map, vm_offset_t start, vm_offset_t end,
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/*
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* Retain the map lock.
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*/
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vm_fault_unwire(map, entry->start, entry->end);
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vm_fault_unwire(map, entry->start, entry->end,
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entry->object.vm_object != NULL &&
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entry->object.vm_object->type == OBJT_DEVICE);
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}
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}
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KASSERT(entry->eflags & MAP_ENTRY_IN_TRANSITION,
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@ -2048,7 +2054,9 @@ vm_map_sync(
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static void
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vm_map_entry_unwire(vm_map_t map, vm_map_entry_t entry)
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{
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vm_fault_unwire(map, entry->start, entry->end);
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vm_fault_unwire(map, entry->start, entry->end,
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entry->object.vm_object != NULL &&
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entry->object.vm_object->type == OBJT_DEVICE);
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entry->wired_count = 0;
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}
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@ -1167,6 +1167,8 @@ vm_page_wire(vm_page_t m)
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*/
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s = splvm();
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mtx_assert(&vm_page_queue_mtx, MA_OWNED);
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if (m->flags & PG_FICTITIOUS)
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return;
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if (m->wire_count == 0) {
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if ((m->flags & PG_UNMANAGED) == 0)
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vm_pageq_remove(m);
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@ -1212,6 +1214,8 @@ vm_page_unwire(vm_page_t m, int activate)
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s = splvm();
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mtx_assert(&vm_page_queue_mtx, MA_OWNED);
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if (m->flags & PG_FICTITIOUS)
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return;
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if (m->wire_count > 0) {
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m->wire_count--;
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if (m->wire_count == 0) {
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