diff options
Diffstat (limited to 'sys/vm/vm_page.c')
| -rw-r--r-- | sys/vm/vm_page.c | 24 |
1 files changed, 22 insertions, 2 deletions
diff --git a/sys/vm/vm_page.c b/sys/vm/vm_page.c index d4a7ba5..947e5d4 100644 --- a/sys/vm/vm_page.c +++ b/sys/vm/vm_page.c @@ -1697,6 +1697,14 @@ vm_page_test_dirty(vm_page_t m) int so_zerocp_fullpage = 0; +/* + * Replace the given page with a copy. The copied page assumes + * the portion of the given page's "wire_count" that is not the + * responsibility of this copy-on-write mechanism. + * + * The object containing the given page must have a non-zero + * paging-in-progress count and be locked. + */ void vm_page_cowfault(vm_page_t m) { @@ -1705,6 +1713,10 @@ vm_page_cowfault(vm_page_t m) vm_pindex_t pindex; object = m->object; + VM_OBJECT_LOCK_ASSERT(object, MA_OWNED); + KASSERT(object->paging_in_progress != 0, + ("vm_page_cowfault: object %p's paging-in-progress count is zero.", + object)); pindex = m->pindex; retry_alloc: @@ -1717,8 +1729,16 @@ vm_page_cowfault(vm_page_t m) VM_OBJECT_UNLOCK(object); VM_WAIT; VM_OBJECT_LOCK(object); - vm_page_lock_queues(); - goto retry_alloc; + if (m == vm_page_lookup(object, pindex)) { + vm_page_lock_queues(); + goto retry_alloc; + } else { + /* + * Page disappeared during the wait. + */ + vm_page_lock_queues(); + return; + } } if (m->cow == 0) { |
