Author: jeff Date: Sun Dec 15 02:02:27 2019 New Revision: 355764 URL: https://svnweb.freebsd.org/changeset/base/355764
Log: Slightly optimize locking in vm_map_copy_swap_entry(). Anonymous objects require the object lock to synchronize collapse. Other swap objects such as tmpfs do not. Reported by: mjg Reviewed by: kib, markj Differential Revision: https://reviews.freebsd.org/D22747 Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Sun Dec 15 02:00:32 2019 (r355763) +++ head/sys/vm/vm_map.c Sun Dec 15 02:02:27 2019 (r355764) @@ -3870,15 +3870,19 @@ vm_map_copy_swap_object(vm_map_entry_t src_entry, vm_m int charged; src_object = src_entry->object.vm_object; - VM_OBJECT_WLOCK(src_object); charged = ENTRY_CHARGED(src_entry); - vm_object_collapse(src_object); - if ((src_object->flags & OBJ_ONEMAPPING) != 0) { - vm_object_split(src_entry); - src_object = src_entry->object.vm_object; - } - vm_object_reference_locked(src_object); - vm_object_clear_flag(src_object, OBJ_ONEMAPPING); + if ((src_object->flags & OBJ_ANON) != 0) { + VM_OBJECT_WLOCK(src_object); + vm_object_collapse(src_object); + if ((src_object->flags & OBJ_ONEMAPPING) != 0) { + vm_object_split(src_entry); + src_object = src_entry->object.vm_object; + } + vm_object_reference_locked(src_object); + vm_object_clear_flag(src_object, OBJ_ONEMAPPING); + VM_OBJECT_WUNLOCK(src_object); + } else + vm_object_reference(src_object); if (src_entry->cred != NULL && !(src_entry->eflags & MAP_ENTRY_NEEDS_COPY)) { KASSERT(src_object->cred == NULL, @@ -3887,7 +3891,6 @@ vm_map_copy_swap_object(vm_map_entry_t src_entry, vm_m src_object->cred = src_entry->cred; src_object->charge = size; } - VM_OBJECT_WUNLOCK(src_object); dst_entry->object.vm_object = src_object; if (charged) { cred = curthread->td_ucred; _______________________________________________ svn-src-head@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-head To unsubscribe, send any mail to "svn-src-head-unsubscr...@freebsd.org"
