Author: markj Date: Thu Jan 23 16:45:10 2020 New Revision: 357052 URL: https://svnweb.freebsd.org/changeset/base/357052
Log: vm_map_submap(): Avoid unnecessary clipping. A submap can only be created from an entry spanning the entire request range. In particular, if vm_map_lookup_entry() returns false or the returned entry contains "end". Since the only use of submaps in FreeBSD is for the static pipe and execve argument KVA maps, this has no functional effect. Github PR: https://github.com/freebsd/freebsd/pull/420 Submitted by: Wuyang Chung <wuyang.chu...@gmail.com> (original) Reviewed by: dougm, kib MFC after: 1 week Differential Revision: https://reviews.freebsd.org/D23299 Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Thu Jan 23 16:36:58 2020 (r357051) +++ head/sys/vm/vm_map.c Thu Jan 23 16:45:10 2020 (r357052) @@ -2477,19 +2477,12 @@ vm_map_submap( vm_map_unlock(submap); vm_map_lock(map); - VM_MAP_RANGE_CHECK(map, start, end); - - if (vm_map_lookup_entry(map, start, &entry)) { + if (vm_map_lookup_entry(map, start, &entry) && entry->end >= end && + (entry->eflags & MAP_ENTRY_COW) == 0 && + entry->object.vm_object == NULL) { vm_map_clip_start(map, entry, start); - } else - entry = vm_map_entry_succ(entry); - - vm_map_clip_end(map, entry, end); - - if ((entry->start == start) && (entry->end == end) && - ((entry->eflags & MAP_ENTRY_COW) == 0) && - (entry->object.vm_object == NULL)) { + vm_map_clip_end(map, entry, end); entry->object.sub_map = submap; entry->eflags |= MAP_ENTRY_IS_SUB_MAP; result = KERN_SUCCESS; _______________________________________________ svn-src-all@freebsd.org mailing list https://lists.freebsd.org/mailman/listinfo/svn-src-all To unsubscribe, send any mail to "svn-src-all-unsubscr...@freebsd.org"
