Author: jeff Date: Mon Nov 25 07:13:05 2019 New Revision: 355082 URL: https://svnweb.freebsd.org/changeset/base/355082
Log: Move anonymous object copying for fork into its own routine and so that we can avoid locking non-anonymous objects. Reviewed by: kib Differential Revision: https://reviews.freebsd.org/D22472 Modified: head/sys/vm/vm_map.c Modified: head/sys/vm/vm_map.c ============================================================================== --- head/sys/vm/vm_map.c Mon Nov 25 06:16:53 2019 (r355081) +++ head/sys/vm/vm_map.c Mon Nov 25 07:13:05 2019 (r355082) @@ -3722,7 +3722,57 @@ vm_map_check_protection(vm_map_t map, vm_offset_t star return (TRUE); } + /* + * + * vm_map_copy_anon_object: + * + * Copies an anonymous object from an existing map entry to a + * new one. Carries forward the swap charge. May change the + * src object on return. + */ +static void +vm_map_copy_anon_object(vm_map_entry_t src_entry, vm_map_entry_t dst_entry, + vm_offset_t size, vm_ooffset_t *fork_charge) +{ + vm_object_t src_object; + struct ucred *cred; + 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_entry->cred != NULL && + !(src_entry->eflags & MAP_ENTRY_NEEDS_COPY)) { + KASSERT(src_object->cred == NULL, + ("OVERCOMMIT: vm_map_copy_anon_entry: cred %p", + src_object)); + 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; + crhold(cred); + dst_entry->cred = cred; + *fork_charge += size; + if (!(src_entry->eflags & MAP_ENTRY_NEEDS_COPY)) { + crhold(cred); + src_entry->cred = cred; + *fork_charge += size; + } + } +} + +/* * vm_map_copy_entry: * * Copies the contents of the source entry to the destination @@ -3739,8 +3789,6 @@ vm_map_copy_entry( vm_object_t src_object; vm_map_entry_t fake_entry; vm_offset_t size; - struct ucred *cred; - int charged; VM_MAP_ASSERT_LOCKED(dst_map); @@ -3766,39 +3814,14 @@ vm_map_copy_entry( */ size = src_entry->end - src_entry->start; if ((src_object = src_entry->object.vm_object) != NULL) { - VM_OBJECT_WLOCK(src_object); - charged = ENTRY_CHARGED(src_entry); if ((src_object->flags & OBJ_ANON) != 0) { - 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_entry->cred != NULL && - !(src_entry->eflags & MAP_ENTRY_NEEDS_COPY)) { - KASSERT(src_object->cred == NULL, - ("OVERCOMMIT: vm_map_copy_entry: cred %p", - src_object)); - 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; - crhold(cred); - dst_entry->cred = cred; - *fork_charge += size; - if (!(src_entry->eflags & - MAP_ENTRY_NEEDS_COPY)) { - crhold(cred); - src_entry->cred = cred; - *fork_charge += size; - } + vm_map_copy_anon_object(src_entry, dst_entry, + size, fork_charge); + /* May have split/collapsed, reload obj. */ + src_object = src_entry->object.vm_object; + } else { + vm_object_reference(src_object); + dst_entry->object.vm_object = src_object; } src_entry->eflags |= MAP_ENTRY_COW | MAP_ENTRY_NEEDS_COPY; _______________________________________________ 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"
