git: c6c63b92effd - main - vm_object: don't reset new iterator

The branch main has been updated by dougm:

URL: https://cgit.FreeBSD.org/src/commit/?id=c6c63b92effd6d0662977f11bf429127b9dc4407

commit c6c63b92effd6d0662977f11bf429127b9dc4407
Author:     Doug Moore <dougm@FreeBSD.org>
AuthorDate: 2025-03-04 05:31:18 +0000
Commit:     Doug Moore <dougm@FreeBSD.org>
CommitDate: 2025-03-04 05:31:18 +0000

    vm_object: don't reset new iterator
    
    Don't call pctrie_iter_reset on a just-initialized iterator. Let the
    code jumping back up do the resetting.  Add an assertion at the jump destination to check that a reset happened.
    
    Reviewed by:    kib
    Differential Revision:  https://reviews.freebsd.org/D49207
---
 sys/sys/pctrie.h      | 6 ++++++
 sys/vm/device_pager.c | 2 ++
 sys/vm/vm_object.c    | 9 +++++++--
 3 files changed, 15 insertions(+), 2 deletions(-)

diff --git a/sys/sys/pctrie.h b/sys/sys/pctrie.h
index 42473dc8e632..dac18b58498b 100644
--- a/sys/sys/pctrie.h
+++ b/sys/sys/pctrie.h
@@ -47,6 +47,12 @@ pctrie_iter_reset(struct pctrie_iter *it)
 	it->node = NULL;
 }
 
+static __inline bool
+pctrie_iter_is_reset(struct pctrie_iter *it)
+{
+	return (it->node == NULL);
+}
+
 static __inline void
 pctrie_iter_init(struct pctrie_iter *it, struct pctrie *ptree)
 {
diff --git a/sys/vm/device_pager.c b/sys/vm/device_pager.c
index 0691d43a5946..0b3a2eb54d75 100644
--- a/sys/vm/device_pager.c
+++ b/sys/vm/device_pager.c
@@ -293,6 +293,8 @@ cdev_mgtdev_pager_free_pages(vm_object_t object)
 	vm_page_iter_init(&pages, object);
 	VM_OBJECT_WLOCK(object);
 retry:
+	KASSERT(pctrie_iter_is_reset(&pages),
+	    ("%s: pctrie_iter not reset for retry", __func__));
 	for (m = vm_radix_iter_lookup_ge(&pages, 0); m != NULL;
 	    m = vm_radix_iter_step(&pages)) {
 		if (!vm_page_busy_acquire(m, VM_ALLOC_WAITFAIL)) {
diff --git a/sys/vm/vm_object.c b/sys/vm/vm_object.c
index 9269103d8d91..79a28c4d77b0 100644
--- a/sys/vm/vm_object.c
+++ b/sys/vm/vm_object.c
@@ -1576,7 +1576,8 @@ vm_object_split(vm_map_entry_t entry)
 	vm_object_set_flag(orig_object, OBJ_SPLIT);
 	vm_page_iter_limit_init(&pages, orig_object, offidxstart + size);
 retry:
-	pctrie_iter_reset(&pages);
+	KASSERT(pctrie_iter_is_reset(&pages),
+	    ("%s: pctrie_iter not reset for retry", __func__));
 	for (m = vm_radix_iter_lookup_ge(&pages, offidxstart); m != NULL;
 	    m = vm_radix_iter_step(&pages)) {
 		/*
@@ -1590,6 +1591,7 @@ retry:
 			VM_OBJECT_WUNLOCK(new_object);
 			if (vm_page_busy_sleep(m, "spltwt", 0))
 				VM_OBJECT_WLOCK(orig_object);
+			pctrie_iter_reset(&pages);
 			VM_OBJECT_WLOCK(new_object);
 			goto retry;
 		}
@@ -1611,6 +1613,7 @@ retry:
 			VM_OBJECT_WUNLOCK(new_object);
 			VM_OBJECT_WUNLOCK(orig_object);
 			vm_radix_wait();
+			pctrie_iter_reset(&pages);
 			VM_OBJECT_WLOCK(orig_object);
 			VM_OBJECT_WLOCK(new_object);
 			goto retry;
@@ -1996,7 +1999,8 @@ vm_object_page_remove(vm_object_t object, vm_pindex_t start, vm_pindex_t end,
 	vm_object_pip_add(object, 1);
 	vm_page_iter_limit_init(&pages, object, end);
 again:
-	pctrie_iter_reset(&pages);
+	KASSERT(pctrie_iter_is_reset(&pages),
+	    ("%s: pctrie_iter not reset for retry", __func__));
 	for (p = vm_radix_iter_lookup_ge(&pages, start); p != NULL;
 	     p = vm_radix_iter_step(&pages)) {
 		/*
@@ -2025,6 +2029,7 @@ again:
 		if (vm_page_tryxbusy(p) == 0) {
 			if (vm_page_busy_sleep(p, "vmopar", 0))
 				VM_OBJECT_WLOCK(object);
+			pctrie_iter_reset(&pages);
 			goto again;
 		}
 		if ((options & OBJPR_VALIDONLY) != 0 && vm_page_none_valid(p)) {