git: bb150039c0ce - releng/15.0 - vm_fault: only rely on PG_ZERO when the page was newly allocated

The branch releng/15.0 has been updated by markj:

URL: https://cgit.FreeBSD.org/src/commit/?id=bb150039c0ce2de8704d67b104beb306482c3cb2

commit bb150039c0ce2de8704d67b104beb306482c3cb2
Author:     Konstantin Belousov <kib@FreeBSD.org>
AuthorDate: 2025-11-28 15:57:22 +0000
Commit:     Mark Johnston <markj@FreeBSD.org>
CommitDate: 2026-01-26 16:48:40 +0000

    vm_fault: only rely on PG_ZERO when the page was newly allocated
    
    Approved by:    so
    Security:       FreeBSD-EN-26:03.vm
    
    (cherry picked from commit cff67bc43df14d492ccc08ec92fddceadd069953)
    (cherry picked from commit 3c0942f99209cb95be64c95322b5f99b575db6b3)
---
 sys/vm/vm_fault.c | 6 +++++-
 1 file changed, 5 insertions(+), 1 deletion(-)

diff --git a/sys/vm/vm_fault.c b/sys/vm/vm_fault.c
index 22558a12b44b..f9711548e23e 100644
--- a/sys/vm/vm_fault.c
+++ b/sys/vm/vm_fault.c
@@ -138,6 +138,7 @@ struct faultstate {
 	vm_object_t	object;
 	vm_pindex_t	pindex;
 	vm_page_t	m;
+	bool		m_needs_zeroing;
 
 	/* Top-level map object. */
 	vm_object_t	first_object;
@@ -264,6 +265,7 @@ static void
 vm_fault_deallocate(struct faultstate *fs)
 {
 
+	fs->m_needs_zeroing = true;
 	vm_fault_page_release(&fs->m_cow);
 	vm_fault_page_release(&fs->m);
 	vm_object_pip_wakeup(fs->object);
@@ -1181,7 +1183,7 @@ vm_fault_zerofill(struct faultstate *fs)
 	/*
 	 * Zero the page if necessary and mark it valid.
 	 */
-	if ((fs->m->flags & PG_ZERO) == 0) {
+	if (fs->m_needs_zeroing) {
 		pmap_zero_page(fs->m);
 	} else {
 		VM_CNT_INC(v_ozfod);
@@ -1296,6 +1298,7 @@ vm_fault_allocate(struct faultstate *fs, struct pctrie_iter *pages)
 			vm_waitpfault(dset, vm_pfault_oom_wait * hz);
 		return (FAULT_RESTART);
 	}
+	fs->m_needs_zeroing = (fs->m->flags & PG_ZERO) == 0;
 	fs->oom_started = false;
 
 	return (FAULT_CONTINUE);
@@ -1586,6 +1589,7 @@ vm_fault(vm_map_t map, vm_offset_t vaddr, vm_prot_t fault_type,
 	fs.fault_flags = fault_flags;
 	fs.map = map;
 	fs.lookup_still_valid = false;
+	fs.m_needs_zeroing = true;
 	fs.oom_started = false;
 	fs.nera = -1;
 	fs.can_read_lock = true;