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 99f641267d449f26a2e13449964f29d17897c29f)
This commit is contained in:
Konstantin Belousov 2025-11-28 17:57:22 +02:00 committed by Franco Fichtner
parent 8137bf0efa
commit 0a4a1c0165

View file

@ -139,6 +139,7 @@ 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;
@ -265,6 +266,7 @@ 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);
@ -1172,7 +1174,7 @@ 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);
@ -1286,6 +1288,7 @@ vm_fault_allocate(struct faultstate *fs)
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);
@ -1553,6 +1556,7 @@ 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;