The branch main has been updated by markj:
URL:
https://cgit.FreeBSD.org/src/commit/?id=34fac29e98313fb0bfba0503e2e19e352b452516
commit 34fac29e98313fb0bfba0503e2e19e352b452516
Author: Mark Johnston <ma...@freebsd.org>
AuthorDate: 2021-10-20 00:29:18 +0000
Commit: Mark Johnston <ma...@freebsd.org>
CommitDate: 2021-10-20 01:22:57 +0000
amd64: Add comments to pmap_pinit_type()
... explaining why we don't pass the pmap pointer to
pmap_alloc_pt_page().
Reported by: alc
Reviewed by: alc, kib
MFC after: 1 week
Sponsored by: The FreeBSD Foundation
Differential Revision: https://reviews.freebsd.org/D32528
---
sys/amd64/amd64/pmap.c | 8 +++++++-
1 file changed, 7 insertions(+), 1 deletion(-)
diff --git a/sys/amd64/amd64/pmap.c b/sys/amd64/amd64/pmap.c
index 8d6379ab170c..66d7ac6669da 100644
--- a/sys/amd64/amd64/pmap.c
+++ b/sys/amd64/amd64/pmap.c
@@ -4345,7 +4345,9 @@ pmap_pinit_type(pmap_t pmap, enum pmap_type pm_type, int
flags)
int i;
/*
- * allocate the page directory page
+ * Allocate the page directory page. Pass NULL instead of a pointer to
+ * the pmap here to avoid recording this page in the resident count, as
+ * optimizations in pmap_remove() depend on this.
*/
pmltop_pg = pmap_alloc_pt_page(NULL, 0, VM_ALLOC_WIRED | VM_ALLOC_ZERO |
VM_ALLOC_WAITOK);
@@ -4377,6 +4379,10 @@ pmap_pinit_type(pmap_t pmap, enum pmap_type pm_type, int
flags)
else
pmap_pinit_pml4(pmltop_pg);
if ((curproc->p_md.md_flags & P_MD_KPTI) != 0) {
+ /*
+ * As with pmltop_pg, pass NULL instead of a pointer to
+ * the pmap to ensure that the PTI page isn't counted.
+ */
pmltop_pgu = pmap_alloc_pt_page(NULL, 0,
VM_ALLOC_WIRED | VM_ALLOC_WAITOK);
pmap->pm_pmltopu = (pml4_entry_t *)PHYS_TO_DMAP(
