Module Name: src
Committed By: riastradh
Date: Sat Jun 4 20:54:24 UTC 2022
Modified Files:
src/sys/uvm: uvm_map.c
Log Message:
uvm(9): Fix 19-year-old bug in assertion about mmap hint.
Previously this would _first_ remember the original hint, and _then_
clamp the hint to the VM map's range:
orig_hint = hint;
if (hint < vm_map_min(map)) { /* check ranges ... */
if (flags & UVM_FLAG_FIXED) {
UVMHIST_LOG(maphist,"<- VA below map range",0,0,0,0);
return (NULL);
}
hint = vm_map_min(map);
...
KASSERTMSG(!topdown || hint <= orig_hint, "hint: %#jx, orig_hint: %#jx",
(uintmax_t)hint, (uintmax_t)orig_hint);
Even if nothing else happens in the ellipsis, taking the branch
guarantees the assertion will fail in the topdown case.
To generate a diff of this commit:
cvs rdiff -u -r1.394 -r1.395 src/sys/uvm/uvm_map.c
Please note that diffs are not public domain; they are subject to the
copyright notices on the relevant files.
Modified files:
Index: src/sys/uvm/uvm_map.c
diff -u src/sys/uvm/uvm_map.c:1.394 src/sys/uvm/uvm_map.c:1.395
--- src/sys/uvm/uvm_map.c:1.394 Sun Apr 10 09:50:46 2022
+++ src/sys/uvm/uvm_map.c Sat Jun 4 20:54:24 2022
@@ -1,4 +1,4 @@
-/* $NetBSD: uvm_map.c,v 1.394 2022/04/10 09:50:46 andvar Exp $ */
+/* $NetBSD: uvm_map.c,v 1.395 2022/06/04 20:54:24 riastradh Exp $ */
/*
* Copyright (c) 1997 Charles D. Cranor and Washington University.
@@ -66,7 +66,7 @@
*/
#include <sys/cdefs.h>
-__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.394 2022/04/10 09:50:46 andvar Exp $");
+__KERNEL_RCSID(0, "$NetBSD: uvm_map.c,v 1.395 2022/06/04 20:54:24 riastradh Exp $");
#include "opt_ddb.h"
#include "opt_pax.h"
@@ -1813,12 +1813,17 @@ uvm_map_findspace(struct vm_map *map, va
uvm_map_check(map, "map_findspace entry");
/*
- * remember the original hint. if we are aligning, then we
- * may have to try again with no alignment constraint if
- * we fail the first time.
+ * Clamp the hint to the VM map's min/max address, and remmeber
+ * the clamped original hint. Remember the original hint,
+ * clamped to the min/max address. If we are aligning, then we
+ * may have to try again with no alignment constraint if we
+ * fail the first time.
+ *
+ * We use the original hint to verify later that the search has
+ * been monotonic -- that is, nonincreasing or nondecreasing,
+ * according to topdown or !topdown respectively. But the
+ * clamping is not monotonic.
*/
-
- orig_hint = hint;
if (hint < vm_map_min(map)) { /* check ranges ... */
if (flags & UVM_FLAG_FIXED) {
UVMHIST_LOG(maphist,"<- VA below map range",0,0,0,0);
@@ -1831,6 +1836,7 @@ uvm_map_findspace(struct vm_map *map, va
hint, vm_map_min(map), vm_map_max(map), 0);
return (NULL);
}
+ orig_hint = hint;
UVMHIST_LOG(maphist,"<- VA %#jx vs range [%#jx->%#jx]",
hint, vm_map_min(map), vm_map_max(map), 0);
