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Index: sys/kern/subr_vmem.c
===================================================================
--- sys/kern/subr_vmem.c
+++ sys/kern/subr_vmem.c
@@ -249,6 +249,18 @@
vmem_t *memguard_arena = &memguard_arena_storage;
#endif
+static bool
+bt_isbusy(bt_t *bt)
+{
+ return (bt->bt_type == BT_TYPE_BUSY);
+}
+
+static bool
+bt_isfree(bt_t *bt)
+{
+ return (bt->bt_type == BT_TYPE_FREE);
+}
+
/*
* Fill the vmem's boundary tag cache. We guarantee that boundary tag
* allocation will not fail once bt_fill() passes. To do so we cache
@@ -791,24 +803,48 @@
static void
vmem_add1(vmem_t *vm, vmem_addr_t addr, vmem_size_t size, int type)
{
- bt_t *btspan;
- bt_t *btfree;
+ bt_t *btfree, *btprev, *btspan;
+ VMEM_ASSERT_LOCKED(vm);
MPASS(type == BT_TYPE_SPAN || type == BT_TYPE_SPAN_STATIC);
MPASS((size & vm->vm_quantum_mask) == 0);
- btspan = bt_alloc(vm);
- btspan->bt_type = type;
- btspan->bt_start = addr;
- btspan->bt_size = size;
- bt_insseg_tail(vm, btspan);
+ if (vm->vm_releasefn == NULL) {
+ /*
+ * The new segment will never be released, so see if it is
+ * contiguous with respect to an existing segment. In this case
+ * a span tag is not needed, and it may be possible now or in
+ * the future to coalesce the new segment with an existing free
+ * segment.
+ */
+ btprev = TAILQ_LAST(&vm->vm_seglist, vmem_seglist);
+ if ((!bt_isbusy(btprev) && !bt_isfree(btprev)) ||
+ btprev->bt_start + btprev->bt_size != addr)
+ btprev = NULL;
+ } else {
+ btprev = NULL;
+ }
- btfree = bt_alloc(vm);
- btfree->bt_type = BT_TYPE_FREE;
- btfree->bt_start = addr;
- btfree->bt_size = size;
- bt_insseg(vm, btfree, btspan);
- bt_insfree(vm, btfree);
+ if (btprev == NULL || bt_isbusy(btprev)) {
+ if (btprev == NULL) {
+ btspan = bt_alloc(vm);
+ btspan->bt_type = type;
+ btspan->bt_start = addr;
+ btspan->bt_size = size;
+ bt_insseg_tail(vm, btspan);
+ }
+
+ btfree = bt_alloc(vm);
+ btfree->bt_type = BT_TYPE_FREE;
+ btfree->bt_start = addr;
+ btfree->bt_size = size;
+ bt_insseg_tail(vm, btfree);
+ bt_insfree(vm, btfree);
+ } else {
+ bt_remfree(vm, btprev);
+ btprev->bt_size += size;
+ bt_insfree(vm, btprev);
+ }
vm->vm_size += size;
}
@@ -1143,6 +1179,7 @@
{
VMEM_LOCK(vm);
+ KASSERT(vm->vm_size == 0, ("%s: arena is non-empty", __func__));
vm->vm_importfn = importfn;
vm->vm_releasefn = releasefn;
vm->vm_arg = arg;
@@ -1395,8 +1432,8 @@
}
out:
VMEM_UNLOCK(vm);
- if (error != 0 && (flags & M_NOWAIT) == 0)
- panic("failed to allocate waiting allocation\n");
+ KASSERT(error == 0 || (flags & M_NOWAIT) != 0,
+ ("%s: M_WAITOK allocation failed", __func__));
return (error);
}

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