Author: alc
Date: Thu May 24 04:33:32 2012
New Revision: 235882
URL: http://svn.freebsd.org/changeset/base/235882
Log:
MFC r232288
Simplify kmem_alloc() by eliminating code that existed on account of
external pagers in Mach.
Modified:
stable/9/sys/vm/vm_kern.c
Directory Properties:
stable/9/sys/ (props changed)
Modified: stable/9/sys/vm/vm_kern.c
==============================================================================
--- stable/9/sys/vm/vm_kern.c Thu May 24 04:24:17 2012 (r235881)
+++ stable/9/sys/vm/vm_kern.c Thu May 24 04:33:32 2012 (r235882)
@@ -161,7 +161,6 @@ kmem_alloc(map, size)
{
vm_offset_t addr;
vm_offset_t offset;
- vm_offset_t i;
size = round_page(size);
@@ -187,35 +186,6 @@ kmem_alloc(map, size)
vm_map_unlock(map);
/*
- * Guarantee that there are pages already in this object before
- * calling vm_map_wire. This is to prevent the following
- * scenario:
- *
- * 1) Threads have swapped out, so that there is a pager for the
- * kernel_object. 2) The kmsg zone is empty, and so we are
- * kmem_allocing a new page for it. 3) vm_map_wire calls vm_fault;
- * there is no page, but there is a pager, so we call
- * pager_data_request. But the kmsg zone is empty, so we must
- * kmem_alloc. 4) goto 1 5) Even if the kmsg zone is not empty: when
- * we get the data back from the pager, it will be (very stale)
- * non-zero data. kmem_alloc is defined to return zero-filled memory.
- *
- * We're intentionally not activating the pages we allocate to prevent a
- * race with page-out. vm_map_wire will wire the pages.
- */
- VM_OBJECT_LOCK(kernel_object);
- for (i = 0; i < size; i += PAGE_SIZE) {
- vm_page_t mem;
-
- mem = vm_page_grab(kernel_object, OFF_TO_IDX(offset + i),
- VM_ALLOC_NOBUSY | VM_ALLOC_ZERO | VM_ALLOC_RETRY);
- mem->valid = VM_PAGE_BITS_ALL;
- KASSERT((mem->oflags & VPO_UNMANAGED) != 0,
- ("kmem_alloc: page %p is managed", mem));
- }
- VM_OBJECT_UNLOCK(kernel_object);
-
- /*
* And finally, mark the data as non-pageable.
*/
(void) vm_map_wire(map, addr, addr + size,
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