Author: kib
Date: Wed Nov 20 09:03:48 2013
New Revision: 258367
URL: http://svnweb.freebsd.org/changeset/base/258367
Log:
Vm map code performs clipping when map entry covers region which is
larger than the operational region. If the op region size is zero,
clipping would create a zero-sized map entry. The result is that vm
map splay starts behaving inconsistently, sometimes returning
zero-sized entry, sometimes the next (or previous) entry.
One step further, it could result in e.g. vm_map_wire() setting
MAP_ENTRY_IN_TRANSITION on the zero-sized entry, but failing to clear
it in the done part. The vm_map_delete() than hangs forever waiting
for the flag removal.
Verify for zero-length requests and act as if it is always successfull
without performing any action on the address space.
Diagnosed by: pho
Tested by: pho (previous version)
Reviewed by: alc (previous version)
Sponsored by: The FreeBSD Foundation
MFC after: 1 week
Modified:
head/sys/vm/vm_map.c
Modified: head/sys/vm/vm_map.c
==============================================================================
--- head/sys/vm/vm_map.c Wed Nov 20 08:47:54 2013 (r258366)
+++ head/sys/vm/vm_map.c Wed Nov 20 09:03:48 2013 (r258367)
@@ -1876,6 +1876,9 @@ vm_map_protect(vm_map_t map, vm_offset_t
struct ucred *cred;
vm_prot_t old_prot;
+ if (start == end)
+ return (KERN_SUCCESS);
+
vm_map_lock(map);
VM_MAP_RANGE_CHECK(map, start, end);
@@ -2030,12 +2033,16 @@ vm_map_madvise(
case MADV_AUTOSYNC:
case MADV_NOCORE:
case MADV_CORE:
+ if (start == end)
+ return (KERN_SUCCESS);
modify_map = 1;
vm_map_lock(map);
break;
case MADV_WILLNEED:
case MADV_DONTNEED:
case MADV_FREE:
+ if (start == end)
+ return (KERN_SUCCESS);
vm_map_lock_read(map);
break;
default:
@@ -2190,6 +2197,8 @@ vm_map_inherit(vm_map_t map, vm_offset_t
default:
return (KERN_INVALID_ARGUMENT);
}
+ if (start == end)
+ return (KERN_SUCCESS);
vm_map_lock(map);
VM_MAP_RANGE_CHECK(map, start, end);
if (vm_map_lookup_entry(map, start, &temp_entry)) {
@@ -2222,6 +2231,8 @@ vm_map_unwire(vm_map_t map, vm_offset_t
int rv;
boolean_t need_wakeup, result, user_unwire;
+ if (start == end)
+ return (KERN_SUCCESS);
user_unwire = (flags & VM_MAP_WIRE_USER) ? TRUE : FALSE;
vm_map_lock(map);
VM_MAP_RANGE_CHECK(map, start, end);
@@ -2392,6 +2403,8 @@ vm_map_wire(vm_map_t map, vm_offset_t st
boolean_t fictitious, need_wakeup, result, user_wire;
vm_prot_t prot;
+ if (start == end)
+ return (KERN_SUCCESS);
prot = 0;
if (flags & VM_MAP_WIRE_WRITE)
prot |= VM_PROT_WRITE;
@@ -2833,6 +2846,8 @@ vm_map_delete(vm_map_t map, vm_offset_t
vm_map_entry_t first_entry;
VM_MAP_ASSERT_LOCKED(map);
+ if (start == end)
+ return (KERN_SUCCESS);
/*
* Find the start of the region, and clip it
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