Make MemMap::MapAnonymous() fail if the requested address is not available.
Change MapAnonymous() so that a requested address vs. actual map
address mismatch will cause a failure. The existing MapAnonymous()
call sites do not check this. This should prevent potential rare case
bugs where mmap does not happen to map a region at an specified
address.
There's a potential bug that if MapAnonymous() does not guarantee the
requested address (and there's a gap between the image/oat files and
the zygote/malloc space), then GC could in theory allocate a large
object space in the gap. This would break the GC notion of the immune
space. This change will prevent this by causing all non-moving spaces
to be (really) adjacent, with no gaps in between, which CL 87711
missed.
Change-Id: Id4adb0e30adbad497334d7e00def4c0c66b15719
diff --git a/runtime/gc/space/image_space.cc b/runtime/gc/space/image_space.cc
index 5480639..bb52c66 100644
--- a/runtime/gc/space/image_space.cc
+++ b/runtime/gc/space/image_space.cc
@@ -201,7 +201,7 @@
UniquePtr<MemMap> map(MemMap::MapFileAtAddress(image_header.GetImageBegin(),
image_header.GetImageSize(),
PROT_READ | PROT_WRITE,
- MAP_PRIVATE | MAP_FIXED,
+ MAP_PRIVATE,
file->Fd(),
0,
false,