Why do asan tests fail on gcc20?

[Jonathan Wakely]

When running the testsuite on gcc20 in the compiler farm I always see FAILs like

FAIL: g++.dg/asan/symbolize-callback-1.C  -O2  output pattern test, is
==17697== ERROR: Failed to allocate 0x20000001000 (2199023259648)
bytes at address 0x0ffffffff000 (12)
==17697== ReserveShadowMemoryRange failed while trying to map
0x20000001000 bytes. Perhaps you're using ulimit -v
, should match MySymbolizer
FAIL: g++.dg/asan/symbolize-callback-1.C  -O2 -flto
-flto-partition=none  output pattern test, is ==18220== ERROR: Failed
to allocate 0x20000001000 (2199023259648) bytes at address
0x0ffffffff000 (12)
==18220== ReserveShadowMemoryRange failed while trying to map
0x20000001000 bytes. Perhaps you're using ulimit -v
, should match MySymbolizer
FAIL: g++.dg/asan/symbolize-callback-1.C  -O2 -flto  output pattern
test, is ==18714== ERROR: Failed to allocate 0x20000001000
(2199023259648) bytes at address 0x0ffffffff000 (12)
==18714== ReserveShadowMemoryRange failed while trying to map
0x20000001000 bytes. Perhaps you're using ulimit -v
, should match MySymbolizer

Is this due to some setting of the box (ulimit -v is unlimited) or am
I doing something wrong or missing some new prerequisite?

Configured trunk with
~/src/gcc/configure --prefix=$HOME/gcc/4.x --with-system-zlib
--with-gnu-ld --with-gnu-as --disable-libitm --disable-libquadmath
--enable-libstdcxx-time --disable-checking --enable-languages=c,c++