Description of problem:
As kernel randomizes its small "[vdso]" mapping it sometimes maps it to the
place where glibc is prelinked, needing a regular glibc relocation to a
different place upon its loading.

Version-Release number of selected component (if applicable):
glibc-2.5.90-15.i686
prelink-0.3.10-1.i386
kernel-xen-2.6.19-1.2898.2.3.fc7.i686

How reproducible:
Reliably, in ~20% of cases.

Steps to Reproduce:
1. yum install prelink
2. /etc/cron.daily/prelink
3. LD_DEBUG=statistics cat /proc/self/maps |grep
'00c52000.*/lib/i686/nosegneg/libc-2.5.90.so' # address of the prelinked glibc

Actual results:
[ Only in 20% of cases, in 80% of cases it is as in the "Expected results". ]
$ LD_DEBUG=statistics cat /proc/self/maps |grep
'00c52000.*/lib/i686/nosegneg/libc-2.5.90.so'
     19816:
     19816:     runtime linker statistics:
     19816:       total startup time in dynamic loader: 3138178 clock cycles
     19816:                 time needed for relocation: 460991 clock cycles (14.6%)
     19816:                      number of relocations: 99
     19816:           number of relocations from cache: 5
     19816:             number of relative relocations: 1240
     19816:                time needed to load objects: 1325265 clock cycles (42.2%)

Expected results:
$ LD_DEBUG=statistics cat /proc/self/maps |grep
'00c52000.*/lib/i686/nosegneg/libc-2.5.90.so'
     19811:
     19811:     runtime linker statistics:
     19811:       total startup time in dynamic loader: 1356025 clock cycles
     19811:                 time needed for relocation: 50154 clock cycles (3.6%)
     19811:                      number of relocations: 0
     19811:           number of relocations from cache: 17
     19811:             number of relative relocations: 0
     19811:                time needed to load objects: 625825 clock cycles (46.1%)
00c52000-00da0000 r-xp 00000000 03:05 4186805    /lib/i686/nosegneg/libc-2.5.90.so

Additional info:
linux-2.6.18.i686/mm/mmap.c
#define SHLIB_BASE             0x00110000
arch_get_unmapped_exec_area()
        if (!addr && !(flags & MAP_FIXED))
                addr = randomize_range(SHLIB_BASE, 0x01000000, len);

VDSO mapping should have its mapped range reduced/adjusted in cooperation with
prelink:
prelink/src/arch-i386.c
#define REG0S   0x00101000
#define REG0E   0x00e00000

[ I did not check the non-i686 platforms. ]