The kernel-source package contains entries in the include/linux/modules
directory.  This can cause a build of the kernel tree to fail.

Steps to reproduce:

rpm -Uhv kernel-source-2.2.16-22.i386.rpm
cd /usr/src/linux
make oldconfig
make clean && make dep && make bzImage

build will fail with the following error:
gcc -D__KERNEL__ -I/usr/src/linux/include -Wall -Wstrict-prototypes -O2
-fomit-frame-pointer -fno-strict-aliasing -pipe -fno-strength-reduce -m386
-DCPU=386   -DEXPORT_SYMTAB -c ksyms.c
In file included from /usr/src/linux/include/linux/modversions.h:50,
                 from /usr/src/linux/include/linux/module.h:19,
                 from ksyms.c:14:
/usr/src/linux/include/linux/modules/i386_ksyms.ver:6: warning: `cpu_data'
redefined
/usr/src/linux/include/asm/processor.h:96: warning: this is the location of
the previous definition
/usr/src/linux/include/linux/modules/i386_ksyms.ver:28: warning:
`smp_num_cpus' redefined
/usr/src/linux/include/linux/smp.h:77: warning: this is the location of the
previous definition
/usr/src/linux/include/linux/modules/i386_ksyms.ver:118: warning:
`smp_call_function' redefined
/usr/src/linux/include/linux/smp.h:83: warning: this is the location of the
previous definition
In file included from /usr/src/linux/include/linux/interrupt.h:51,
                 from ksyms.c:21:
/usr/src/linux/include/asm/hardirq.h:23: warning: `synchronize_irq'
redefined
/usr/src/linux/include/linux/modules/i386_ksyms.ver:138: warning: this is
the location of the previous definition
In file included from /usr/src/linux/include/linux/interrupt.h:52,
                 from ksyms.c:21:
/usr/src/linux/include/asm/softirq.h:75: warning: `synchronize_bh'
redefined
/usr/src/linux/include/linux/modules/i386_ksyms.ver:142: warning: this is
the location of the previous definition
/usr/src/linux/include/linux/kernel_stat.h: In function `kstat_irqs':
In file included from ksyms.c:17:
/usr/src/linux/include/linux/kernel_stat.h:47: `smp_num_cpus' undeclared
(first use in this function)
/usr/src/linux/include/linux/kernel_stat.h:47: (Each undeclared identifier
is reported only once
/usr/src/linux/include/linux/kernel_stat.h:47: for each function it appears
in.)
make[2]: *** [ksyms.o] Error 1
make[2]: Leaving directory `/usr/src/linux-2.2.16/kernel'
make[1]: *** [first_rule] Error 2
make[1]: Leaving directory `/usr/src/linux-2.2.16/kernel'
make: *** [_dir_kernel] Error 2


-------------------------------------------

Note:  Running 'make mrproper' on the tree does fix this.