Re: [kbuild-all] mm/slub.o:undefined reference to `_GLOBAL_OFFSET_TABLE_'

[Fengguang Wu]

Hi Jesper,

On Thu, Sep 22, 2016 at 10:29:46AM +0200, Jesper Dangaard Brouer wrote:
> On Thu, 22 Sep 2016 13:50:21 +0800
> kbuild test robot <fengguang.wu@xxxxxxxxx> wrote:
>
> > Hi Jesper,
> >
> > FYI, the error/warning still remains.
> >
> > tree:   https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git master
> > head:   7d1e042314619115153a0f6f06e4552c09a50e13
> > commit: d0ecd894e3d5f768a84403b34019c4a7daa05882 slub: optimize bulk slowpath free by detached freelist
> > date:   10 months ago
> > config: microblaze-allnoconfig (attached as .config)
> > compiler: microblaze-linux-gcc (GCC) 6.2.0
> > reproduce:
> >         wget https://git.kernel.org/cgit/linux/kernel/git/wfg/lkp-tests.git/plain/sbin/make.cross -O ~/bin/make.cross
> >         chmod +x ~/bin/make.cross
> >         git checkout d0ecd894e3d5f768a84403b34019c4a7daa05882
> >         # save the attached .config to linux build tree
> >         make.cross ARCH=microblaze
> >
> > All errors (new ones prefixed by >>):
> >
> >    mm/built-in.o: In function `__slab_free.isra.14':
> > >> mm/slub.o:(.text+0x28d1c): undefined reference to `_GLOBAL_OFFSET_TABLE_'
> >    scripts/link-vmlinux.sh: line 52: 18051 Segmentation fault      ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
>
> Hi Fengguang,
>
> I don't really understand if this is a real bug that I need to fix?
>
> It looks like a linker problem, resulting in a "Segmentation fault" for your script...
>
> The mentioned commit: d0ecd894e3d5f768a84 removes a call point to
> __slab_free() and instead call slab_free().  It does not make sense to
> my, why this results in a linker error on this ARCH=microblaze.

Yes this looks strange. CC Michal since such errors only show up in
microblaze:

linus/master errors
âââ microblaze-allnoconfig
â âââ mm-slub.o:(.text):undefined-reference-to-_GLOBAL_OFFSET_TABLE_
âââ microblaze-mmu_defconfig
â âââ net-sunrpc-stats.c:undefined-reference-to-_GLOBAL_OFFSET_TABLE_
âââ microblaze-nommu_defconfig
â âââ net-sunrpc-stats.c:undefined-reference-to-_GLOBAL_OFFSET_TABLE_


I can reproduce the error in commit d0ecd894e3d5f768a84, and
confirmed that it's parent commit builds fine.

=============== commit 461a5e510 ===============
/home/wfg/linux
HEAD is now at 461a5e5... do_div(): generic optimization for constant divisor on 32-bit machines
/home/wfg/linux/obj-compiletest

make ARCH=microblaze

!!! BUILD ERROR !!!
cat /tmp/build-err-461a5e51060c93f5844113f4be9dba513cc92830-wfg
<stdin>:1298:2: warning: #warning syscall userfaultfd not implemented [-Wcpp]
<stdin>:1301:2: warning: #warning syscall membarrier not implemented [-Wcpp]
<stdin>:1304:2: warning: #warning syscall mlock2 not implemented [-Wcpp]
<stdin>:1298:2: warning: #warning syscall userfaultfd not implemented [-Wcpp]
<stdin>:1301:2: warning: #warning syscall membarrier not implemented [-Wcpp]
<stdin>:1304:2: warning: #warning syscall mlock2 not implemented [-Wcpp]
../net/core/rtnetlink.c:1361:32: warning: 'ifla_vf_stats_policy' defined but not used [-Wunused-const-variable=]
static const struct nla_policy ifla_vf_stats_policy[IFLA_VF_STATS_MAX + 1] = {
                               ^~~~~~~~~~~~~~~~~~~~
../net/core/net-sysfs.c:32:19: warning: 'fmt_long_hex' defined but not used [-Wunused-const-variable=]
static const char fmt_long_hex[] = "%#lx\n";
                  ^~~~~~~~~~~~
../fs/proc/base.c:2239:37: warning: 'proc_timers_operations' defined but not used [-Wunused-const-variable=]
static const struct file_operations proc_timers_operations = {
                                    ^~~~~~~~~~~~~~~~~~~~~~
../fs/cifs/netmisc.c:133:40: warning: 'mapping_table_ERRHRD' defined but not used [-Wunused-const-variable=]
static const struct smb_to_posix_error mapping_table_ERRHRD[] = {
                                       ^~~~~~~~~~~~~~~~~~~~
../net/ipv4/ping.c:1139:36: warning: 'ping_v4_seq_ops' defined but not used [-Wunused-const-variable=]
static const struct seq_operations ping_v4_seq_ops = {
                                   ^~~~~~~~~~~~~~~
net/built-in.o: In function `rpc_print_iostats':
/home/wfg/linux/obj-compiletest/../net/sunrpc/stats.c:204: undefined reference to `_GLOBAL_OFFSET_TABLE_'
../scripts/link-vmlinux.sh: line 52: 98396 Segmentation fault      ${LD} ${LDFLAGS} ${LDFLAGS_vmlinux} -o ${2} -T ${lds} ${KBUILD_VMLINUX_INIT} --start-group ${KBUILD_VMLINUX_MAIN} --end-group ${1}
make[1]: *** [vmlinux] Error 139
make[1]: Target '_all' not remade because of errors.
make: *** [sub-make] Error 2


Thanks,
Fengguang