Software Environment: gcc 3.4.6, binutils 2.17 Problem Description: Warnings appeared while building kernel: WARNING: arch/i386/kernel/built-in.o(.data+0x2148): Section mismatch: reference to .init.text: (between 'thermal_throttle_cpu_notifier' and 'mtrr_mutex') WARNING: kernel/built-in.o(.text+0x15f84): Section mismatch: reference to .init.text: (between 'kthreadd' and 'init_waitqueue_head')
Created attachment 11886 [details] config
Subject: Re: New: Section mismatch: reference to .init.text On Tue, 26 Jun 2007 10:46:36 -0700 (PDT) bugme-daemon@bugzilla.kernel.org wrote: > http://bugzilla.kernel.org/show_bug.cgi?id=8679 > > Summary: Section mismatch: reference to .init.text > Product: Other > Version: 2.5 > KernelVersion: 2.6.22-rc6 > Platform: All > OS/Version: Linux > Tree: Mainline > Status: NEW > Severity: normal > Priority: P1 > Component: Configuration > AssignedTo: zippel@linux-m68k.org > ReportedBy: wbrana@gmail.com > > > Software Environment: > gcc 3.4.6, binutils 2.17 > > Problem Description: > Warnings appeared while building kernel: > > WARNING: arch/i386/kernel/built-in.o(.data+0x2148): Section mismatch: > reference > to .init.text: (between 'thermal_throttle_cpu_notifier' and 'mtrr_mutex') > WARNING: kernel/built-in.o(.text+0x15f84): Section mismatch: reference to > .init.text: (between 'kthreadd' and 'init_waitqueue_head') I don't see the kernel/built-in.o warning when I build this (I have binutils 2.16++). Can you test the patch below to verify that it fixes the warning? On the other warning ('thermal_throttle_cpu_notifier'), we have: static struct notifier_block thermal_throttle_cpu_notifier = { .notifier_call = thermal_throttle_cpu_callback, }; where CONFIG_CPU_HOTPLUG=n, so __cpuinit == __init in: static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block *nfb, unsigned long action, void *hcpu) so CPU hotplug actions should never happen here. Still, we have a registered notifier that is in __init space and has been discarded... :( Any suggestions out there? --- From: Randy Dunlap <randy.dunlap@oracle.com> kthreadd_setup() is in an __init section, but we know that it's safe to be called from kthreadd() since the latter is only called at kernel init time, so mark kthreadd_setup() __init_refok so that modpost won't complain about what text section it is in. Signed-off-by: Randy Dunlap <randy.dunlap@oracle.com> --- kernel/kthread.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) --- linux-2.6.22-rc6.orig/kernel/kthread.c +++ linux-2.6.22-rc6/kernel/kthread.c @@ -215,7 +215,7 @@ int kthread_stop(struct task_struct *k) EXPORT_SYMBOL(kthread_stop); -static __init void kthreadd_setup(void) +static __init_refok void kthreadd_setup(void) { struct task_struct *tsk = current;
Subject: Re: Section mismatch: reference to .init.text > > On the other warning ('thermal_throttle_cpu_notifier'), we have: > > static struct notifier_block thermal_throttle_cpu_notifier = > { > .notifier_call = thermal_throttle_cpu_callback, > }; > > where CONFIG_CPU_HOTPLUG=n, so __cpuinit == __init in: > > static __cpuinit int thermal_throttle_cpu_callback(struct notifier_block > *nfb, > unsigned long action, > void *hcpu) > > > so CPU hotplug actions should never happen here. Still, we have > a registered notifier that is in __init space and has been discarded... :( > Any suggestions out there? Kill the three uses of __cpuinit in this file. The noise/benefit level does not justofy anything special. We could do: static struct notifier_block __init_refok thermal_throttle_cpu_notifier = and we could accept __init references from variables named *_notifier. But seems to much special casing to my taste. Sam
[ The kthread warning is resolved in latest kernel. ] (In reply to comment #3) > Subject: Re: Section mismatch: reference to .init.text > > > > > On the other warning ('thermal_throttle_cpu_notifier'), we have: > > > > static struct notifier_block thermal_throttle_cpu_notifier = > > { > > .notifier_call = thermal_throttle_cpu_callback, > > }; > > > > where CONFIG_CPU_HOTPLUG=n, so __cpuinit == __init in: > > > > static __cpuinit int thermal_throttle_cpu_callback(...) > > > > so CPU hotplug actions should never happen here. Still, we have > > a registered notifier that is in __init space and has been discarded... :( > > Any suggestions out there? > > Kill the three uses of __cpuinit in this file. > The noise/benefit level does not justofy anything special. > > We could do: > static struct notifier_block __init_refok thermal_throttle_cpu_notifier = > and we could accept __init references from variables named *_notifier.> > > > But seems to much special casing to my taste. Hi Sam, When CONFIG_HOTPLUG_CPU=n, this warning occurs because the thermal_throttle_cpu_notifier notifier_block is in .data but the callback function itself is __cpuinit == .init.text. The warning is bogus, because the callback will never be called out if HOTPLUG_CPU=n in the first place. To shut the warning up, the notifier block itself must be made __cpuinitdata because it has no purpose in life after initcall stage, if HOTPLUG_CPU=n, just like the callback function itself does not have.
Hi wbrana, please try the patch at: http://lkml.org/lkml/2007/8/21/6 and let us know if the thermal_throttle_cpu_notifier section mismatch warning you're seeing goes away, so we can close this bug. Thank you.
I compiled 2.6.22.4 with patch from http://lkml.org/lkml/2007/8/21/6 Hunk #1 succeeded at 150 (offset -2 lines). I can't see thermal_throttle_cpu_notifier section mismatch warning.