On Wed, 2005-05-25 at 20:48 -0700, Andrew Morton wrote:
> > > --- a/kernel/printk.c 2005-04-12 10:12:19.000000000 +0800
> > > +++ b/kernel/printk.c 2005-04-13 17:22:40.912897328 +0800
> > > @@ -624,8 +624,7 @@ asmlinkage int vprintk(const char *fmt,
> > > log_level_unknown = 1;
> > > }
> > >
> > > - if (!cpu_online(smp_processor_id()) &&
> > > - system_state != SYSTEM_RUNNING) {
> > > + if (!cpu_online(smp_processor_id())) {
> > > /*
> > > * Some console drivers may assume that per-cpu resources have
> > > * been allocated. So don't allow them to be called by this
> > Andrew,
> > Could above patch be put into mm tree?
>
> Well not in that form. I'd appreciate being sent patches which are
> applyable rather than mangled messes, please.
>
> > It fixes the oops of CPU hotplug
> > with radeon fb enabled.
> > The reason is the per-cpu data (radeon fb calls kmalloc) isn't
> > initialized when CPU hotplug is processing. system_state is
> > SYSTEM_RUNNING for cpu hotplug.
>
> That system_state test was explicitly added by davidm a year ago:
>
> "- Allow printk on down cpus once system is running."
>
> Please confirm that we in fact do not want to allow downed CPUs to
> print things, then send a patch.
Yep. In the cpu hotplug case, per-cpu data possibly isn't initialized
even the system state is 'running'. As the comments say in the original
code, some console drivers assume per-cpu resources have been allocated.
radeon fb is one such driver, which uses kmalloc. After a CPU is down,
the per-cpu data of slab is freed, so the system crashed when printing
some info.
Thanks,
Shaohua
---
linux-2.6.11-rc5-mm1-root/kernel/printk.c | 3 +--
1 files changed, 1 insertion(+), 2 deletions(-)
diff -puN kernel/printk.c~printk kernel/printk.c
--- linux-2.6.11-rc5-mm1/kernel/printk.c~printk 2005-05-26 13:11:47.333540352 +0800
+++ linux-2.6.11-rc5-mm1-root/kernel/printk.c 2005-05-26 13:11:47.336539896 +0800
@@ -588,8 +588,7 @@ asmlinkage int vprintk(const char *fmt,
log_level_unknown = 1;
}
- if (!cpu_online(smp_processor_id()) &&
- system_state != SYSTEM_RUNNING) {
+ if (!cpu_online(smp_processor_id())) {
/*
* Some console drivers may assume that per-cpu resources have
* been allocated. So don't allow them to be called by this
_
-
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