On Fri, Jan 25, 2008 at 11:24:55PM -0800, Greg KH wrote:
> On Fri, Jan 25, 2008 at 11:08:53PM -0800, Yinghai Lu wrote:
> > On Jan 25, 2008 10:14 PM, Greg KH <[EMAIL PROTECTED]> wrote:
> > >
> > > On Fri, Jan 25, 2008 at 10:04:19PM -0800, Yinghai Lu wrote:
> > > > On Jan 25, 2008 2:50 PM, Greg KH <[EMAIL PROTECTED]> wrote:
> > > > > On Fri, Jan 25, 2008 at 02:47:11PM -0800, Greg KH wrote:
> > > > > > On Fri, Jan 25, 2008 at 11:35:56PM +0100, Ingo Molnar wrote:
> > > > > > >
> > > > > > > * Greg KH <[EMAIL PROTECTED]> wrote:
> > > > > > >
> > > > > > > > On Fri, Jan 25, 2008 at 01:05:40PM -0800, Yinghai Lu wrote:
> > > > > > > > > current linus tree + x86.git
> > > > > > > > >
> > > > > > > > > got
> > > > > > > > >
> > > > > > > > > Calling initcall 0xffffffff80b93d98:
> > > > > > > > > threshold_init_device+0x0/0x3f()
> > > > > > > > > BUG: unable to handle kernel NULL pointer dereference at
> > > > > > > > > 0000000000000040
> > > > > > > > > IP: [<ffffffff80458e20>] kobject_uevent_env+0x2a/0x3d9
> > > > > > > >
> > > > > > > > Does this happen on just Linus's tree?
> > > > > > > >
> > > > > > > > Can you send me a .config file for this?
> > > > > > > >
> > > > > > > > What is threshold_init()? Is it something new in the x86.git
> > > > > > > > tree?
> > > > > > >
> > > > > > > no. A quick grep shows that it is in a file that _your_ changes in
> > > > > > > Linus' latest have touched:
> > > > > > >
> > > > > > > arch/x86/kernel/cpu/mcheck/mce_amd_64.c
> > > > > >
> > > > > > Ok, those are pretty much just search/and/replace type changes, but
> > > > > > I
> > > > > > have been running x86-64 boxes with these changes in place.
> > > > >
> > > > > Oh wait, I do see a change. We are now (finally) emitting a kobject
> > > > > uevent for these devices, which somehow the code can't handle
> > > > > properly.
> > > > >
> > > > > Let me go poke this some more, unfortunatly I don't have any AMD 64
> > > > > boxes here anymore, only Intel based processors, so I can't run this
> > > > > module...
> > > >
> > > > it only happens with AMD Quad Core CPU or Fam 10h.
> > > >
> > > > works well with AMD opteron Rev E, and Rev F.
> > >
> > > So this only dies on a multi-core system? Or does 2 processor boxes
> > > work, but not 4?
> >
> > 2 sockets x quad core will fail (fam 10h)
> > 2 sockets x dual core works....( rev E, and rev F opteron)
> >
> > there are some changs between opteron and fam10h. fam10h may have
> > more local vectors for MCE...
> > or more banks and blocks...
> >
> > will look at AMD64 Bios and kernel porting guide for Fam 10h again..
> >
> > wonder if your code uncover some bugs ...
>
> No, the logic in this function is just crazy. It's recursive, but we
> can circumvent the creation for the kobject and whole creation of the
> threshold_block if some conditions are met. That's why we see the
> allocate_threshold_blocks so many times in the callstack, yet only a few
> kobjects created.
>
> Then we blow up in kobject_uevent_env() on the first debug printk.
> Which means that we are just passing in garbage.
>
> Let me know if the patch below fixes this for you, I think it should, as
> there is a code path where b is NULL and then we call kobject_uevent.
>
> Man, this is one time that comments in code would have been very nice to
> have, and why forward goto's into major code blocks are just evil...
>
> thanks,
>
> greg k-h
>
> diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
> b/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
> index 7535887..8a7f204 100644
> --- a/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
> +++ b/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
> @@ -450,7 +450,8 @@ recurse:
> if (err)
> goto out_free;
>
> - kobject_uevent(&b->kobj, KOBJ_ADD);
> + if (b && &b->kobj)
> + kobject_uevent(&b->kobj, KOBJ_ADD);
>
> return err;
>
Actually the second test doesn't make sense, it can just be:
diff --git a/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
b/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
index 7535887..8a7f204 100644
--- a/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
+++ b/arch/x86/kernel/cpu/mcheck/mce_amd_64.c
@@ -450,7 +450,8 @@ recurse:
if (err)
goto out_free;
- kobject_uevent(&b->kobj, KOBJ_ADD);
+ if (b)
+ kobject_uevent(&b->kobj, KOBJ_ADD);
return err;
--
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