Re: crash failure with 2.6.36-rc3 vmcore

[Guenter Roeck]

On Sat, Sep 04, 2010 at 11:07:43AM -0400, caiqian@xxxxxxxxxx wrote:
> Sorry for the confusion. Here is some background. The test here was to use the crash utility to analyse a vmcore generated from kdump. This commit caused its subcommand mod -S failed to gather the module section data from the in-kernel data structure as it looks like it still depends on this field. I am not sure if that the crash utility just need to be adjusted to cope with this kernel change.
> 
That would be the proper fix.

Question is what version of the crash utility you are using.
The one included in my distribution (reporting to be version 4.1.0)
doesn't include the code below.

Thanks,
Guenter

> From http://people.redhat.com/anderson/crash_sources/symbols.c
> /*
>  *  Gather the module section data from the in-kernel data structures.
>  */
> static int
> add_symbol_file_kallsyms(struct load_module *lm, struct gnu_request *req)
> {
>         int len, buflen, done, nsections, retval;
>         ulong vaddr, array_entry, attribute, owner, name, address;
>         long name_type;
>         char buf[BUFSIZE];
>         char section_name[BUFSIZE];
>         ulong section_vaddr;
> 
>         if (!(st->flags & (MODSECT_V1|MODSECT_V2|MODSECT_V3|MODSECT_UNKNOWN))) {
>                 STRUCT_SIZE_INIT(module_sect_attr, "module_sect_attr");
>                 MEMBER_OFFSET_INIT(module_sect_attrs,
>                         "module", "sect_attrs");
>                 MEMBER_OFFSET_INIT(module_sect_attrs_attrs,
>                         "module_sect_attrs", "attrs");
>                 MEMBER_OFFSET_INIT(module_sect_attrs_nsections,
>                         "module_sect_attrs", "nsections");
>                 MEMBER_OFFSET_INIT(module_sect_attr_mattr,
>                         "module_sect_attr", "mattr");
>                 MEMBER_OFFSET_INIT(module_sect_attr_name,
>                         "module_sect_attr", "name");
>                 MEMBER_OFFSET_INIT(module_sect_attr_address,
>                         "module_sect_attr", "address");
>                 MEMBER_OFFSET_INIT(module_attribute_attr,
>                         "module_attribute", "attr");
>                 MEMBER_OFFSET_INIT(module_sect_attr_attr,
>                         "module_sect_attr", "attr");
>                 MEMBER_OFFSET_INIT(module_sections_attrs,
>                         "module_sections", "attrs");
>                 MEMBER_OFFSET_INIT(attribute_owner,
>                         "attribute", "owner");
> ...
>                 owner = attribute + OFFSET(attribute_owner);
> 
> 
> ----- "Guenter Roeck" <guenter.roeck@xxxxxxxxxxxx> wrote:
> 
> > Hi,
> > 
> > On Sat, Sep 04, 2010 at 02:01:06AM -0400, CAI Qian wrote:
> > > 
> > > > crash> mod -S
> > > > 
> > > > mod: invalid structure member offset: attribute_owner
> > > >      FILE: symbols.c  LINE: 8577  FUNCTION:
> > add_symbol_file_kallsyms()
> > > > 
> > > >      MODULE       NAME                   SIZE  OBJECT FILE
> > > > ffffffffa000de60  dm_mod                76230 
> > > >
> > /lib/modules/2.6.36-rc2-mm1-wqfix-mkdfix+/kernel/drivers/md/dm-mod.ko
> > > > [/usr/bin/crash] error trace: 4affb0 => 4f3236 => 4f12b5 =>
> > 4e587a
> > > > 
> > > >   4e587a: OFFSET_verify.clone.4+186
> > > >   4f12b5: add_symbol_file+933
> > > >   4f3236: load_module_symbols+566
> > > >   4affb0: do_module_cmd+1264
> > > > 
> > > > mod: invalid structure member offset: attribute_owner
> > > >      FILE: symbols.c  LINE: 8577  FUNCTION:
> > add_symbol_file_kallsyms()
> > 
> > What do I have to do to reproduce this crash ? 
> > 
> > Was the module in question compiled w/ the kernel, or separately ?
> > Did it use the correct kernel header files for compilation ?
> > Was the kernel version -rc3, or some other patched version ?
> > 
> > Just wondering, since the above message says
> > 2.6.36-rc2-mm1-wqfix-mkdfix+,
> > which seems to indicate that it included some modifications.
> > 
> > Thanks,
> > Guenter
> > 
> > > This failure was due to this commit,
> > > 
> > > commit 6fd69dc578fa0b1bbc3aad70ae3af9a137211707
> > > Author: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> > > Date:   Wed Jul 28 22:09:26 2010 -0700
> > > 
> > >     sysfs: Remove owner field from sysfs struct attribute
> > >     
> > >     Signed-off-by: Guenter Roeck <guenter.roeck@xxxxxxxxxxxx>
> > >     Acked-by: Tejun Heo <tj@xxxxxxxxxx>
> > >     Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxx>
> > > 
> > > diff --git a/include/linux/sysfs.h b/include/linux/sysfs.h
> > > index 8bf06b6..3c92121 100644
> > > --- a/include/linux/sysfs.h
> > > +++ b/include/linux/sysfs.h
> > > @@ -22,14 +22,8 @@ struct kobject;
> > >  struct module;
> > >  enum kobj_ns_type;
> > >  
> > > -/* FIXME
> > > - * The *owner field is no longer used.
> > > - * x86 tree has been cleaned up. The owner
> > > - * attribute is still left for other arches.
> > > - */
> > >  struct attribute {
> > >         const char              *name;
> > > -       struct module           *owner;
> > >         mode_t                  mode;
> > >  #ifdef CONFIG_DEBUG_LOCK_ALLOC
> > >         struct lock_class_key   *key;
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