I tracked this down and it turns out to be a page mapping problem with
one of the sound drivers on the system trashing memory. It's a bug,
but a bug in a vendor supplied driver.
Jeff
On 11/18/15, Jeffrey Merkey <jeffmer...@gmail.com> wrote:
> kallsyms_lookup_name is not returning per_cpu symbols when called.
> The symbols show up when you run something with the kallsyms_iter
> struct but not through the regular interface. I have looked through
> the code and I am not able to determine with certainty if its designed
> this way or just busted. Any help with this would be appreciated.
>
> The following code does display the per_cpu symbols, they just don't
> seem to show up when called from kallsyms_lookup_name.
>
>
> struct kallsym_iter mdb_iter;
> int mdb_kallsyms(char *str, int (*print)(char *s, ...))
> {
> register loff_t pos = 0;
> register struct kallsym_iter *iter = &mdb_iter;
>
> if (!print)
> return 0;
>
> // set to beginning of the kallsyms list
> reset_iter(iter, 0);
> while (1)
> {
> // search the kallsyms list
> if (!update_iter(iter, pos++))
> break;
>
> if (!iter->name[0])
> continue;
>
> // if an exclusion search was specified, skip non-matching entries
> if (str && *str && !strstr(iter->name, str))
> continue;
>
> if (iter->module_name[0])
> {
> if (print("%0*lx %c %s [%s]\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name,
> iter->module_name))
> return 1;
> }
> else
> {
> if (print("%0*lx %c %s\n", (int)(2*sizeof(void*)),
> iter->value, iter->type, iter->name))
> return 1;
> }
> }
> return 0;
> }
> EXPORT_SYMBOL_GPL(mdb_kallsyms);
>
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