Am Freitag, den 03.10.2014, 10:17 +0200 schrieb Richard Weinberger:
> On Fri, Oct 3, 2014 at 1:21 AM, Thomas Meyer <tho...@m3y3r.de> wrote:
> > Hi,
> >
> > When you pass an initrd to UML and the size of the initrd is too big for
> > the current kernel memory, a panic() call is done with the message("Out
> > of memory").
> >
> > But this message never hits the stdout as the following stack trace
> > dumps because there is no current_thread_info() in the UML stack, which
> > is still active at this time:
>
> Do you see the message if you boot UML with the earlyprintk parameter?
No it doesn't. The UML kernel crashes will trying to print the stack
trace.
I tried this drop in arch/um/kernel/dump_stack.c:
#include <linux/kernel.h>
#include <linux/export.h>
#include <linux/sched.h>
#include <linux/smp.h>
#include <linux/atomic.h>
#include <kern_util.h>
void dump_stack(void)
{
struct thread_info* ti = current_thread_info();
if(is_kernel_addr(ti)) {
dump_stack_print_info(KERN_DEFAULT);
show_stack(NULL, NULL);
} else {
printk(KERN_CRIT "Dump_stack from non-kernel stack!\n");
}
}
EXPORT_SYMBOL(dump_stack);
But this doesn't help as UML will crash then in kernel/panic.c while
trying to call atomic_notifier_call_chain(&panic_notifier_list, 0, buf);
I think the root cause is that current_thread_info() returns an invalid
thread_info. The proper fix would be to also have the UML stack an valid
thread_info at the begin of the stack, pointing to init_thread_info.
but don't know how to do this.
what do you think about this?
with kind regards
thomas
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