On 01/26/2016 07:53 PM, Dave Jones wrote:
> <off-list because of huge config>
>
> On Mon, Jan 25, 2016 at 05:03:48PM +0300, Andrey Ryabinin wrote:
>
> > > So disabling that option fixed booting on one machine, but every other
> I've
> > > tried it on hangs the same way, really early. Any thoughts on how to
> chase this down ?
> > >
> > Try to disable instrumentation for early code, like in the patch bellow.
> >
> >
> > diff --git a/arch/x86/kernel/Makefile b/arch/x86/kernel/Makefile
> > index b1b78ff..d39a954 100644
> > --- a/arch/x86/kernel/Makefile
> > +++ b/arch/x86/kernel/Makefile
> > @@ -20,6 +20,8 @@ KASAN_SANITIZE_head$(BITS).o := n
> > KASAN_SANITIZE_dumpstack.o := n
> > KASAN_SANITIZE_dumpstack_$(BITS).o := n
> >
> > +UBSAN_SANITIZE := n
> > +
> > CFLAGS_irq.o := -I$(src)/../include/asm/trace
> >
> > obj-y := process_$(BITS).o signal.o
>
> This didn't help.
>
> > Also send me you .config please. Perhaps I will be able to reproduce this.
>
> below. Though I diffed a similar config from a machine where UBSAN works,
> and the only differences seemed to be mostly benign stuff or hw specific
> drivers.
>
So after I enabled UBSAN_ALIGNMENT in your config, the kernel didn't boot.
That is because unaligned access happens before lockdep_init() so ubsan
callback takes the
spinlock before locked_init() which is not allowed.
As far as I understood most of your machines doesn't boot even without
UBSAN_ALIGNMENT.
So I'm guessing it might be similar problem.
Could you try it without CONFIG_DEBUG_LOCKDEP?
Or alternatively with patch like this:
diff --git a/lib/ubsan.c b/lib/ubsan.c
index 8799ae5..220e9d9 100644
--- a/lib/ubsan.c
+++ b/lib/ubsan.c
@@ -146,13 +146,13 @@ static bool location_is_valid(struct source_location *loc)
return loc->file_name != NULL;
}
-static DEFINE_SPINLOCK(report_lock);
+//static DEFINE_SPINLOCK(report_lock);
static void ubsan_prologue(struct source_location *location,
unsigned long *flags)
{
current->in_ubsan++;
- spin_lock_irqsave(&report_lock, *flags);
+// spin_lock_irqsave(&report_lock, *flags);
pr_err("========================================"
"========================================\n");
@@ -164,7 +164,7 @@ static void ubsan_epilogue(unsigned long *flags)
dump_stack();
pr_err("========================================"
"========================================\n");
- spin_unlock_irqrestore(&report_lock, *flags);
+// spin_unlock_irqrestore(&report_lock, *flags);
current->in_ubsan--;
}
