[Drbd-dev] drbd 8.4.3: refcounter overflow on re-sync

[Lars Ellenberg]

On Fri, Sep 19, 2014 at 05:16:53PM +0200, Marc Schiffbauer wrote:
> * Lars Ellenberg schrieb am 19.09.14 um 16:48 Uhr:
> >On Fri, Sep 19, 2014 at 11:49:09AM +0200, Marc Schiffbauer wrote:
> >>Hi,
> >>
> >
> >If you resolve that to a code line,
> >I may be able to figure out what PAX is talking about.
> >
> >But from this stack trace alone, I have absolutely no idea what PAX
> >is trying to say, which refcount could possibly be meant there,
> >let alone why it could possibly overflow or.
> >
> >Ah, ok. Looking at [1], "PaX Team" says:
> >.---
> >| after having looked at the drbd code a bit i think this could be a
> >| real bug in drbd but only upstream can tell for sure so you'll have to
> >| contact them. you can show them the following that i figured out so far:
> >|
> >| the refcount overflow was detected in
> >| drivers/block/drbd/drbd_bitmap.c:bm_page_io_async at the
> >|
> >| atomic_add(len >> 9, &mdev->rs_sect_ev)
> >
> >Well, yes, why would it not overflow.
> >It is *not* a refcount.
> >It is an atomic counter.
> >It is meant to overflow.
> 
> Ok, then I can report this back and it should be fixed in PaX as a
> false postive. Thanks for clarifying this.

I still don't get why PAX is even sending a signal there.
How could sending a signal possibly help against an overflowing counter?

Ah well. I don't need to get everything ...

Thanks,

	Lars