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

[Marc Schiffbauer]

* Lars Ellenberg schrieb am 23.09.14 um 13:03 Uhr:
>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.


Another question PaX-Team is asking:

what about rs_sect_in?


Thanks


-- 
[*] sys4 AG

http://sys4.de, +49 (89) 30 90 46 64
Franziskanerstraße 15, 81669 München

Sitz der Gesellschaft: München, Amtsgericht München: HRB 199263
Vorstand: Patrick Ben Koetter, Marc Schiffbauer
Aufsichtsratsvorsitzender: Florian Kirstein