Re: 2.6.32-rc6 BUG at mm/slab.c:2869!

From: Bob Copeland
Date: Fri Aug 21 2009 - 08:38:55 EST


On Fri, Aug 21, 2009 at 08:46:37AM +0200, Vegard Nossum wrote:
> 2009/8/21 Bob Copeland <me@xxxxxxxxxxxxxxx>:
> > WARNING: kmemcheck: Caught 32-bit read from freed memory (f34a443c)
> > eeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee008a06f700011000
> > a a a a a a a a a a a a a a a a a a a a a a a a f f f f f f f f
> >
> > I think that is list_empty() here where %eax is list_head
> > and event_list->next is the read location... which definitely
> > doesn't look like a pointer, if I'm reading it correctly.
>
> I think f34a443c is a valid pointer. On my machine, at least:

I meant list->next, which was 00100100 here. (By the way, my first
time using kmemcheck, very nice tool!)

[race condition explanation snipped]

> I think that's it. Any thoughts? I put Eric Paris on Cc.

Thanks! With a fresh pull containing the fsnotify fix the kmemcheck
warning is gone. So unless I see anything else I'll assume that this
one is already fixed, sorry for the false alarm.

--
Bob Copeland %% www.bobcopeland.com

--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/