Re: [BUG] fatal hang untarring 90GB file, possibly writeback related.

James Bottomley
2011-04-29T15:37:24Z

On Fri, 2011-04-29 at 12:23 +0200, Sedat Dilek wrote:
> But as I see these RCU (CPU) stalls, the patch from [1] might be worth a try.
> First, I have seen negative effects on my UP-system was when playing
> with linux-next [2].
> It was not clear what the origin was and the the side-effects were
> somehow "bizarre".
> The issue could be easily reproduced by tar-ing the kernel build-dir
> to an external USB-hdd.
> The issue kept RCU and TIP folks really busy.
> Before stepping 4 weeks in the dark, give it a try and let me know in
> case of success.

Well, it's highly unlikely because that's a 2.6.39 artifact and the bug
showed up in 2.6.38 ... I tried it just in case with no effect, so we
know it isn't the cause.

> For the systemd/cgroups part of the discussion (yes, I followed this
> thread in parallel):
> The patch from [4] might be interesting (untested here).

What makes you think that? This patch is about rcu problems in cgroup
manipulation through the mounted cgroup control filesystems. The bug in
question manifests when all of that is quiescent, so it's not likely to
be related.

James