Re: + kmod-avoid-deadlock-by-recursive-kmod-call.patch added to -mm tree

From: Rusty Russell
Date: Sun Jan 29 2012 - 06:39:20 EST


On Fri, 27 Jan 2012 15:32:34 +0100, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> On 01/27, Rusty Russell wrote:
> > On Thu, 26 Jan 2012 18:56:12 +0100, Oleg Nesterov <oleg@xxxxxxxxxx> wrote:
> > > Can't we simply kill khelper_wq and use system_unbound_wq instead?
> >
> > I'd prefer that, because then we'd hit the existing "too many modprobes"
> > check.
>
> Hmm. Why? I mean, why do you think that s/khelper_wq/system_unbound_wq/
> leads to recursive __request_module's ?
>
> Note that that this patch (which adds kmod_thread_locker) can not limit
> the recursive modprobe loop.
>
>
> OK, yes, with system_unbound_wq we can hit this warning if we have
> max_modprobes UMH_WAIT_EXEC's resulting in __request_module at the
> same time, but probably this is good?

Yes, that's what I'm saying.

We already have a check against too many modprobes, it might be best to
use it.

Cheers,
Rusty.
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