Re: 2.6.0-test7-mm1

[Ben Collins <bcollins@debian.org>]

On Wed, Oct 15, 2003 at 10:28:10AM -0700, Andrew Morton wrote:
> Bradley Chapman <kakadu_croc@yahoo.com> wrote:
> >
> > You're welcome. Unfortunately I got this non-fatal Oops when I first booted:
> > 
> >  ohci1394: $Rev: 1045 $ Ben Collins <bcollins@debian.org>
> >  ohci1394_0: OHCI-1394 1.1 (PCI): IRQ=[10]  MMIO=[e8207000-e82077ff]  Max
> >  Packet=[2048]
> >  Debug: sleeping function called from invalid context at mm/slab.c:1869
> >  in_atomic():1, irqs_disabled():0
> >  Call Trace:
> >   [<c0123fc6>] __might_sleep+0xa0/0xc2
> >   [<c0156bc4>] __kmalloc+0x204/0x216
> >   [<e08a9ed4>] hpsb_create_hostinfo+0x6b/0xe8 [ieee1394]
> >   [<e08af0e6>] nodemgr_add_host+0x23/0x1d2 [ieee1394]
> >   [<c0216bd4>] sprintf+0x1f/0x23
> >   [<e08aa789>] highlevel_add_host+0x6b/0x6f [ieee1394]
> >   [<e08a9cce>] hpsb_add_host+0x6d/0x95 [ieee1394]
> 
> highlevel_add_host() does read_lock() and then proceeds to do things like
> starting kernel threads under that lock.  The locking is pretty broken
> in there :(

No, highlevel_add_host() itself doesn't start any threads. But it does
pass around data that needs to be locked from changes, and one of the
handlers happens to start a thread, and other things allocate memory
(such as this case).

It's ugly, and I've been trying to clean it up. This case can be fixed
quickly with a simple check in hpsb_create_hostinfo() to pass GFP_ATOMIC
to kmalloc.

My problem right now, is I don't use any architectures that support
preempt, so I don't see a lot of these problems, like I catch with
CONFIG_SMP.

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