Re: ipw2200: firmware DMA loading rework
From: Mel Gorman
Date: Tue Sep 08 2009 - 07:00:50 EST
On Sat, Sep 05, 2009 at 10:28:37AM -0400, Theodore Tso wrote:
>
On Thu, Sep 03, 2009 at 01:49:14PM +0100, Mel Gorman wrote:
>
> >
>
> > This looks very similar to the kmemleak ext4 reports upon a mount. If
>
> > it is the same issue, which from the trace it seems it is, then this
>
> > is due to an extra kmalloc() allocation and this apparently will not
>
> > get fixed on 2.6.31 due to the closeness of the merge window and the
>
> > non-criticalness this issue has been deemed.
>
>
No, it's a different problem.
>
>
> I suspect the more pressing concern is why is this kmalloc() resulting in
>
> an order-5 allocation request? What size is the buffer being requested?
>
> Was that expected? What is the contents of /proc/slabinfo in case a buffer
>
> that should have required order-1 or order-2 is using a higher order for
>
> some reason.
>
>
It's allocating 68,000 bytes for the mb_history structure, which is
>
used for debugging purposes. That's why it's optional and we continue
>
if it's not allocated. We should fix it to use vmalloc()
You could call with kmalloc(FLAGS|GFP_NOWARN) with a fallback to
vmalloc() and a disable if vmalloc() fails as well. Maybe check out what
kernel/profile.c#profile_init() to allocate a large buffer and do something
similar?
>
and I'm
>
inclined to turn it off by default since it's not worth the overhead,
>
and most ext4 users won't find it useful or interesting.
>
I can't comment as I don't know what sort of debugging it's useful for.
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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