netdev - Re: [PATCH][RFC] network splice receive

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Message-ID: <20070605114545.GC9909@kernel.dk>
Date:	Tue, 5 Jun 2007 13:45:46 +0200
From:	Jens Axboe <jens.axboe@...cle.com>
To:	netdev@...r.kernel.org
Subject: Re: [PATCH][RFC] network splice receive

On Tue, Jun 05 2007, Jens Axboe wrote:
> Seems to work reasonably well for me, sometimes I do see small ranges
> inside the output file that are not correct, but I haven't been able to
> reproduce today. I think it has to do with page reuse, hence the
> NET_COPY_SPLICE ifdef that you can enable to just plain copy the data
> instead of referencing it.

I managed to reproduce. It's segments of 68-80 bytes beyond corrupt in
the middle of the out, and there might be 1-3 of such occurences in the
30mb file I tested with. The first 16 bytes of the corruption are always
the same:

0000 1800 4ff3 937f e000 6381 7275 0008

Perhaps that hex pattern rings a bell with someone intimate with the
networking. The remaining wrong bytes don't seem to have anything in
common.

Slab poisoning doesn't change the pattern, so it's not use-after-free.

-- 
Jens Axboe

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