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Date: Wed, 31 Oct 2001 09:33:53 +0100
From: Jens Axboe <axboe@suse.de>
To: Dan Maas <dmaas@dcine.com>
Cc: "David S. Miller" <davem@redhat.com>, linux-kernel@vger.kernel.org
Subject: Re: SCSI tape crashes (was Re: BUG() in asm/pci.h:142 with 2.4.13)
Message-ID: <20011031093353.F631@suse.de>
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On Tue, Oct 30 2001, Dan Maas wrote:
> > Can people try out this patch?  I believe this will fix the bug.
> > + tb->sg[0].page = NULL;
> >   if (tb->sg[segs].address == NULL) {
> 
> For the sake of making this clear to other kernel hackers (I got bitten by
> it too) - starting with 2.4.13 you must zero out the fields of struct
> scatterlist that you are not using. i.e. it is no longer sufficient to
> simply set sg.address and sg.length, because junk might still be present in
> the new sg.page field, and pci_map_*() will BUG() if both sg.address and
> sg.page are non-zero.

True, perhaps we should add a init_sg or something like that.

-- 
Jens Axboe

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