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Date: Wed, 24 Oct 2007 11:14:47 +0200
From: Jens Axboe <jens.axboe@oracle.com>
To: Johannes Berg <johannes@sipsolutions.net>
Subject: Re: [PATCH] fix powerpc breakage in sg chaining code (again)
Message-ID: <20071024091446.GL14671@kernel.dk>
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On Tue, Oct 23 2007, Johannes Berg wrote:
> On Tue, 2007-10-23 at 23:00 +0200, Johannes Berg wrote:
> > Commit 33ff910f0f466184ffc3514628f18403dcd86761 fixed commit
> > 78bdc3106a877cfa50439fa66b52acbc4e7868df but the code that got put in
> > uses struct scatterlist->page which no longer exists since commit
> > 18dabf473e15850c0dbc8ff13ac1e2806d542c15 which requires using
> > sg_page(sg) instead of sg->page.
> 
> This doesn't help though, when I boot I get a NULL-pointer dereference
> that looks approximately like this:
> 
> NIP blk_rq_map_sg + 0x64/0x190
> LR ide_map_sg + 0x38/?
> Call trace:
> cfq_remove_request + 0x168 (unreliable)
> cfq_dispatch_request + 0x44
> ide_build_sglist + 0x38?
> pmac_ide_dma_setup + 0xa0?
> ide_do_rw_disk? + ?
> [...]
> 
> I can upload the picture I took but it's hardly readable (taken with my
> crappy cell phone)

I lost track - which kernel are you booting? This looks like something
that should be fixed, did you try 2.6.24-rc1?

-- 
Jens Axboe