From mboxrd@z Thu Jan  1 00:00:00 1970
From: Kent Overstreet <kent.overstreet@gmail.com>
Subject: Re: IO errors after "block: remove bio_get_nr_vecs()"
Date: Mon, 21 Dec 2015 18:59:44 -0900
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To: Tejun Heo <tj@kernel.org>
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On Mon, Dec 21, 2015 at 04:08:11PM -0500, Tejun Heo wrote:

reproduced it with 32 bit pae:

> 1. Exclude memory above 4G line with boot param "max_addr=4G".

doesn't work - max_addr=1G doesn't work either

> 2. Disable highmem with "highmem=0".

works!

> 3. Try booting 64bit kernel.

works

Ok, so maybe it actually is PAE specific... but like you noted the block layer
works entirely in terms of pages so...

The one idea I can think of is - maybe BIOVEC_PHYS_MERGEABLE() is broken in PAE
mode? I am unfamiliar with anything PAE though.

Where does the ahci code consume the sglist?