Re: IO errors after "block: remove bio_get_nr_vecs()"

[Jens Axboe]

On 12/21/2015 10:26 PM, Junichi Nomura wrote:
> On 12/22/15 12:59, Kent Overstreet 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
>
> blk_queue_bio() does split then bounce, which makes the segment
> counting based on pages before bouncing and could go wrong.

Good catch! The blk-mq parts aren't affected by this, the screw up only 
happened in the old IO path. I've added this with the appropriate 
tested-by from Artem, and CC stable and listed the commit that broke it:

commit 54efd50bfd873e2dbf784e0b21a8027ba4299a3e
Author: Kent Overstreet <kent.overstreet@xxxxxxxxx>
Date:   Thu Apr 23 22:37:18 2015 -0700

    block: make generic_make_request handle arbitrarily sized bios

Thanks to all involved in nailing this down, it'll go out shortly.

--
Jens Axboe

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