Re: iSER initiator in 4.5 is unhappy..

[Christoph Hellwig <hch-wEGCiKHe2LqWVfeAwA7xHQ@public.gmane.org>]

On Thu, Apr 07, 2016 at 06:16:06PM +0300, Sagi Grimberg wrote:
> >>segment (which results in an extra page). The patch should fix the
> >>problem, however in this particular sg list I don't see the violation
> >>(counted 127 pages)...
> >
> >I counted 129 pages.
> >I will run some tests in our labs too.
> 
> If you did then that indicates the block layer violates
> its obligation to respect max_segments/max_hw_sectors?

I spent some time looking over the code and remembered an issue I
fixed for NVMf (which might explain why we're not seeing it there).

max_segments just means contiguous segments, not nessecarily 4k
pages.  For that we either need a small enough max_sectors_hw or set
a max_segment_size of 4k, otherwise we might get 128 block segments,
but due to lacking alignment they'll expand to 129 pages.
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