[PATCH v2 1/1] block: blk-merge: don't merge the pages with non-contiguous descriptors

[Russell King - ARM Linux]

On Thu, Jan 17, 2013 at 11:01:47AM +0000, James Bottomley wrote:
> On Thu, 2013-01-17 at 10:47 +0000, Russell King - ARM Linux wrote:
> > Also, couldn't the addition of the scatterlist offset to the page also
> > be buggy too?
> 
> No, fortunately, offset must be within the first page from the point of
> view of block generated sg lists.  As long as nothing within arm
> violates this, it should be a safe assumption ... although the code
> seems to assume otherwise.

Are you absolutely sure about that?  I believe I have seen cases where
that has been violated in the past, though it was many years ago.