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

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:

quoted

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.