Ilya Dryomov [off-list ref] wrote:

quoted

Btw, is it feasible to use con->v2.out_iter_sendpage to apply
MSG_SPLICE_PAGES to the iterator to be transmitted as a whole?  It seems
to be set depending on iterator type.

I'm not sure I understand what you mean by "transmitted as a whole".
con->v2.out_iter_sendpage is set only when zerocopy is desired.  If the
underlying data is not guaranteed to remain stable, zerocopy behavior
is not safe.

I think I need to reinstate the per-page sendpage_ok() check here also -
though Al pointed out it isn't sufficiently exhaustive.  There are pages that
sendpage_ok() will return true on that you shouldn't be passing to sendpage().

I'll whip up a patch to partially revert this also.

David