Alexander Gordeev [off-list ref]:

Hi All,

This patch as commit e2c0b2368081b ("vmsplice: make vmsplice a trivial
wrapper for preadv2/pwritev2") in linux-next on s390 causes the selftest
tools/testing/selftests/mm/cow.c to hang:

# [RUN] vmsplice() + unmap in child ... with PTE-mapped THP (128 kB)

Recently there has been changes in THP area, so the problem is not
necessary linked to this patch per se.

Please, let me know if you need any additional information.

Thanks!

As well as I understand, this test uses vmsplice to pin pages.
I. e. if my patch lands, then this test should be rewriten to use
some other mechanism.

-- 
Askar Safin