Pull s390 fixes from Martin Schwidefsky:
"A few more changes for v4.18:
- wire up the two new system calls io_pgetevents and rseq
- fix a register corruption in the expolines code for machines
without EXRL
- drastically reduce the memory utilization of the dasd driver
- fix reference counting for KVM page table pages"
* 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/s390/linux:
s390: wire up rseq system call
s390: wire up io_pgetevents system call
s390/mm: fix refcount usage for 4K pgste
s390/dasd: reduce the default queue depth and nr of hardware queues
s390: Correct register corruption in critical section cleanup