Commits
Martin Schwidefsky committed a9809407f6b
s390/mm: fix vunmap vs finish_arch_post_lock_switch The vunmap_pte_range() function calls ptep_get_and_clear() without any locking. ptep_get_and_clear() uses ptep_xchg_lazy()/ptep_flush_direct() for the page table update. ptep_flush_direct requires that preemption is disabled, but without any locking this is not the case. If the kernel preempts the task while the attach_counter is increased an endless loop in finish_arch_post_lock_switch() will occur the next time the task is scheduled. Add explicit preempt_disable()/preempt_enable() calls to the relevant functions in arch/s390/mm/pgtable.c. Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>