kmap_coherent needs disabled preemption to not schedule in the critical
section, just like kmap_coherent on mips and kmap_atomic in general.
Fixes: 8222dbe21e79 "sched/preempt, mm/fault: Decouple preemption from the page fault logic"
Reported-by: Hans Verkuil <hverkuil@xs4all.nl>
Signed-off-by: David Hildenbrand <dahi@linux.vnet.ibm.com>
Tested-by: Hans Verkuil <hans.verkuil@cisco.com>
Signed-off-by: Rich Felker <dalias@libc.org>
 
        BUG_ON(!test_bit(PG_dcache_clean, &page->flags));
 
+       preempt_disable();
        pagefault_disable();
 
        idx = FIX_CMAP_END -
        }
 
        pagefault_enable();
+       preempt_enable();
 }