Commit 7d735b9a authored Jul 13, 2018 by Dominik Dingel Committed by Janosch Frank Jul 30, 2018

s390/mm: hugetlb pages within a gmap can not be freed



Guests backed by huge pages could theoretically free unused pages via
the diagnose 10 instruction. We currently don't allow that, so we
don't have to refault it once it's needed again.

Signed-off-by: Dominik Dingel <dingel@linux.vnet.ibm.com>
Reviewed-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Reviewed-by: David Hildenbrand <david@redhat.com>
Signed-off-by: Janosch Frank <frankja@linux.ibm.com>

parent bd096f64

arch/s390/mm/gmap.c

+6 −0

Original line number	Diff line number	Diff line
		@@ -706,6 +706,12 @@ void gmap_discard(struct gmap *gmap, unsigned long from, unsigned long to)
		vmaddr \|= gaddr & ~PMD_MASK;
		/* Find vma in the parent mm */
		vma = find_vma(gmap->mm, vmaddr);
		/*
		* We do not discard pages that are backed by
		* hugetlbfs, so we don't have to refault them.
		*/
		if (vma && is_vm_hugetlb_page(vma))
		continue;
		size = min(to - gaddr, PMD_SIZE - (gaddr & ~PMD_MASK));
		zap_page_range(vma, vmaddr, size);
		}