s390/mm: correct allocate_pgste proc_handler callback

[ Upstream commit 5bedf8aa03c28cb8dc98bdd32a41b66d8f7d3eaa ]

Since proc_dointvec does not perform value range control,
proc_dointvec_minmax should be used to limit value range, which is
clearly intended here, as the internal representation of the value:

unsigned int alloc_pgste:1;

In fact it currently works, since we have

      mm->context.alloc_pgste = page_table_allocate_pgste || ...

... since commit 23fefe119ceb5 ("s390/kvm: avoid global config of vm.alloc_pgste=1")

Before that it was

       mm->context.alloc_pgste = page_table_allocate_pgste;

which was broken. That was introduced with commit 0b46e0a3ec0d7 ("s390/kvm:
remove delayed reallocation of page tables for KVM").

Fixes: 0b46e0a3ec0d7 ("s390/kvm: remove delayed reallocation of page tables for KVM")
Acked-by: Christian Borntraeger <borntraeger@de.ibm.com>
Reviewed-by: Heiko Carstens <heiko.carstens@de.ibm.com>
Signed-off-by: Vasily Gorbik <gor@linux.ibm.com>
Signed-off-by: Martin Schwidefsky <schwidefsky@de.ibm.com>
Signed-off-by: Sasha Levin <alexander.levin@microsoft.com>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>

diff --git a/arch/s390/mm/pgalloc.c b/arch/s390/mm/pgalloc.c
index e3bd562..76d89ee 100644 (file)
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -28,7 +28,7 @@ static struct ctl_table page_table_sysctl[] = {
                .data           = &page_table_allocate_pgste,
                .maxlen         = sizeof(int),
                .mode           = S_IRUGO | S_IWUSR,
-               .proc_handler   = proc_dointvec,
+               .proc_handler   = proc_dointvec_minmax,
                .extra1         = &page_table_allocate_pgste_min,
                .extra2         = &page_table_allocate_pgste_max,
        },