4.9-stable review patch. If anyone has any objections, please let me know.
------------------
From: Vasily Gorbik <gor@xxxxxxxxxxxxx>
[ 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@xxxxxxxxxx>
Reviewed-by: Heiko Carstens <heiko.carstens@xxxxxxxxxx>
Signed-off-by: Vasily Gorbik <gor@xxxxxxxxxxxxx>
Signed-off-by: Martin Schwidefsky <schwidefsky@xxxxxxxxxx>
Signed-off-by: Sasha Levin <alexander.levin@xxxxxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
arch/s390/mm/pgalloc.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
--- a/arch/s390/mm/pgalloc.c
+++ b/arch/s390/mm/pgalloc.c
@@ -26,7 +26,7 @@ static struct ctl_table page_table_sysct
.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,
},
