hugetlb: fix overcommit locking

proc_doulongvec_minmax() calls copy_to_user()/copy_from_user(), so we can't
hold hugetlb_lock over the call.  Use a dummy variable to store the sysctl
result, like in hugetlb_sysctl_handler(), then grab the lock to update
nr_overcommit_huge_pages.

Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Reported-by: Miles Lane <miles.lane@gmail.com>
Cc: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 2 insertions, 2 deletions

diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 924c674b76ea..8b7e95411795 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -978,8 +978,8 @@ static struct ctl_table vm_table[] = {
         {
                 .ctl_name       = CTL_UNNUMBERED,
                 .procname       = "nr_overcommit_hugepages",
-                .data           = &nr_overcommit_huge_pages,
-                .maxlen         = sizeof(nr_overcommit_huge_pages),
+                .data           = &sysctl_overcommit_huge_pages,
+                .maxlen         = sizeof(sysctl_overcommit_huge_pages),
                 .mode           = 0644,
                 .proc_handler   = &hugetlb_overcommit_handler,
         },