hugetlb: add locking for overcommit sysctl
When I replaced hugetlb_dynamic_pool with nr_overcommit_hugepages I used
proc_doulongvec_minmax() directly. However, hugetlb.c's locking rules
require that all counter modifications occur under the hugetlb_lock. Add a
callback into the hugetlb code similar to the one for nr_hugepages. Grab
the lock around the manipulation of nr_overcommit_hugepages in
proc_doulongvec_minmax().
Signed-off-by: Nishanth Aravamudan <nacc@us.ibm.com>
Acked-by: Adam Litke <agl@us.ibm.com>
Cc: David Gibson <david@gibson.dropbear.id.au>
Cc: William Lee Irwin III <wli@holomorphy.com>
Cc: <stable@kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/include/linux/hugetlb.h b/include/linux/hugetlb.h
index 30d606a..7ca198b 100644
--- a/include/linux/hugetlb.h
+++ b/include/linux/hugetlb.h
@@ -17,6 +17,7 @@
}
int hugetlb_sysctl_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
+int hugetlb_overcommit_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
int hugetlb_treat_movable_handler(struct ctl_table *, int, struct file *, void __user *, size_t *, loff_t *);
int copy_hugetlb_page_range(struct mm_struct *, struct mm_struct *, struct vm_area_struct *);
int follow_hugetlb_page(struct mm_struct *, struct vm_area_struct *, struct page **, struct vm_area_struct **, unsigned long *, int *, int, int);
diff --git a/kernel/sysctl.c b/kernel/sysctl.c
index 8c98d81..9dadc9d 100644
--- a/kernel/sysctl.c
+++ b/kernel/sysctl.c
@@ -982,7 +982,7 @@
.data = &nr_overcommit_huge_pages,
.maxlen = sizeof(nr_overcommit_huge_pages),
.mode = 0644,
- .proc_handler = &proc_doulongvec_minmax,
+ .proc_handler = &hugetlb_overcommit_handler,
},
#endif
{
diff --git a/mm/hugetlb.c b/mm/hugetlb.c
index 1a56420..d9a3803 100644
--- a/mm/hugetlb.c
+++ b/mm/hugetlb.c
@@ -605,6 +605,16 @@
return 0;
}
+int hugetlb_overcommit_handler(struct ctl_table *table, int write,
+ struct file *file, void __user *buffer,
+ size_t *length, loff_t *ppos)
+{
+ spin_lock(&hugetlb_lock);
+ proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
+ spin_unlock(&hugetlb_lock);
+ return 0;
+}
+
#endif /* CONFIG_SYSCTL */
int hugetlb_report_meminfo(char *buf)