Commit 064d9efe authored by Nishanth Aravamudan's avatar Nishanth Aravamudan Committed by Linus Torvalds
Browse files

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

Signed-off-by: default avatarNishanth Aravamudan <>
Reported-by: default avatarMiles Lane <>
Cc: Adam Litke <>
Cc: David Gibson <>
Signed-off-by: default avatarAndrew Morton <>
Signed-off-by: default avatarLinus Torvalds <>
parent 2695a14d
......@@ -33,8 +33,8 @@ int hugetlb_reserve_pages(struct inode *inode, long from, long to);
void hugetlb_unreserve_pages(struct inode *inode, long offset, long freed);
extern unsigned long max_huge_pages;
extern unsigned long sysctl_overcommit_huge_pages;
extern unsigned long hugepages_treat_as_movable;
extern unsigned long nr_overcommit_huge_pages;
extern const unsigned long hugetlb_zero, hugetlb_infinity;
extern int sysctl_hugetlb_shm_group;
......@@ -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,
......@@ -24,14 +24,15 @@
const unsigned long hugetlb_zero = 0, hugetlb_infinity = ~0UL;
static unsigned long nr_huge_pages, free_huge_pages, resv_huge_pages;
static unsigned long surplus_huge_pages;
static unsigned long nr_overcommit_huge_pages;
unsigned long max_huge_pages;
unsigned long sysctl_overcommit_huge_pages;
static struct list_head hugepage_freelists[MAX_NUMNODES];
static unsigned int nr_huge_pages_node[MAX_NUMNODES];
static unsigned int free_huge_pages_node[MAX_NUMNODES];
static unsigned int surplus_huge_pages_node[MAX_NUMNODES];
static gfp_t htlb_alloc_mask = GFP_HIGHUSER;
unsigned long hugepages_treat_as_movable;
unsigned long nr_overcommit_huge_pages;
static int hugetlb_next_nid;
......@@ -609,8 +610,9 @@ int hugetlb_overcommit_handler(struct ctl_table *table, int write,
struct file *file, void __user *buffer,
size_t *length, loff_t *ppos)
proc_doulongvec_minmax(table, write, file, buffer, length, ppos);
nr_overcommit_huge_pages = sysctl_overcommit_huge_pages;
return 0;
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