epoll: convert max_user_watches to long
On a 16TB machine, max_user_watches has an integer overflow. Convert it
to use a long and handle the associated fallout.
Signed-off-by: Robin Holt <holt@sgi.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Acked-by: Davide Libenzi <davidel@xmailserver.org>
Cc: Pekka Enberg <penberg@cs.helsinki.fi>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
diff --git a/fs/eventpoll.c b/fs/eventpoll.c
index 8cf0724..cc8a9b7 100644
--- a/fs/eventpoll.c
+++ b/fs/eventpoll.c
@@ -217,7 +217,7 @@
* Configuration options available inside /proc/sys/fs/epoll/
*/
/* Maximum number of epoll watched descriptors, per user */
-static int max_user_watches __read_mostly;
+static long max_user_watches __read_mostly;
/*
* This mutex is used to serialize ep_free() and eventpoll_release_file().
@@ -240,16 +240,18 @@
#include <linux/sysctl.h>
-static int zero;
+static long zero;
+static long long_max = LONG_MAX;
ctl_table epoll_table[] = {
{
.procname = "max_user_watches",
.data = &max_user_watches,
- .maxlen = sizeof(int),
+ .maxlen = sizeof(max_user_watches),
.mode = 0644,
- .proc_handler = proc_dointvec_minmax,
+ .proc_handler = proc_doulongvec_minmax,
.extra1 = &zero,
+ .extra2 = &long_max,
},
{ }
};
@@ -561,7 +563,7 @@
/* At this point it is safe to free the eventpoll item */
kmem_cache_free(epi_cache, epi);
- atomic_dec(&ep->user->epoll_watches);
+ atomic_long_dec(&ep->user->epoll_watches);
return 0;
}
@@ -898,11 +900,12 @@
{
int error, revents, pwake = 0;
unsigned long flags;
+ long user_watches;
struct epitem *epi;
struct ep_pqueue epq;
- if (unlikely(atomic_read(&ep->user->epoll_watches) >=
- max_user_watches))
+ user_watches = atomic_long_read(&ep->user->epoll_watches);
+ if (unlikely(user_watches >= max_user_watches))
return -ENOSPC;
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
return -ENOMEM;
@@ -966,7 +969,7 @@
spin_unlock_irqrestore(&ep->lock, flags);
- atomic_inc(&ep->user->epoll_watches);
+ atomic_long_inc(&ep->user->epoll_watches);
/* We have to call this outside the lock */
if (pwake)
@@ -1426,6 +1429,7 @@
*/
max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
EP_ITEM_COST;
+ BUG_ON(max_user_watches < 0);
/* Initialize the structure used to perform safe poll wait head wake ups */
ep_nested_calls_init(&poll_safewake_ncalls);