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epoll: convert max_user_watches to long

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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>
This commit is contained in:
Robin Holt 2011-01-12 17:00:01 -08:00 committed by Linus Torvalds
parent 65329bf46b
commit 52bd19f769
2 changed files with 13 additions and 9 deletions
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20
fs/eventpoll.c
View File

@ -217,7 +217,7 @@ struct ep_send_events_data {
* Configuration options available inside /proc/sys/fs/epoll/ * Configuration options available inside /proc/sys/fs/epoll/
*/ */
/* Maximum number of epoll watched descriptors, per user */ /* 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(). * This mutex is used to serialize ep_free() and eventpoll_release_file().
@ -240,16 +240,18 @@ static struct kmem_cache *pwq_cache __read_mostly;
#include <linux/sysctl.h> #include <linux/sysctl.h>
static int zero; static long zero;
static long long_max = LONG_MAX;
ctl_table epoll_table[] = { ctl_table epoll_table[] = {
{ {
.procname = "max_user_watches", .procname = "max_user_watches",
.data = &max_user_watches, .data = &max_user_watches,
.maxlen = sizeof(int), .maxlen = sizeof(max_user_watches),
.mode = 0644, .mode = 0644,
.proc_handler = proc_dointvec_minmax, .proc_handler = proc_doulongvec_minmax,
.extra1 = &zero, .extra1 = &zero,
.extra2 = &long_max,
}, },
{ } { }
}; };
@ -561,7 +563,7 @@ static int ep_remove(struct eventpoll *ep, struct epitem *epi)
/* At this point it is safe to free the eventpoll item */ /* At this point it is safe to free the eventpoll item */
kmem_cache_free(epi_cache, epi); kmem_cache_free(epi_cache, epi);
atomic_dec(&ep->user->epoll_watches); atomic_long_dec(&ep->user->epoll_watches);
return 0; return 0;
} }
@ -898,11 +900,12 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
{ {
int error, revents, pwake = 0; int error, revents, pwake = 0;
unsigned long flags; unsigned long flags;
long user_watches;
struct epitem *epi; struct epitem *epi;
struct ep_pqueue epq; struct ep_pqueue epq;
if (unlikely(atomic_read(&ep->user->epoll_watches) >= user_watches = atomic_long_read(&ep->user->epoll_watches);
max_user_watches)) if (unlikely(user_watches >= max_user_watches))
return -ENOSPC; return -ENOSPC;
if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL))) if (!(epi = kmem_cache_alloc(epi_cache, GFP_KERNEL)))
return -ENOMEM; return -ENOMEM;
@ -966,7 +969,7 @@ static int ep_insert(struct eventpoll *ep, struct epoll_event *event,
spin_unlock_irqrestore(&ep->lock, flags); 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 */ /* We have to call this outside the lock */
if (pwake) if (pwake)
@ -1426,6 +1429,7 @@ static int __init eventpoll_init(void)
*/ */
max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) / max_user_watches = (((si.totalram - si.totalhigh) / 25) << PAGE_SHIFT) /
EP_ITEM_COST; EP_ITEM_COST;
BUG_ON(max_user_watches < 0);
/* Initialize the structure used to perform safe poll wait head wake ups */ /* Initialize the structure used to perform safe poll wait head wake ups */
ep_nested_calls_init(&poll_safewake_ncalls); ep_nested_calls_init(&poll_safewake_ncalls);

2
include/linux/sched.h
View File

@ -683,7 +683,7 @@ struct user_struct {
atomic_t fanotify_listeners; atomic_t fanotify_listeners;
#endif #endif
#ifdef CONFIG_EPOLL #ifdef CONFIG_EPOLL
atomic_t epoll_watches; /* The number of file descriptors currently watched */ atomic_long_t epoll_watches; /* The number of file descriptors currently watched */
#endif #endif
#ifdef CONFIG_POSIX_MQUEUE #ifdef CONFIG_POSIX_MQUEUE
/* protected by mq_lock */ /* protected by mq_lock */