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    Subject[Patch] 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>
    To: Andrew Morton <akpm@linux-foundation.org>
    Cc: "Eric W. Biederman" <ebiederm@xmission.com>
    Cc: Davide Libenzi <davidel@xmailserver.org>
    Cc: linux-kernel@vger.kernel.org
    Cc: Pekka Enberg <penberg@cs.helsinki.fi>

    ---

    fs/eventpoll.c | 20 ++++++++++++--------
    include/linux/sched.h | 2 +-
    2 files changed, 13 insertions(+), 9 deletions(-)

    Index: pv1010933/fs/eventpoll.c
    ===================================================================
    --- pv1010933.orig/fs/eventpoll.c 2010-10-27 14:04:44.000000000 -0500
    +++ pv1010933/fs/eventpoll.c 2010-10-27 14:07:50.211457551 -0500
    @@ -220,7 +220,7 @@ struct ep_send_events_data {
    * 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().
    @@ -243,16 +243,18 @@ static struct kmem_cache *pwq_cache __re

    #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,
    },
    { }
    };
    @@ -564,7 +566,7 @@ static int ep_remove(struct eventpoll *e
    /* 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;
    }
    @@ -900,11 +902,12 @@ static int ep_insert(struct eventpoll *e
    {
    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;
    @@ -968,7 +971,7 @@ static int ep_insert(struct eventpoll *e

    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)
    @@ -1422,6 +1425,7 @@ static int __init eventpoll_init(void)
    */
    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);
    Index: pv1010933/include/linux/sched.h
    ===================================================================
    --- pv1010933.orig/include/linux/sched.h 2010-10-27 14:04:44.000000000 -0500
    +++ pv1010933/include/linux/sched.h 2010-10-27 14:04:47.119415143 -0500
    @@ -666,7 +666,7 @@ struct user_struct {
    atomic_t inotify_devs; /* How many inotify devs does this user have opened? */
    #endif
    #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
    #ifdef CONFIG_POSIX_MQUEUE
    /* protected by mq_lock */


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