forked from Minki/linux
drop_monitor: dont sleep in atomic context
drop_monitor calls several sleeping functions while in atomic context. BUG: sleeping function called from invalid context at mm/slub.c:943 in_atomic(): 1, irqs_disabled(): 0, pid: 2103, name: kworker/0:2 Pid: 2103, comm: kworker/0:2 Not tainted 3.5.0-rc1+ #55 Call Trace: [<ffffffff810697ca>] __might_sleep+0xca/0xf0 [<ffffffff811345a3>] kmem_cache_alloc_node+0x1b3/0x1c0 [<ffffffff8105578c>] ? queue_delayed_work_on+0x11c/0x130 [<ffffffff815343fb>] __alloc_skb+0x4b/0x230 [<ffffffffa00b0360>] ? reset_per_cpu_data+0x160/0x160 [drop_monitor] [<ffffffffa00b022f>] reset_per_cpu_data+0x2f/0x160 [drop_monitor] [<ffffffffa00b03ab>] send_dm_alert+0x4b/0xb0 [drop_monitor] [<ffffffff810568e0>] process_one_work+0x130/0x4c0 [<ffffffff81058249>] worker_thread+0x159/0x360 [<ffffffff810580f0>] ? manage_workers.isra.27+0x240/0x240 [<ffffffff8105d403>] kthread+0x93/0xa0 [<ffffffff816be6d4>] kernel_thread_helper+0x4/0x10 [<ffffffff8105d370>] ? kthread_freezable_should_stop+0x80/0x80 [<ffffffff816be6d0>] ? gs_change+0xb/0xb Rework the logic to call the sleeping functions in right context. Use standard timer/workqueue api to let system chose any cpu to perform the allocation and netlink send. Also avoid a loop if reset_per_cpu_data() cannot allocate memory : use mod_timer() to wait 1/10 second before next try. Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Neil Horman <nhorman@tuxdriver.com> Reviewed-by: Neil Horman <nhorman@tuxdriver.com> Signed-off-by: David S. Miller <davem@davemloft.net>
This commit is contained in:
Eric Dumazet
David S. Miller
parent
f8f5701bda
commit
bec4596b4e
@ -36,9 +36,6 @@
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#define TRACE_ON 1
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#define TRACE_OFF 0
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static void send_dm_alert(struct work_struct *unused);
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/*
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* Globals, our netlink socket pointer
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* and the work handle that will send up
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@ -48,11 +45,10 @@ static int trace_state = TRACE_OFF;
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static DEFINE_MUTEX(trace_state_mutex);
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struct per_cpu_dm_data {
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struct work_struct dm_alert_work;
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struct sk_buff __rcu *skb;
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atomic_t dm_hit_count;
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struct timer_list send_timer;
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int cpu;
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spinlock_t lock;
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struct sk_buff *skb;
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struct work_struct dm_alert_work;
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struct timer_list send_timer;
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};
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struct dm_hw_stat_delta {
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@ -78,13 +74,13 @@ static int dm_delay = 1;
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static unsigned long dm_hw_check_delta = 2*HZ;
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static LIST_HEAD(hw_stats_list);
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static void reset_per_cpu_data(struct per_cpu_dm_data *data)
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static struct sk_buff *reset_per_cpu_data(struct per_cpu_dm_data *data)
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{
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size_t al;
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struct net_dm_alert_msg *msg;
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struct nlattr *nla;
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struct sk_buff *skb;
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struct sk_buff *oskb = rcu_dereference_protected(data->skb, 1);
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unsigned long flags;
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al = sizeof(struct net_dm_alert_msg);
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al += dm_hit_limit * sizeof(struct net_dm_drop_point);
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@ -99,65 +95,40 @@ static void reset_per_cpu_data(struct per_cpu_dm_data *data)
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sizeof(struct net_dm_alert_msg));
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msg = nla_data(nla);
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memset(msg, 0, al);
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} else
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schedule_work_on(data->cpu, &data->dm_alert_work);
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/*
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* Don't need to lock this, since we are guaranteed to only
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* run this on a single cpu at a time.
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* Note also that we only update data->skb if the old and new skb
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* pointers don't match. This ensures that we don't continually call
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* synchornize_rcu if we repeatedly fail to alloc a new netlink message.
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*/
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if (skb != oskb) {
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rcu_assign_pointer(data->skb, skb);
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synchronize_rcu();
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atomic_set(&data->dm_hit_count, dm_hit_limit);
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} else {
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mod_timer(&data->send_timer, jiffies + HZ / 10);
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}
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spin_lock_irqsave(&data->lock, flags);
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swap(data->skb, skb);
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spin_unlock_irqrestore(&data->lock, flags);
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return skb;
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}
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static void send_dm_alert(struct work_struct *unused)
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static void send_dm_alert(struct work_struct *work)
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{
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struct sk_buff *skb;
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struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
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struct per_cpu_dm_data *data;
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WARN_ON_ONCE(data->cpu != smp_processor_id());
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data = container_of(work, struct per_cpu_dm_data, dm_alert_work);
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/*
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* Grab the skb we're about to send
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*/
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skb = rcu_dereference_protected(data->skb, 1);
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skb = reset_per_cpu_data(data);
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/*
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* Replace it with a new one
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*/
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reset_per_cpu_data(data);
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/*
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* Ship it!
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*/
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if (skb)
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genlmsg_multicast(skb, 0, NET_DM_GRP_ALERT, GFP_KERNEL);
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put_cpu_var(dm_cpu_data);
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}
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/*
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* This is the timer function to delay the sending of an alert
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* in the event that more drops will arrive during the
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* hysteresis period. Note that it operates under the timer interrupt
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* so we don't need to disable preemption here
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* hysteresis period.
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*/
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static void sched_send_work(unsigned long unused)
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static void sched_send_work(unsigned long _data)
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{
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struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
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struct per_cpu_dm_data *data = (struct per_cpu_dm_data *)_data;
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schedule_work_on(smp_processor_id(), &data->dm_alert_work);
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put_cpu_var(dm_cpu_data);
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schedule_work(&data->dm_alert_work);
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}
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static void trace_drop_common(struct sk_buff *skb, void *location)
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@ -167,33 +138,28 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
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struct nlattr *nla;
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int i;
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struct sk_buff *dskb;
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struct per_cpu_dm_data *data = &get_cpu_var(dm_cpu_data);
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struct per_cpu_dm_data *data;
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unsigned long flags;
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rcu_read_lock();
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dskb = rcu_dereference(data->skb);
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local_irq_save(flags);
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data = &__get_cpu_var(dm_cpu_data);
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spin_lock(&data->lock);
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dskb = data->skb;
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if (!dskb)
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goto out;
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if (!atomic_add_unless(&data->dm_hit_count, -1, 0)) {
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/*
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* we're already at zero, discard this hit
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*/
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goto out;
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}
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nlh = (struct nlmsghdr *)dskb->data;
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nla = genlmsg_data(nlmsg_data(nlh));
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msg = nla_data(nla);
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for (i = 0; i < msg->entries; i++) {
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if (!memcmp(&location, msg->points[i].pc, sizeof(void *))) {
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msg->points[i].count++;
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atomic_inc(&data->dm_hit_count);
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goto out;
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}
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}
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if (msg->entries == dm_hit_limit)
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goto out;
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/*
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* We need to create a new entry
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*/
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@ -205,13 +171,11 @@ static void trace_drop_common(struct sk_buff *skb, void *location)
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if (!timer_pending(&data->send_timer)) {
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data->send_timer.expires = jiffies + dm_delay * HZ;
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add_timer_on(&data->send_timer, smp_processor_id());
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add_timer(&data->send_timer);
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}
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out:
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rcu_read_unlock();
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put_cpu_var(dm_cpu_data);
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return;
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spin_unlock_irqrestore(&data->lock, flags);
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}
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static void trace_kfree_skb_hit(void *ignore, struct sk_buff *skb, void *location)
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@ -418,11 +382,11 @@ static int __init init_net_drop_monitor(void)
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for_each_possible_cpu(cpu) {
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data = &per_cpu(dm_cpu_data, cpu);
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data->cpu = cpu;
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INIT_WORK(&data->dm_alert_work, send_dm_alert);
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init_timer(&data->send_timer);
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data->send_timer.data = cpu;
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data->send_timer.data = (unsigned long)data;
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data->send_timer.function = sched_send_work;
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spin_lock_init(&data->lock);
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reset_per_cpu_data(data);
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}
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