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Date: Tue, 14 Aug 2012 18:28:16 +0800
From: Cong Wang <amwang@...hat.com>
To: netdev@...r.kernel.org
Cc: "David S. Miller" <davem@...emloft.net>,
John Fastabend <john.r.fastabend@...el.com>,
Greg Rose <gregory.v.rose@...el.com>,
Thomas Graf <tgraf@...g.ch>,
Eric Dumazet <edumazet@...gle.com>,
Ben Hutchings <bhutchings@...arflare.com>,
Cong Wang <amwang@...hat.com>
Subject: [Patch] net: allow calling rtmsg_ifinfo() in atomic
(Against net tree.)
When running 'systemctl restart network.service', I got the following
warning:
[ 1123.199677]
[ 1123.310275] ===============================
[ 1123.442202] [ INFO: suspicious RCU usage. ]
[ 1123.558207] 3.6.0-rc1+ #109 Not tainted
[ 1123.665204] -------------------------------
[ 1123.768254] include/linux/rcupdate.h:430 Illegal context switch in RCU read-side critical section!
[ 1123.992320]
[ 1123.992320] other info that might help us debug this:
[ 1123.992320]
[ 1124.307382]
[ 1124.307382] rcu_scheduler_active = 1, debug_locks = 0
[ 1124.522220] 2 locks held by sysctl/5710:
[ 1124.648364] #0: (rtnl_mutex){+.+.+.}, at: [<ffffffff81768498>] rtnl_trylock+0x15/0x17
[ 1124.882211] #1: (rcu_read_lock){.+.+.+}, at: [<ffffffff81871df8>] rcu_lock_acquire+0x0/0x29
[ 1125.085209]
[ 1125.085209] stack backtrace:
[ 1125.332213] Pid: 5710, comm: sysctl Not tainted 3.6.0-rc1+ #109
[ 1125.441291] Call Trace:
[ 1125.545281] [<ffffffff8109d915>] lockdep_rcu_suspicious+0x109/0x112
[ 1125.667212] [<ffffffff8107c240>] rcu_preempt_sleep_check+0x45/0x47
[ 1125.781838] [<ffffffff8107c260>] __might_sleep+0x1e/0x19b
[ 1125.900306] [<ffffffff8113e4a2>] slab_pre_alloc_hook+0x2d/0x38
[ 1126.012217] [<ffffffff817508f4>] ? __alloc_skb+0x4c/0x1a2
[ 1126.115156] [<ffffffff811411ea>] kmem_cache_alloc_node+0x2c/0x1c2
[ 1126.260520] [<ffffffff8109cae1>] ? lock_is_held+0x8a/0x95
[ 1126.391261] [<ffffffff817508f4>] ? __alloc_skb+0x4c/0x1a2
[ 1126.515221] [<ffffffff817508f4>] __alloc_skb+0x4c/0x1a2
[ 1126.615272] [<ffffffff8176778b>] ? if_nlmsg_size+0x164/0x19b
[ 1126.741293] [<ffffffff8176718e>] nlmsg_new+0x14/0x16
[ 1126.863267] [<ffffffff8176994d>] rtmsg_ifinfo+0x3b/0xcd
[ 1126.982196] [<ffffffff8109cae1>] ? lock_is_held+0x8a/0x95
[ 1127.102201] [<ffffffff81769a0f>] rtnetlink_event+0x30/0x34
[ 1127.229490] [<ffffffff8198a241>] notifier_call_chain+0x96/0xcd
[ 1127.338260] [<ffffffff810760b3>] raw_notifier_call_chain+0x14/0x16
[ 1127.445223] [<ffffffff81757ac5>] call_netdevice_notifiers+0x4a/0x4f
[ 1127.560195] [<ffffffff81757ffb>] netdev_features_change+0x16/0x18
[ 1127.668273] [<ffffffff8175e0ee>] netdev_update_features+0x20/0x25
[ 1127.772188] [<ffffffff8175e125>] dev_disable_lro+0x32/0x6b
[ 1127.885174] [<ffffffff81872d26>] dev_forward_change+0x30/0xcb
[ 1128.013214] [<ffffffff818738c4>] addrconf_forward_change+0x85/0xc5
[ 1128.118328] [<ffffffff818739bc>] addrconf_sysctl_forward+0xb8/0x108
[ 1128.278964] [<ffffffff81873904>] ? addrconf_forward_change+0xc5/0xc5
[ 1128.383230] [<ffffffff811af269>] proc_sys_call_handler+0x8a/0xb8
[ 1128.475407] [<ffffffff811af2ab>] proc_sys_write+0x14/0x16
[ 1128.578263] [<ffffffff81152a9e>] vfs_write+0xaf/0xf6
[ 1128.674728] [<ffffffff81153edf>] ? fget_light+0x3a/0xa1
[ 1128.790492] [<ffffffff81152c99>] sys_write+0x4d/0x74
[ 1128.902165] [<ffffffff8112040e>] ? do_anonymous_page+0x162/0x1d6
[ 1129.017203] [<ffffffff8198dea9>] system_call_fastpath+0x16/0x1b
This is due to that we call rtmsg_ifinfo() with RCU read lock held,
and because rtmsg_ifinfo() may block, this is invalid.
This patch fixes it by allowing callees to specify GFP when
calling it. In this case, netdev_features_change() calls it
with GFP_ATOMIC.
Cc: "David S. Miller" <davem@...emloft.net>
Cc: John Fastabend <john.r.fastabend@...el.com>
Cc: Greg Rose <gregory.v.rose@...el.com>
Cc: Thomas Graf <tgraf@...g.ch>
Cc: Eric Dumazet <edumazet@...gle.com>
Cc: Ben Hutchings <bhutchings@...arflare.com>
Signed-off-by: Cong Wang <amwang@...hat.com>
---
diff --git a/include/linux/rtnetlink.h b/include/linux/rtnetlink.h
index db71c4a..8d5b0b0 100644
--- a/include/linux/rtnetlink.h
+++ b/include/linux/rtnetlink.h
@@ -621,7 +621,8 @@ extern int rtnetlink_put_metrics(struct sk_buff *skb, u32 *metrics);
extern int rtnl_put_cacheinfo(struct sk_buff *skb, struct dst_entry *dst,
u32 id, long expires, u32 error);
-extern void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change);
+extern void rtmsg_ifinfo(int type, struct net_device *dev, unsigned change,
+ gfp_t flags);
/* RTNL is used as a global lock for all changes to network configuration */
extern void rtnl_lock(void);
diff --git a/net/core/dev.c b/net/core/dev.c
index a39354e..8c44e4c 100644
--- a/net/core/dev.c
+++ b/net/core/dev.c
@@ -1089,6 +1089,7 @@ int dev_set_alias(struct net_device *dev, const char *alias, size_t len)
void netdev_features_change(struct net_device *dev)
{
call_netdevice_notifiers(NETDEV_FEAT_CHANGE, dev);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_ATOMIC);
}
EXPORT_SYMBOL(netdev_features_change);
@@ -1104,7 +1105,7 @@ void netdev_state_change(struct net_device *dev)
{
if (dev->flags & IFF_UP) {
call_netdevice_notifiers(NETDEV_CHANGE, dev);
- rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
}
}
EXPORT_SYMBOL(netdev_state_change);
@@ -1204,7 +1205,7 @@ int dev_open(struct net_device *dev)
if (ret < 0)
return ret;
- rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
call_netdevice_notifiers(NETDEV_UP, dev);
return ret;
@@ -1277,7 +1278,7 @@ static int dev_close_many(struct list_head *head)
__dev_close_many(head);
list_for_each_entry(dev, head, unreg_list) {
- rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, IFF_UP|IFF_RUNNING, GFP_KERNEL);
call_netdevice_notifiers(NETDEV_DOWN, dev);
}
@@ -4482,7 +4483,7 @@ int netdev_set_bond_master(struct net_device *slave, struct net_device *master)
else
slave->flags &= ~IFF_SLAVE;
- rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE);
+ rtmsg_ifinfo(RTM_NEWLINK, slave, IFF_SLAVE, GFP_KERNEL);
return 0;
}
EXPORT_SYMBOL(netdev_set_bond_master);
@@ -4776,7 +4777,7 @@ int dev_change_flags(struct net_device *dev, unsigned int flags)
changes = old_flags ^ dev->flags;
if (changes)
- rtmsg_ifinfo(RTM_NEWLINK, dev, changes);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, changes, GFP_KERNEL);
__dev_notify_flags(dev, old_flags);
return ret;
@@ -5289,7 +5290,7 @@ static void rollback_registered_many(struct list_head *head)
if (!dev->rtnl_link_ops ||
dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
- rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
+ rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
/*
* Flush the unicast and multicast chains
@@ -5643,7 +5644,7 @@ int register_netdevice(struct net_device *dev)
*/
if (!dev->rtnl_link_ops ||
dev->rtnl_link_state == RTNL_LINK_INITIALIZED)
- rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
out:
return ret;
@@ -6227,7 +6228,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
*/
call_netdevice_notifiers(NETDEV_UNREGISTER, dev);
call_netdevice_notifiers(NETDEV_UNREGISTER_BATCH, dev);
- rtmsg_ifinfo(RTM_DELLINK, dev, ~0U);
+ rtmsg_ifinfo(RTM_DELLINK, dev, ~0U, GFP_KERNEL);
/*
* Flush the unicast and multicast chains
@@ -6260,7 +6261,7 @@ int dev_change_net_namespace(struct net_device *dev, struct net *net, const char
* Prevent userspace races by waiting until the network
* device is fully setup before sending notifications.
*/
- rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
synchronize_net();
err = 0;
diff --git a/net/core/rtnetlink.c b/net/core/rtnetlink.c
index 2c5a0a0..ab214ce 100644
--- a/net/core/rtnetlink.c
+++ b/net/core/rtnetlink.c
@@ -1631,7 +1631,7 @@ int rtnl_configure_link(struct net_device *dev, const struct ifinfomsg *ifm)
}
dev->rtnl_link_state = RTNL_LINK_INITIALIZED;
- rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, ~0U, GFP_KERNEL);
__dev_notify_flags(dev, old_flags);
return 0;
@@ -1962,14 +1962,14 @@ static int rtnl_dump_all(struct sk_buff *skb, struct netlink_callback *cb)
return skb->len;
}
-void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change)
+void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change, gfp_t flags)
{
struct net *net = dev_net(dev);
struct sk_buff *skb;
int err = -ENOBUFS;
size_t if_info_size;
- skb = nlmsg_new((if_info_size = if_nlmsg_size(dev, 0)), GFP_KERNEL);
+ skb = nlmsg_new((if_info_size = if_nlmsg_size(dev, 0)), flags);
if (skb == NULL)
goto errout;
@@ -1980,7 +1980,7 @@ void rtmsg_ifinfo(int type, struct net_device *dev, unsigned int change)
kfree_skb(skb);
goto errout;
}
- rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, GFP_KERNEL);
+ rtnl_notify(skb, net, 0, RTNLGRP_LINK, NULL, flags);
return;
errout:
if (err < 0)
@@ -2359,9 +2359,10 @@ static int rtnetlink_event(struct notifier_block *this, unsigned long event, voi
case NETDEV_UNREGISTER_BATCH:
case NETDEV_RELEASE:
case NETDEV_JOIN:
+ case NETDEV_FEAT_CHANGE:
break;
default:
- rtmsg_ifinfo(RTM_NEWLINK, dev, 0);
+ rtmsg_ifinfo(RTM_NEWLINK, dev, 0, GFP_KERNEL);
break;
}
return NOTIFY_DONE;
--
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