Messages in this thread Patch in this message | | | Date | Mon, 14 Dec 2009 20:24:23 +0100 | From | Eric Dumazet <> | Subject | Re: packet_sendmsg_spkt sleeping from invalid context |
| |
Le 14/12/2009 18:52, Frederic Weisbecker a écrit : > Hi, > > I don't know if it has been reported already. > I get the following warning on boot, with latest upstream tree: > > [ 32.776502] sched: BUG: sleeping function called from invalid context at mm/slab.c:3032 > [ 32.802173] sched: in_atomic(): 1, irqs_disabled(): 0, pid: 3555, name: dhclient3 > [ 32.821141] 1 lock held by dhclient3/3555: > [ 32.821147] #0: (rcu_read_lock){.+.+.+}, at: [<ffffffff815d177d>] packet_sendmsg_spkt+0x7d/0x2c0 > [ 32.821174] Pid: 3555, comm: dhclient3 Tainted: G W 2.6.32-tip+ #134 > [ 32.821181] Call Trace: > [ 32.821194] [<ffffffff810811c3>] ? __debug_show_held_locks+0x13/0x30 > [ 32.821207] [<ffffffff8103d6b8>] __might_sleep+0x118/0x140 > [ 32.821219] [<ffffffff81110c23>] kmem_cache_alloc+0x173/0x190 > [ 32.821231] [<ffffffff815483d9>] __alloc_skb+0x49/0x170 > [ 32.821241] [<ffffffff81542238>] sock_wmalloc+0x38/0x80 > [ 32.821250] [<ffffffff815d182b>] packet_sendmsg_spkt+0x12b/0x2c0 > [ 32.821260] [<ffffffff815d177d>] ? packet_sendmsg_spkt+0x7d/0x2c0 > [ 32.821272] [<ffffffff8153ded7>] sock_sendmsg+0x127/0x140 > [ 32.821285] [<ffffffff8106f4a0>] ? autoremove_wake_function+0x0/0x40 > [ 32.821297] [<ffffffff810f467b>] ? might_fault+0x7b/0xd0 > [ 32.821306] [<ffffffff810f467b>] ? might_fault+0x7b/0xd0 > [ 32.821318] [<ffffffff815401aa>] ? move_addr_to_kernel+0x6a/0x70 > [ 32.821328] [<ffffffff8154029f>] sys_sendto+0xef/0x120 > [ 32.821340] [<ffffffff81131479>] ? mntput_no_expire+0x29/0x110 > [ 32.821355] [<ffffffff810027db>] system_call_fastpath+0x16/0x1b >
Thanks for the report Frederic.
We could partly revert the original commit, but as we wanted to avoid touching device refcount, and af_packet might be the only real abuser, we could try following patch instead.
Thanks
[PATCH] packet: dont call sleeping function while holding rcu_read_lock()
commit 654d1f8a019dfa06d (packet: less dev_put() calls) introduced a problem, calling a potentially sleeping function from a rcu_read_lock() protected section.
Fix this by releasing lock before the sock_wmalloc() call. After skb allocation, we redo device lookup and appropriate tests.
Reported-by: Frederic Weisbecker <fweisbec@gmail.com> Signed-off-by: Eric Dumazet <eric.dumazet@gmail.com> --- net/packet/af_packet.c | 36 +++++++++++++----------------------- 1 file changed, 13 insertions(+), 23 deletions(-)
diff --git a/net/packet/af_packet.c b/net/packet/af_packet.c index 0205621..19ceadc 100644 --- a/net/packet/af_packet.c +++ b/net/packet/af_packet.c @@ -415,7 +415,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, { struct sock *sk = sock->sk; struct sockaddr_pkt *saddr = (struct sockaddr_pkt *)msg->msg_name; - struct sk_buff *skb; + struct sk_buff *skb = NULL; struct net_device *dev; __be16 proto = 0; int err; @@ -437,6 +437,7 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, */ saddr->spkt_device[13] = 0; +retry: rcu_read_lock(); dev = dev_get_by_name_rcu(sock_net(sk), saddr->spkt_device); err = -ENODEV; @@ -456,27 +457,21 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, if (len > dev->mtu + dev->hard_header_len) goto out_unlock; - err = -ENOBUFS; - skb = sock_wmalloc(sk, len + LL_RESERVED_SPACE(dev), 0, GFP_KERNEL); - - /* - * If the write buffer is full, then tough. At this level the user - * gets to deal with the problem - do your own algorithmic backoffs. - * That's far more flexible. - */ + if (!skb) { + size_t reserved = LL_RESERVED_SPACE(dev); - if (skb == NULL) - goto out_unlock; - - /* - * Fill it in - */ + rcu_read_unlock(); + skb = sock_wmalloc(sk, len + reserved, 0, GFP_KERNEL); + if (skb == NULL) + return -ENOBUFS; + skb_reserve(skb, reserved); + goto retry; + } /* FIXME: Save some space for broken drivers that write a * hard header at transmission time by themselves. PPP is the * notable one here. This should really be fixed at the driver level. */ - skb_reserve(skb, LL_RESERVED_SPACE(dev)); skb_reset_network_header(skb); /* Try to align data part correctly */ @@ -494,20 +489,15 @@ static int packet_sendmsg_spkt(struct kiocb *iocb, struct socket *sock, skb->priority = sk->sk_priority; skb->mark = sk->sk_mark; if (err) - goto out_free; - - /* - * Now send it - */ + goto out_unlock; dev_queue_xmit(skb); rcu_read_unlock(); return len; -out_free: - kfree_skb(skb); out_unlock: rcu_read_unlock(); + kfree_skb(skb); return err; } -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
| |