Message ID | 20180928182410.slizlkx6fiwkyb76@codemonkey.org.uk |
---|---|
State | Changes Requested, archived |
Delegated to: | David Miller |
Headers | show |
Series | bond: take rcu lock in bond_poll_controller | expand |
On 09/28/2018 11:24 AM, Dave Jones wrote: > Callers of bond_for_each_slave_rcu are expected to hold the rcu lock, > otherwise a trace like below is shown > > WARNING: CPU: 2 PID: 179 at net/core/dev.c:6567 netdev_lower_get_next_private_rcu+0x34/0x40 > CPU: 2 PID: 179 Comm: kworker/u16:15 Not tainted 4.19.0-rc5-backup+ #1 > > > Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> > Signed-off-by: Dave Jones <davej@codemonkey.org.uk> > You forgot to change patch title.
On Fri, Sep 28, 2018 at 11:26 AM Dave Jones <davej@codemonkey.org.uk> wrote: > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > index 3219a2932463..4f9494381635 100644 > --- a/net/core/netpoll.c > +++ b/net/core/netpoll.c > @@ -330,6 +330,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, > /* It is up to the caller to keep npinfo alive. */ > struct netpoll_info *npinfo; > > + rcu_read_lock(); > lockdep_assert_irqs_disabled(); > > npinfo = rcu_dereference_bh(np->dev->npinfo); I think you probably need rcu_read_lock_bh() to satisfy rcu_deference_bh()...
On Fri, Sep 28, 2018 at 12:02 PM Cong Wang <xiyou.wangcong@gmail.com> wrote: > > On Fri, Sep 28, 2018 at 11:26 AM Dave Jones <davej@codemonkey.org.uk> wrote: > > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > > index 3219a2932463..4f9494381635 100644 > > --- a/net/core/netpoll.c > > +++ b/net/core/netpoll.c > > @@ -330,6 +330,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, > > /* It is up to the caller to keep npinfo alive. */ > > struct netpoll_info *npinfo; > > > > + rcu_read_lock(); > > lockdep_assert_irqs_disabled(); > > > > npinfo = rcu_dereference_bh(np->dev->npinfo); > > I think you probably need rcu_read_lock_bh() to satisfy > rcu_deference_bh()... But irq is disabled here, so not sure if rcu_read_lock_bh() could cause trouble... Interesting...
On Fri, Sep 28, 2018 at 12:03:22PM -0700, Cong Wang wrote: > On Fri, Sep 28, 2018 at 12:02 PM Cong Wang <xiyou.wangcong@gmail.com> wrote: > > > > On Fri, Sep 28, 2018 at 11:26 AM Dave Jones <davej@codemonkey.org.uk> wrote: > > > diff --git a/net/core/netpoll.c b/net/core/netpoll.c > > > index 3219a2932463..4f9494381635 100644 > > > --- a/net/core/netpoll.c > > > +++ b/net/core/netpoll.c > > > @@ -330,6 +330,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, > > > /* It is up to the caller to keep npinfo alive. */ > > > struct netpoll_info *npinfo; > > > > > > + rcu_read_lock(); > > > lockdep_assert_irqs_disabled(); > > > > > > npinfo = rcu_dereference_bh(np->dev->npinfo); > > > > I think you probably need rcu_read_lock_bh() to satisfy > > rcu_deference_bh()... > > But irq is disabled here, so not sure if rcu_read_lock_bh() > could cause trouble... Interesting... I was wondering for a moment why I never got a warning, then I remembered I disabled lockdep for that machine because nfs spews stuff. I'll doublecheck, and post v4. lol, this looked like a 2 minute fix at first. Dave
diff --git a/net/core/netpoll.c b/net/core/netpoll.c index 3219a2932463..4f9494381635 100644 --- a/net/core/netpoll.c +++ b/net/core/netpoll.c @@ -330,6 +330,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, /* It is up to the caller to keep npinfo alive. */ struct netpoll_info *npinfo; + rcu_read_lock(); lockdep_assert_irqs_disabled(); npinfo = rcu_dereference_bh(np->dev->npinfo); @@ -374,6 +375,7 @@ void netpoll_send_skb_on_dev(struct netpoll *np, struct sk_buff *skb, skb_queue_tail(&npinfo->txq, skb); schedule_delayed_work(&npinfo->tx_work,0); } + rcu_read_unlock(); } EXPORT_SYMBOL(netpoll_send_skb_on_dev);
Callers of bond_for_each_slave_rcu are expected to hold the rcu lock, otherwise a trace like below is shown WARNING: CPU: 2 PID: 179 at net/core/dev.c:6567 netdev_lower_get_next_private_rcu+0x34/0x40 CPU: 2 PID: 179 Comm: kworker/u16:15 Not tainted 4.19.0-rc5-backup+ #1 Workqueue: bond0 bond_mii_monitor RIP: 0010:netdev_lower_get_next_private_rcu+0x34/0x40 Code: 48 89 fb e8 fe 29 63 ff 85 c0 74 1e 48 8b 45 00 48 81 c3 c0 00 00 00 48 8b 00 48 39 d8 74 0f 48 89 45 00 48 8b 40 f8 5b 5d c3 <0f> 0b eb de 31 c0 eb f5 0f 1f 40 00 0f 1f 44 00 00 48 8> RSP: 0018:ffffc9000087fa68 EFLAGS: 00010046 RAX: 0000000000000000 RBX: ffff880429614560 RCX: 0000000000000000 RDX: 0000000000000001 RSI: 00000000ffffffff RDI: ffffffffa184ada0 RBP: ffffc9000087fa80 R08: 0000000000000001 R09: 0000000000000000 R10: ffffc9000087f9f0 R11: ffff880429798040 R12: ffff8804289d5980 R13: ffffffffa1511f60 R14: 00000000000000c8 R15: 00000000ffffffff FS: 0000000000000000(0000) GS:ffff88042f880000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f4b78fce180 CR3: 000000018180f006 CR4: 00000000001606e0 Call Trace: bond_poll_controller+0x52/0x170 netpoll_poll_dev+0x79/0x290 netpoll_send_skb_on_dev+0x158/0x2c0 netpoll_send_udp+0x2d5/0x430 write_ext_msg+0x1e0/0x210 console_unlock+0x3c4/0x630 vprintk_emit+0xfa/0x2f0 printk+0x52/0x6e ? __netdev_printk+0x12b/0x220 netdev_info+0x64/0x80 ? bond_3ad_set_carrier+0xe9/0x180 bond_select_active_slave+0x1fc/0x310 bond_mii_monitor+0x709/0x9b0 process_one_work+0x221/0x5e0 worker_thread+0x4f/0x3b0 kthread+0x100/0x140 ? process_one_work+0x5e0/0x5e0 ? kthread_delayed_work_timer_fn+0x90/0x90 ret_from_fork+0x24/0x30 Suggested-by: Cong Wang <xiyou.wangcong@gmail.com> Signed-off-by: Dave Jones <davej@codemonkey.org.uk>