Hi Greg: Please don't add this patch to the stable tree, I still discus with Paul about this problem and maybe original solution is not the best one, I need more time to check, thanks. Ding On 2016/12/3 16:53, gregkh@xxxxxxxxxxxxxxxxxxx wrote: > > This is a note to let you know that I've just added the patch titled > > rcu: Fix soft lockup for rcu_nocb_kthread > > to the 4.8-stable tree which can be found at: > http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary > > The filename of the patch is: > rcu-fix-soft-lockup-for-rcu_nocb_kthread.patch > and it can be found in the queue-4.8 subdirectory. > > If you, or anyone else, feels it should not be added to the stable tree, > please let <stable@xxxxxxxxxxxxxxx> know about it. > > >>From bedc1969150d480c462cdac320fa944b694a7162 Mon Sep 17 00:00:00 2001 > From: Ding Tianhong <dingtianhong@xxxxxxxxxx> > Date: Wed, 15 Jun 2016 15:27:36 +0800 > Subject: rcu: Fix soft lockup for rcu_nocb_kthread > > From: Ding Tianhong <dingtianhong@xxxxxxxxxx> > > commit bedc1969150d480c462cdac320fa944b694a7162 upstream. > > Carrying out the following steps results in a softlockup in the > RCU callback-offload (rcuo) kthreads: > > 1. Connect to ixgbevf, and set the speed to 10Gb/s. > 2. Use ifconfig to bring the nic up and down repeatedly. > > [ 317.005148] IPv6: ADDRCONF(NETDEV_CHANGE): eth2: link becomes ready > [ 368.106005] BUG: soft lockup - CPU#1 stuck for 22s! [rcuos/1:15] > [ 368.106005] Hardware name: Bochs Bochs, BIOS Bochs 01/01/2011 > [ 368.106005] task: ffff88057dd8a220 ti: ffff88057dd9c000 task.ti: ffff88057dd9c000 > [ 368.106005] RIP: 0010:[<ffffffff81579e04>] [<ffffffff81579e04>] fib_table_lookup+0x14/0x390 > [ 368.106005] RSP: 0018:ffff88061fc83ce8 EFLAGS: 00000286 > [ 368.106005] RAX: 0000000000000001 RBX: 00000000020155c0 RCX: 0000000000000001 > [ 368.106005] RDX: ffff88061fc83d50 RSI: ffff88061fc83d70 RDI: ffff880036d11a00 > [ 368.106005] RBP: ffff88061fc83d08 R08: 0000000000000001 R09: 0000000000000000 > [ 368.106005] R10: ffff880036d11a00 R11: ffffffff819e0900 R12: ffff88061fc83c58 > [ 368.106005] R13: ffffffff816154dd R14: ffff88061fc83d08 R15: 00000000020155c0 > [ 368.106005] FS: 0000000000000000(0000) GS:ffff88061fc80000(0000) knlGS:0000000000000000 > [ 368.106005] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > [ 368.106005] CR2: 00007f8c2aee9c40 CR3: 000000057b222000 CR4: 00000000000407e0 > [ 368.106005] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000 > [ 368.106005] DR3: 0000000000000000 DR6: 00000000ffff0ff0 DR7: 0000000000000400 > [ 368.106005] Stack: > [ 368.106005] 00000000010000c0 ffff88057b766000 ffff8802e380b000 ffff88057af03e00 > [ 368.106005] ffff88061fc83dc0 ffffffff815349a6 ffff88061fc83d40 ffffffff814ee146 > [ 368.106005] ffff8802e380af00 00000000e380af00 ffffffff819e0900 020155c0010000c0 > [ 368.106005] Call Trace: > [ 368.106005] <IRQ> > [ 368.106005] > [ 368.106005] [<ffffffff815349a6>] ip_route_input_noref+0x516/0xbd0 > [ 368.106005] [<ffffffff814ee146>] ? skb_release_data+0xd6/0x110 > [ 368.106005] [<ffffffff814ee20a>] ? kfree_skb+0x3a/0xa0 > [ 368.106005] [<ffffffff8153698f>] ip_rcv_finish+0x29f/0x350 > [ 368.106005] [<ffffffff81537034>] ip_rcv+0x234/0x380 > [ 368.106005] [<ffffffff814fd656>] __netif_receive_skb_core+0x676/0x870 > [ 368.106005] [<ffffffff814fd868>] __netif_receive_skb+0x18/0x60 > [ 368.106005] [<ffffffff814fe4de>] process_backlog+0xae/0x180 > [ 368.106005] [<ffffffff814fdcb2>] net_rx_action+0x152/0x240 > [ 368.106005] [<ffffffff81077b3f>] __do_softirq+0xef/0x280 > [ 368.106005] [<ffffffff8161619c>] call_softirq+0x1c/0x30 > [ 368.106005] <EOI> > [ 368.106005] > [ 368.106005] [<ffffffff81015d95>] do_softirq+0x65/0xa0 > [ 368.106005] [<ffffffff81077174>] local_bh_enable+0x94/0xa0 > [ 368.106005] [<ffffffff81114922>] rcu_nocb_kthread+0x232/0x370 > [ 368.106005] [<ffffffff81098250>] ? wake_up_bit+0x30/0x30 > [ 368.106005] [<ffffffff811146f0>] ? rcu_start_gp+0x40/0x40 > [ 368.106005] [<ffffffff8109728f>] kthread+0xcf/0xe0 > [ 368.106005] [<ffffffff810971c0>] ? kthread_create_on_node+0x140/0x140 > [ 368.106005] [<ffffffff816147d8>] ret_from_fork+0x58/0x90 > [ 368.106005] [<ffffffff810971c0>] ? kthread_create_on_node+0x140/0x140 > > ==================================cut here============================== > > It turns out that the rcuos callback-offload kthread is busy processing > a very large quantity of RCU callbacks, and it is not reliquishing the > CPU while doing so. This commit therefore adds an cond_resched_rcu_qs() > within the loop to allow other tasks to run. > > Signed-off-by: Ding Tianhong <dingtianhong@xxxxxxxxxx> > [ paulmck: Substituted cond_resched_rcu_qs for cond_resched. ] > Signed-off-by: Paul E. McKenney <paulmck@xxxxxxxxxxxxxxxxxx> > Cc: Dhaval Giani <dhaval.giani@xxxxxxxxxx> > Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx> > > --- > kernel/rcu/tree_plugin.h | 1 + > 1 file changed, 1 insertion(+) > > --- a/kernel/rcu/tree_plugin.h > +++ b/kernel/rcu/tree_plugin.h > @@ -2173,6 +2173,7 @@ static int rcu_nocb_kthread(void *arg) > cl++; > c++; > local_bh_enable(); > + cond_resched_rcu_qs(); > list = next; > } > trace_rcu_batch_end(rdp->rsp->name, c, !!list, 0, 0, 1); > > > Patches currently in stable-queue which might be from dingtianhong@xxxxxxxxxx are > > queue-4.8/rcu-fix-soft-lockup-for-rcu_nocb_kthread.patch > > . > -- To unsubscribe from this list: send the line "unsubscribe stable" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html