Hi, I ran into a panic while adding an interface to a bridge with a vxlan interface already attached to it, as it seems related mtu=9000.
I get the following panic info : [ 2482.419893] br100: port 2(vif1.1) entered blocking state [ 2482.425427] br100: port 2(vif1.1) entered forwarding state [ 2482.431797] skbuff: skb_over_panic: text:ffffffff816e4f78 len:40 put:40 head:ffff880146449000 data:ffff880146458fd0 tail:0xfff8 end:0xec0 dev:vif1.1 [ 2482.442891] ------------[ cut here ]------------ [ 2482.448254] kernel BUG at /srv/jenkins/workspace/workspace/hosting-xen-dom0-kernel/build/src/linux-4.9/net/core/skbuff.c:105! [ 2482.459009] invalid opcode: 0000 [#1] PREEMPT SMP [ 2482.464371] Modules linked in: [ 2482.469682] CPU: 19 PID: 1317 Comm: kworker/19:1 Not tainted 4.9.135-dom0-e9d15b2-x86_64-iaas #2 [ 2482.480362] Hardware name: Dell Inc. PowerEdge C8220/09N44V, BIOS 2.7.1 03/04/2015 [ 2482.491008] Workqueue: ipv6_addrconf addrconf_dad_work [ 2482.496380] task: ffff88017eef1a00 task.stack: ffffc90001fcc000 [ 2482.501785] RIP: e030:[<ffffffff815ed71f>] [<ffffffff815ed71f>] skb_panic+0x5f/0x70 [ 2482.512450] RSP: e02b:ffffc90001fcfba8 EFLAGS: 00010296 [ 2482.517817] RAX: 0000000000000088 RBX: ffff880117fb0800 RCX: 0000000000000000 [ 2482.528447] RDX: 0000000000000088 RSI: ffff880184cd03c8 RDI: ffff880184cd03c8 [ 2482.539085] RBP: ffffc90001fcfc00 R08: 00000000000006a8 R09: ffffffff81ea7359 [ 2482.549717] R10: ffff880180406f80 R11: 00000000000006a8 R12: ffff880147258cc0 [ 2482.560350] R13: ffffc90001fcfc20 R14: ffffffff81d13440 R15: 0000000000000000 [ 2482.570993] FS: 0000000000000000(0000) GS:ffff880184cc0000(0000) knlGS:0000000000000000 [ 2482.581646] CS: e033 DS: 0000 ES: 0000 CR0: 0000000080050033 [ 2482.587039] CR2: 00007f5b17f032b0 CR3: 0000000001c08000 CR4: 0000000000042660 [ 2482.597675] Stack: [ 2482.602958] ffff880146458fd0 000000000000fff8 0000000000000ec0 ffff88017f3f0000 [ 2482.613619] ffffffff815efa62 ffffffff816e4f78 ffff880117fb0800 ffffc90001fcfc20 [ 2482.624288] ffff880147258cc0 ffff88017f3f0000 ffff880146502000 ffffc90001fcfc68 [ 2482.634955] Call Trace: [ 2482.640254] [<ffffffff815efa62>] ? skb_put+0x42/0x50 [ 2482.645633] [<ffffffff816e4f78>] ? ip6_mc_hdr.constprop.36+0x58/0xd0 [ 2482.651045] [<ffffffff816e511a>] ? mld_newpack+0x12a/0x1e0 [ 2482.656421] [<ffffffff816e5257>] ? add_grhead.isra.28+0x87/0xa0 [ 2482.661825] [<ffffffff816e60d6>] ? add_grec+0x446/0x4c0 [ 2482.667198] [<ffffffff8108b06b>] ? __local_bh_enable_ip+0x1b/0xb0 [ 2482.672609] [<ffffffff816e6328>] ? mld_send_initial_cr.part.29+0x58/0xa0 [ 2482.678022] [<ffffffff816e83d6>] ? ipv6_mc_dad_complete+0x26/0x60 [ 2482.683441] [<ffffffff816cc2cf>] ? addrconf_dad_completed+0x29f/0x2c0 [ 2482.688850] [<ffffffff816e6b84>] ? ipv6_dev_mc_inc+0x194/0x2c0 [ 2482.694249] [<ffffffff816cc3ee>] ? addrconf_dad_work+0xfe/0x3d0 [ 2482.699650] [<ffffffff817484ed>] ? _raw_spin_unlock_irq+0xd/0x20 [ 2482.705052] [<ffffffff8109de12>] ? process_one_work+0x142/0x3e0 [ 2482.710453] [<ffffffff8109e112>] ? worker_thread+0x62/0x480 [ 2482.715848] [<ffffffff8109e0b0>] ? process_one_work+0x3e0/0x3e0 [ 2482.721256] [<ffffffff810a3472>] ? kthread+0xe2/0x100 [ 2482.726621] [<ffffffff81028701>] ? __switch_to+0x261/0x6b0 [ 2482.732006] [<ffffffff810a3390>] ? kthread_park+0x60/0x60 [ 2482.737379] [<ffffffff81748c37>] ? ret_from_fork+0x57/0x70 [ 2482.742761] Code: 00 00 48 89 44 24 10 8b 87 b0 00 00 00 48 89 44 24 08 48 8b 87 c0 00 00 00 48 c7 c7 50 8e a2 81 48 89 04 24 31 c0 e8 b5 07 b6 ff <0f> 0b 66 66 66 66 66 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 [ 2482.759199] RIP [<ffffffff815ed71f>] skb_panic+0x5f/0x70 [ 2482.764672] RSP <ffffc90001fcfba8> [ 2482.771186] ---[ end trace 6d0fe52ed049d841 ]--- [ 2482.776641] Kernel panic - not syncing: Fatal exception in interrupt [ 2482.861621] Kernel Offset: disabled I circumvented the bug by applying this patch: diff --git a/net/ipv6/mcast.c b/net/ipv6/mcast.c index 21f6deb2aec9..2762c3dcc883 100644 --- a/net/ipv6/mcast.c +++ b/net/ipv6/mcast.c @@ -1605,8 +1605,6 @@ static struct sk_buff *mld_newpack(struct inet6_dev *idev, unsigned int mtu) IPV6_TLV_PADN, 0 }; /* we assume size > sizeof(ra) here */ - /* limit our allocations to order-0 page */ - size = min_t(int, size, SKB_MAX_ORDER(0, 0)); skb = sock_alloc_send_skb(sk, size, 1, &err); if (!skb) The lines are introduced by commit 72e09ad107e78d69ff4d3b97a69f0aad2b77280f stating that "order-2 GRP_ATOMIC allocations are very unreliable" I then wonder if this statement is still relevant, or if such a patch would be acceptable to you. Regards, Nicolas