Hi, With linux-4.19.1 I'm seeing regular kernel panics since this night with uptime of 5 to 30 minutes in between. System is not heavily loaded. With the following trace (transcribed): Call Trace: <IRQ> nf_conncount_count+0x48c/0x4f0 ? nf_ct_ext_add+0x80/0x170 connlimit_mt+0xa1/0x1a0 ? ipt_do_table+0x245/0x420 ipt_do_table+0x245/0x420 nf_hook_slow+0x3e/0xb0 ip_local_deliver+0x9a/0xd0 ? ip_sublist_rcv_finish+0x60/0x60 ip_rcv+0x8f/0xb0 ? ip_rcv_finish_core.isra.17+0x300/0x300 __netif_receive_skb_internal+0x4d/0x70 netif_receive_skb_internal+0x3e/0xd0 napi_gro_receive+0x6a/0x80 receive_buf+0x294/0xe40 ? detach_buf+0x63/0x100 virtnet_poll+0xba/0x2f0 net_rx_action+0x137/0x330 __do_softirq+0xd6/0x238 irq_exit+0xc6/0xd0 do_IRQ+0x78/0xd0 common_interrupt+0xf/xf </IRQ> RIP: :native_safe_halt+0x2/0x10 Code: f3 c3 65 48 8b 04 25 40 4c 01 00 f0 80 48 02 20 48 8b 00 a8 08 74 8b eb c1 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 fb f4 <c3> 0f 1f 00 66 2e 0f 1f 84 00 00 00 00 00 f4 c3 90 90 90 90 90 90 RSP: 0018:ffffc90000073ec8 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffdc RAX: 0000000000000001 RBX: 0000000000000001 RCX: ffff88007db19200 RDX: ffffffff81c30638 RSI: ffff88007db19200 RDI: 0000000000000087 RBP: ffffffff81c670e8 R08: 000001b3fa8aad88 R09: ffff88007c417c00 R10: 000000010000ecef R11: 000000000000a000 R12: 0000000000000000 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 default_idle+0xc/0x20 do_idle+0x1f0/0x220 ? do_idle+0x172/0x220 cpu_startup_entry+0x6a/0x70 secondary_startup_64+0xa4/0xb0 ---[ end trace a4bf7eecae5cc0ae ]--- RIP: 0010rb_insert_color+0x17/0x190 Code: 4c 89 78 10 e9 72 ff ff ff 49 89 ef e9 27 ff ff ff 66 90 48 8b 17 48 85 d2 0f 84 4d 01 00 00 48 8b 02 a8 01 0f 85 6d 01 00 00 <48> 8b 48 08 49 89 c0 48 39 d1 74 53 48 85 c9 74 09 f6 01 01 0f 84 RSP: 0018:ffff88007db03a58 EFLAGS: 00010246 RAX: 930d659731af356e RBX: ffff88007db03b3c RCX: ffff88005f09c8c0 RDX: ffff8800631c4c00 RSI: ffff88007c4474b0 RDI: ffff88005f09c8a0 RBP: 0000000000000001 R08: ffff8800631c4c00 R09: ffff88005f09c8d0 R10: ffff88007db03bc8 R11: 0000000000000000 R12: ffff88007c4474b0 R13: 0000000000000002 R14: ffff88005f09c8a0 R15: ffff8800631c4c00 FS: 0000000000000000(0000) GS:ffff88007db00000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f83d0291018 CR3: 000000007b036000 CR4: 00000000000406a0 Kernel panic - not syncing: Fatal exception in interrupt That's all I can get from machine's display. The following commits have touched nf_conncount/connlimit code: - 33b78aaa4457ce5d531c6a06f461f8d402774cad netfilter: use PTR_ERR_OR_ZERO() - 5c789e131cbb997a528451564ea4613e812fc718 netfilter: nf_conncount: Add list lock and gc worker, and RCU for init tree search - 34848d5c896ea1ab4e3c441b9c4fed39928ccbaf netfilter: nf_conncount: Split insert and traversal - 2ba39118c10ae3a7d3411c073485bba9576684cd netfilter: nf_conncount: Move locking into count_tree() - 976afca1ceba53df6f4a543014e15d1c7a962571 netfilter: nf_conncount: Early exit in nf_conncount_lookup() and cleanup - cb2b36f5a97df76f547fcc4ab444a02522fb6c96 netfilter: nf_conncount: Switch to plain list - 2a406e8ac7c3e7e96b94d6c0765d5a4641970446 netfilter: nf_conncount: Early exit for garbage collection - 5cd3da4ba2397ef07226ca2aa5094ed21ff8198f Merge ra.kernel.org:/pub/scm/linux/kernel/git/davem/net It looks like those locking related changes may be the cause. Bisecting it will be hard as I don't have exact packet stream triggering the issue and as a production system it's not ideal to run loops of testing. (note, system is running under QEMU at a hosting provider) Regards, Bruno