linux-stable.git/include/net/tcp.h, branch linux-5.4.y Linux kernel stable tree tcp: check skb is non-NULL in tcp_rto_delta_us() 2024-11-08T15:20:33+00:00 Josh Hunt johunt@akamai.com 2024-09-10T19:08:22+00:00 16e0387d87fc858e34449fdf2b14ed5837f761db [ Upstream commit c8770db2d54437a5f49417ae7b46f7de23d14db6 ] We have some machines running stock Ubuntu 20.04.6 which is their 5.4.0-174-generic kernel that are running ceph and recently hit a null ptr dereference in tcp_rearm_rto(). Initially hitting it from the TLP path, but then later we also saw it getting hit from the RACK case as well. Here are examples of the oops messages we saw in each of those cases: Jul 26 15:05:02 rx [11061395.780353] BUG: kernel NULL pointer dereference, address: 0000000000000020 Jul 26 15:05:02 rx [11061395.787572] #PF: supervisor read access in kernel mode Jul 26 15:05:02 rx [11061395.792971] #PF: error_code(0x0000) - not-present page Jul 26 15:05:02 rx [11061395.798362] PGD 0 P4D 0 Jul 26 15:05:02 rx [11061395.801164] Oops: 0000 [#1] SMP NOPTI Jul 26 15:05:02 rx [11061395.805091] CPU: 0 PID: 9180 Comm: msgr-worker-1 Tainted: G W 5.4.0-174-generic #193-Ubuntu Jul 26 15:05:02 rx [11061395.814996] Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023 Jul 26 15:05:02 rx [11061395.825952] RIP: 0010:tcp_rearm_rto+0xe4/0x160 Jul 26 15:05:02 rx [11061395.830656] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3 Jul 26 15:05:02 rx [11061395.849665] RSP: 0018:ffffb75d40003e08 EFLAGS: 00010246 Jul 26 15:05:02 rx [11061395.855149] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000 Jul 26 15:05:02 rx [11061395.862542] RDX: 0000000062177c30 RSI: 000000000000231c RDI: ffff9874ad283a60 Jul 26 15:05:02 rx [11061395.869933] RBP: ffffb75d40003e20 R08: 0000000000000000 R09: ffff987605e20aa8 Jul 26 15:05:02 rx [11061395.877318] R10: ffffb75d40003f00 R11: ffffb75d4460f740 R12: ffff9874ad283900 Jul 26 15:05:02 rx [11061395.884710] R13: ffff9874ad283a60 R14: ffff9874ad283980 R15: ffff9874ad283d30 Jul 26 15:05:02 rx [11061395.892095] FS: 00007f1ef4a2e700(0000) GS:ffff987605e00000(0000) knlGS:0000000000000000 Jul 26 15:05:02 rx [11061395.900438] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jul 26 15:05:02 rx [11061395.906435] CR2: 0000000000000020 CR3: 0000003e450ba003 CR4: 0000000000760ef0 Jul 26 15:05:02 rx [11061395.913822] PKRU: 55555554 Jul 26 15:05:02 rx [11061395.916786] Call Trace: Jul 26 15:05:02 rx [11061395.919488] Jul 26 15:05:02 rx [11061395.921765] ? show_regs.cold+0x1a/0x1f Jul 26 15:05:02 rx [11061395.925859] ? __die+0x90/0xd9 Jul 26 15:05:02 rx [11061395.929169] ? no_context+0x196/0x380 Jul 26 15:05:02 rx [11061395.933088] ? ip6_protocol_deliver_rcu+0x4e0/0x4e0 Jul 26 15:05:02 rx [11061395.938216] ? ip6_sublist_rcv_finish+0x3d/0x50 Jul 26 15:05:02 rx [11061395.943000] ? __bad_area_nosemaphore+0x50/0x1a0 Jul 26 15:05:02 rx [11061395.947873] ? bad_area_nosemaphore+0x16/0x20 Jul 26 15:05:02 rx [11061395.952486] ? do_user_addr_fault+0x267/0x450 Jul 26 15:05:02 rx [11061395.957104] ? ipv6_list_rcv+0x112/0x140 Jul 26 15:05:02 rx [11061395.961279] ? __do_page_fault+0x58/0x90 Jul 26 15:05:02 rx [11061395.965458] ? do_page_fault+0x2c/0xe0 Jul 26 15:05:02 rx [11061395.969465] ? page_fault+0x34/0x40 Jul 26 15:05:02 rx [11061395.973217] ? tcp_rearm_rto+0xe4/0x160 Jul 26 15:05:02 rx [11061395.977313] ? tcp_rearm_rto+0xe4/0x160 Jul 26 15:05:02 rx [11061395.981408] tcp_send_loss_probe+0x10b/0x220 Jul 26 15:05:02 rx [11061395.985937] tcp_write_timer_handler+0x1b4/0x240 Jul 26 15:05:02 rx [11061395.990809] tcp_write_timer+0x9e/0xe0 Jul 26 15:05:02 rx [11061395.994814] ? tcp_write_timer_handler+0x240/0x240 Jul 26 15:05:02 rx [11061395.999866] call_timer_fn+0x32/0x130 Jul 26 15:05:02 rx [11061396.003782] __run_timers.part.0+0x180/0x280 Jul 26 15:05:02 rx [11061396.008309] ? recalibrate_cpu_khz+0x10/0x10 Jul 26 15:05:02 rx [11061396.012841] ? native_x2apic_icr_write+0x30/0x30 Jul 26 15:05:02 rx [11061396.017718] ? lapic_next_event+0x21/0x30 Jul 26 15:05:02 rx [11061396.021984] ? clockevents_program_event+0x8f/0xe0 Jul 26 15:05:02 rx [11061396.027035] run_timer_softirq+0x2a/0x50 Jul 26 15:05:02 rx [11061396.031212] __do_softirq+0xd1/0x2c1 Jul 26 15:05:02 rx [11061396.035044] do_softirq_own_stack+0x2a/0x40 Jul 26 15:05:02 rx [11061396.039480] Jul 26 15:05:02 rx [11061396.041840] do_softirq.part.0+0x46/0x50 Jul 26 15:05:02 rx [11061396.046022] __local_bh_enable_ip+0x50/0x60 Jul 26 15:05:02 rx [11061396.050460] _raw_spin_unlock_bh+0x1e/0x20 Jul 26 15:05:02 rx [11061396.054817] nf_conntrack_tcp_packet+0x29e/0xbe0 [nf_conntrack] Jul 26 15:05:02 rx [11061396.060994] ? get_l4proto+0xe7/0x190 [nf_conntrack] Jul 26 15:05:02 rx [11061396.066220] nf_conntrack_in+0xe9/0x670 [nf_conntrack] Jul 26 15:05:02 rx [11061396.071618] ipv6_conntrack_local+0x14/0x20 [nf_conntrack] Jul 26 15:05:02 rx [11061396.077356] nf_hook_slow+0x45/0xb0 Jul 26 15:05:02 rx [11061396.081098] ip6_xmit+0x3f0/0x5d0 Jul 26 15:05:02 rx [11061396.084670] ? ipv6_anycast_cleanup+0x50/0x50 Jul 26 15:05:02 rx [11061396.089282] ? __sk_dst_check+0x38/0x70 Jul 26 15:05:02 rx [11061396.093381] ? inet6_csk_route_socket+0x13b/0x200 Jul 26 15:05:02 rx [11061396.098346] inet6_csk_xmit+0xa7/0xf0 Jul 26 15:05:02 rx [11061396.102263] __tcp_transmit_skb+0x550/0xb30 Jul 26 15:05:02 rx [11061396.106701] tcp_write_xmit+0x3c6/0xc20 Jul 26 15:05:02 rx [11061396.110792] ? __alloc_skb+0x98/0x1d0 Jul 26 15:05:02 rx [11061396.114708] __tcp_push_pending_frames+0x37/0x100 Jul 26 15:05:02 rx [11061396.119667] tcp_push+0xfd/0x100 Jul 26 15:05:02 rx [11061396.123150] tcp_sendmsg_locked+0xc70/0xdd0 Jul 26 15:05:02 rx [11061396.127588] tcp_sendmsg+0x2d/0x50 Jul 26 15:05:02 rx [11061396.131245] inet6_sendmsg+0x43/0x70 Jul 26 15:05:02 rx [11061396.135075] __sock_sendmsg+0x48/0x70 Jul 26 15:05:02 rx [11061396.138994] ____sys_sendmsg+0x212/0x280 Jul 26 15:05:02 rx [11061396.143172] ___sys_sendmsg+0x88/0xd0 Jul 26 15:05:02 rx [11061396.147098] ? __seccomp_filter+0x7e/0x6b0 Jul 26 15:05:02 rx [11061396.151446] ? __switch_to+0x39c/0x460 Jul 26 15:05:02 rx [11061396.155453] ? __switch_to_asm+0x42/0x80 Jul 26 15:05:02 rx [11061396.159636] ? __switch_to_asm+0x5a/0x80 Jul 26 15:05:02 rx [11061396.163816] __sys_sendmsg+0x5c/0xa0 Jul 26 15:05:02 rx [11061396.167647] __x64_sys_sendmsg+0x1f/0x30 Jul 26 15:05:02 rx [11061396.171832] do_syscall_64+0x57/0x190 Jul 26 15:05:02 rx [11061396.175748] entry_SYSCALL_64_after_hwframe+0x5c/0xc1 Jul 26 15:05:02 rx [11061396.181055] RIP: 0033:0x7f1ef692618d Jul 26 15:05:02 rx [11061396.184893] Code: 28 89 54 24 1c 48 89 74 24 10 89 7c 24 08 e8 ca ee ff ff 8b 54 24 1c 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 2f 44 89 c7 48 89 44 24 08 e8 fe ee ff ff 48 Jul 26 15:05:02 rx [11061396.203889] RSP: 002b:00007f1ef4a26aa0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e Jul 26 15:05:02 rx [11061396.211708] RAX: ffffffffffffffda RBX: 000000000000084b RCX: 00007f1ef692618d Jul 26 15:05:02 rx [11061396.219091] RDX: 0000000000004000 RSI: 00007f1ef4a26b10 RDI: 0000000000000275 Jul 26 15:05:02 rx [11061396.226475] RBP: 0000000000004000 R08: 0000000000000000 R09: 0000000000000020 Jul 26 15:05:02 rx [11061396.233859] R10: 0000000000000000 R11: 0000000000000293 R12: 000000000000084b Jul 26 15:05:02 rx [11061396.241243] R13: 00007f1ef4a26b10 R14: 0000000000000275 R15: 000055592030f1e8 Jul 26 15:05:02 rx [11061396.248628] Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif input_leds joydev rndis_host cdc_ether usbnet mii ast drm_vram_helper ttm drm_kms_helper i2c_algo_bit fb_sys_fops syscopyarea sysfillrect sysimgblt ccp mac_hid ipmi_si ipmi_devintf ipmi_msghandler nft_ct sch_fq_codel nf_tables_set nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink ramoops reed_solomon efi_pstore drm ip_tables x_tables autofs4 raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid0 multipath linear mlx5_ib ib_uverbs ib_core raid1 mlx5_core hid_generic pci_hyperv_intf crc32_pclmul tls usbhid ahci mlxfw bnxt_en libahci hid nvme i2c_piix4 nvme_core wmi Jul 26 15:05:02 rx [11061396.324334] CR2: 0000000000000020 Jul 26 15:05:02 rx [11061396.327944] ---[ end trace 68a2b679d1cfb4f1 ]--- Jul 26 15:05:02 rx [11061396.433435] RIP: 0010:tcp_rearm_rto+0xe4/0x160 Jul 26 15:05:02 rx [11061396.438137] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3 Jul 26 15:05:02 rx [11061396.457144] RSP: 0018:ffffb75d40003e08 EFLAGS: 00010246 Jul 26 15:05:02 rx [11061396.462629] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000 Jul 26 15:05:02 rx [11061396.470012] RDX: 0000000062177c30 RSI: 000000000000231c RDI: ffff9874ad283a60 Jul 26 15:05:02 rx [11061396.477396] RBP: ffffb75d40003e20 R08: 0000000000000000 R09: ffff987605e20aa8 Jul 26 15:05:02 rx [11061396.484779] R10: ffffb75d40003f00 R11: ffffb75d4460f740 R12: ffff9874ad283900 Jul 26 15:05:02 rx [11061396.492164] R13: ffff9874ad283a60 R14: ffff9874ad283980 R15: ffff9874ad283d30 Jul 26 15:05:02 rx [11061396.499547] FS: 00007f1ef4a2e700(0000) GS:ffff987605e00000(0000) knlGS:0000000000000000 Jul 26 15:05:02 rx [11061396.507886] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jul 26 15:05:02 rx [11061396.513884] CR2: 0000000000000020 CR3: 0000003e450ba003 CR4: 0000000000760ef0 Jul 26 15:05:02 rx [11061396.521267] PKRU: 55555554 Jul 26 15:05:02 rx [11061396.524230] Kernel panic - not syncing: Fatal exception in interrupt Jul 26 15:05:02 rx [11061396.530885] Kernel Offset: 0x1b200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff) Jul 26 15:05:03 rx [11061396.660181] ---[ end Kernel panic - not syncing: Fatal exception in interrupt ]--- After we hit this we disabled TLP by setting tcp_early_retrans to 0 and then hit the crash in the RACK case: Aug 7 07:26:16 rx [1006006.265582] BUG: kernel NULL pointer dereference, address: 0000000000000020 Aug 7 07:26:16 rx [1006006.272719] #PF: supervisor read access in kernel mode Aug 7 07:26:16 rx [1006006.278030] #PF: error_code(0x0000) - not-present page Aug 7 07:26:16 rx [1006006.283343] PGD 0 P4D 0 Aug 7 07:26:16 rx [1006006.286057] Oops: 0000 [#1] SMP NOPTI Aug 7 07:26:16 rx [1006006.289896] CPU: 5 PID: 0 Comm: swapper/5 Tainted: G W 5.4.0-174-generic #193-Ubuntu Aug 7 07:26:16 rx [1006006.299107] Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023 Aug 7 07:26:16 rx [1006006.309970] RIP: 0010:tcp_rearm_rto+0xe4/0x160 Aug 7 07:26:16 rx [1006006.314584] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3 Aug 7 07:26:16 rx [1006006.333499] RSP: 0018:ffffb42600a50960 EFLAGS: 00010246 Aug 7 07:26:16 rx [1006006.338895] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000 Aug 7 07:26:16 rx [1006006.346193] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff92d687ed8160 Aug 7 07:26:16 rx [1006006.353489] RBP: ffffb42600a50978 R08: 0000000000000000 R09: 00000000cd896dcc Aug 7 07:26:16 rx [1006006.360786] R10: ffff92dc3404f400 R11: 0000000000000001 R12: ffff92d687ed8000 Aug 7 07:26:16 rx [1006006.368084] R13: ffff92d687ed8160 R14: 00000000cd896dcc R15: 00000000cd8fca81 Aug 7 07:26:16 rx [1006006.375381] FS: 0000000000000000(0000) GS:ffff93158ad40000(0000) knlGS:0000000000000000 Aug 7 07:26:16 rx [1006006.383632] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Aug 7 07:26:16 rx [1006006.389544] CR2: 0000000000000020 CR3: 0000003e775ce006 CR4: 0000000000760ee0 Aug 7 07:26:16 rx [1006006.396839] PKRU: 55555554 Aug 7 07:26:16 rx [1006006.399717] Call Trace: Aug 7 07:26:16 rx [1006006.402335] Aug 7 07:26:16 rx [1006006.404525] ? show_regs.cold+0x1a/0x1f Aug 7 07:26:16 rx [1006006.408532] ? __die+0x90/0xd9 Aug 7 07:26:16 rx [1006006.411760] ? no_context+0x196/0x380 Aug 7 07:26:16 rx [1006006.415599] ? __bad_area_nosemaphore+0x50/0x1a0 Aug 7 07:26:16 rx [1006006.420392] ? _raw_spin_lock+0x1e/0x30 Aug 7 07:26:16 rx [1006006.424401] ? bad_area_nosemaphore+0x16/0x20 Aug 7 07:26:16 rx [1006006.428927] ? do_user_addr_fault+0x267/0x450 Aug 7 07:26:16 rx [1006006.433450] ? __do_page_fault+0x58/0x90 Aug 7 07:26:16 rx [1006006.437542] ? do_page_fault+0x2c/0xe0 Aug 7 07:26:16 rx [1006006.441470] ? page_fault+0x34/0x40 Aug 7 07:26:16 rx [1006006.445134] ? tcp_rearm_rto+0xe4/0x160 Aug 7 07:26:16 rx [1006006.449145] tcp_ack+0xa32/0xb30 Aug 7 07:26:16 rx [1006006.452542] tcp_rcv_established+0x13c/0x670 Aug 7 07:26:16 rx [1006006.456981] ? sk_filter_trim_cap+0x48/0x220 Aug 7 07:26:16 rx [1006006.461419] tcp_v6_do_rcv+0xdb/0x450 Aug 7 07:26:16 rx [1006006.465257] tcp_v6_rcv+0xc2b/0xd10 Aug 7 07:26:16 rx [1006006.468918] ip6_protocol_deliver_rcu+0xd3/0x4e0 Aug 7 07:26:16 rx [1006006.473706] ip6_input_finish+0x15/0x20 Aug 7 07:26:16 rx [1006006.477710] ip6_input+0xa2/0xb0 Aug 7 07:26:16 rx [1006006.481109] ? ip6_protocol_deliver_rcu+0x4e0/0x4e0 Aug 7 07:26:16 rx [1006006.486151] ip6_sublist_rcv_finish+0x3d/0x50 Aug 7 07:26:16 rx [1006006.490679] ip6_sublist_rcv+0x1aa/0x250 Aug 7 07:26:16 rx [1006006.494779] ? ip6_rcv_finish_core.isra.0+0xa0/0xa0 Aug 7 07:26:16 rx [1006006.499828] ipv6_list_rcv+0x112/0x140 Aug 7 07:26:16 rx [1006006.503748] __netif_receive_skb_list_core+0x1a4/0x250 Aug 7 07:26:16 rx [1006006.509057] netif_receive_skb_list_internal+0x1a1/0x2b0 Aug 7 07:26:16 rx [1006006.514538] gro_normal_list.part.0+0x1e/0x40 Aug 7 07:26:16 rx [1006006.519068] napi_complete_done+0x91/0x130 Aug 7 07:26:16 rx [1006006.523352] mlx5e_napi_poll+0x18e/0x610 [mlx5_core] Aug 7 07:26:16 rx [1006006.528481] net_rx_action+0x142/0x390 Aug 7 07:26:16 rx [1006006.532398] __do_softirq+0xd1/0x2c1 Aug 7 07:26:16 rx [1006006.536142] irq_exit+0xae/0xb0 Aug 7 07:26:16 rx [1006006.539452] do_IRQ+0x5a/0xf0 Aug 7 07:26:16 rx [1006006.542590] common_interrupt+0xf/0xf Aug 7 07:26:16 rx [1006006.546421] Aug 7 07:26:16 rx [1006006.548695] RIP: 0010:native_safe_halt+0xe/0x10 Aug 7 07:26:16 rx [1006006.553399] Code: 7b ff ff ff eb bd 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 36 2c 50 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 26 2c 50 00 fb f4 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 e8 dd 5e 61 ff 65 Aug 7 07:26:16 rx [1006006.572309] RSP: 0018:ffffb42600177e70 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffc2 Aug 7 07:26:16 rx [1006006.580040] RAX: ffffffff8ed08b20 RBX: 0000000000000005 RCX: 0000000000000001 Aug 7 07:26:16 rx [1006006.587337] RDX: 00000000f48eeca2 RSI: 0000000000000082 RDI: 0000000000000082 Aug 7 07:26:16 rx [1006006.594635] RBP: ffffb42600177e90 R08: 0000000000000000 R09: 000000000000020f Aug 7 07:26:16 rx [1006006.601931] R10: 0000000000100000 R11: 0000000000000000 R12: 0000000000000005 Aug 7 07:26:16 rx [1006006.609229] R13: ffff93157deb5f00 R14: 0000000000000000 R15: 0000000000000000 Aug 7 07:26:16 rx [1006006.616530] ? __cpuidle_text_start+0x8/0x8 Aug 7 07:26:16 rx [1006006.620886] ? default_idle+0x20/0x140 Aug 7 07:26:16 rx [1006006.624804] arch_cpu_idle+0x15/0x20 Aug 7 07:26:16 rx [1006006.628545] default_idle_call+0x23/0x30 Aug 7 07:26:16 rx [1006006.632640] do_idle+0x1fb/0x270 Aug 7 07:26:16 rx [1006006.636035] cpu_startup_entry+0x20/0x30 Aug 7 07:26:16 rx [1006006.640126] start_secondary+0x178/0x1d0 Aug 7 07:26:16 rx [1006006.644218] secondary_startup_64+0xa4/0xb0 Aug 7 07:26:17 rx [1006006.648568] Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 nft_ct amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif input_leds joydev rndis_host cdc_ether usbnet ast mii drm_vram_helper ttm drm_kms_helper i2c_algo_bit fb_sys_fops syscopyarea sysfillrect sysimgblt ccp mac_hid ipmi_si ipmi_devintf ipmi_msghandler sch_fq_codel nf_tables_set nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink ramoops reed_solomon efi_pstore drm ip_tables x_tables autofs4 raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid0 multipath linear mlx5_ib ib_uverbs ib_core raid1 hid_generic mlx5_core pci_hyperv_intf crc32_pclmul usbhid ahci tls mlxfw bnxt_en hid libahci nvme i2c_piix4 nvme_core wmi [last unloaded: cpuid] Aug 7 07:26:17 rx [1006006.726180] CR2: 0000000000000020 Aug 7 07:26:17 rx [1006006.729718] ---[ end trace e0e2e37e4e612984 ]--- Prior to seeing the first crash and on other machines we also see the warning in tcp_send_loss_probe() where packets_out is non-zero, but both transmit and retrans queues are empty so we know the box is seeing some accounting issue in this area: Jul 26 09:15:27 kernel: ------------[ cut here ]------------ Jul 26 09:15:27 kernel: invalid inflight: 2 state 1 cwnd 68 mss 8988 Jul 26 09:15:27 kernel: WARNING: CPU: 16 PID: 0 at net/ipv4/tcp_output.c:2605 tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 nft_ct amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif joydev input_leds rndis_host cdc_ether usbnet mii ast drm_vram_helper ttm drm_kms_he> Jul 26 09:15:27 kernel: CPU: 16 PID: 0 Comm: swapper/16 Not tainted 5.4.0-174-generic #193-Ubuntu Jul 26 09:15:27 kernel: Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023 Jul 26 09:15:27 kernel: RIP: 0010:tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: Code: 08 26 01 00 75 e2 41 0f b6 54 24 12 41 8b 8c 24 c0 06 00 00 45 89 f0 48 c7 c7 e0 b4 20 a7 c6 05 8d 08 26 01 01 e8 4a c0 0f 00 <0f> 0b eb ba 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41 Jul 26 09:15:27 kernel: RSP: 0018:ffffb7838088ce00 EFLAGS: 00010286 Jul 26 09:15:27 kernel: RAX: 0000000000000000 RBX: ffff9b84b5630430 RCX: 0000000000000006 Jul 26 09:15:27 kernel: RDX: 0000000000000007 RSI: 0000000000000096 RDI: ffff9b8e4621c8c0 Jul 26 09:15:27 kernel: RBP: ffffb7838088ce18 R08: 0000000000000927 R09: 0000000000000004 Jul 26 09:15:27 kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff9b84b5630000 Jul 26 09:15:27 kernel: R13: 0000000000000000 R14: 000000000000231c R15: ffff9b84b5630430 Jul 26 09:15:27 kernel: FS: 0000000000000000(0000) GS:ffff9b8e46200000(0000) knlGS:0000000000000000 Jul 26 09:15:27 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 Jul 26 09:15:27 kernel: CR2: 000056238cec2380 CR3: 0000003e49ede005 CR4: 0000000000760ee0 Jul 26 09:15:27 kernel: PKRU: 55555554 Jul 26 09:15:27 kernel: Call Trace: Jul 26 09:15:27 kernel: <IRQ> Jul 26 09:15:27 kernel: ? show_regs.cold+0x1a/0x1f Jul 26 09:15:27 kernel: ? __warn+0x98/0xe0 Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: ? report_bug+0xd1/0x100 Jul 26 09:15:27 kernel: ? do_error_trap+0x9b/0xc0 Jul 26 09:15:27 kernel: ? do_invalid_op+0x3c/0x50 Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: ? invalid_op+0x1e/0x30 Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: tcp_write_timer_handler+0x1b4/0x240 Jul 26 09:15:27 kernel: tcp_write_timer+0x9e/0xe0 Jul 26 09:15:27 kernel: ? tcp_write_timer_handler+0x240/0x240 Jul 26 09:15:27 kernel: call_timer_fn+0x32/0x130 Jul 26 09:15:27 kernel: __run_timers.part.0+0x180/0x280 Jul 26 09:15:27 kernel: ? timerqueue_add+0x9b/0xb0 Jul 26 09:15:27 kernel: ? enqueue_hrtimer+0x3d/0x90 Jul 26 09:15:27 kernel: ? do_error_trap+0x9b/0xc0 Jul 26 09:15:27 kernel: ? do_invalid_op+0x3c/0x50 Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: ? invalid_op+0x1e/0x30 Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220 Jul 26 09:15:27 kernel: tcp_write_timer_handler+0x1b4/0x240 Jul 26 09:15:27 kernel: tcp_write_timer+0x9e/0xe0 Jul 26 09:15:27 kernel: ? tcp_write_timer_handler+0x240/0x240 Jul 26 09:15:27 kernel: call_timer_fn+0x32/0x130 Jul 26 09:15:27 kernel: __run_timers.part.0+0x180/0x280 Jul 26 09:15:27 kernel: ? timerqueue_add+0x9b/0xb0 Jul 26 09:15:27 kernel: ? enqueue_hrtimer+0x3d/0x90 Jul 26 09:15:27 kernel: ? recalibrate_cpu_khz+0x10/0x10 Jul 26 09:15:27 kernel: ? ktime_get+0x3e/0xa0 Jul 26 09:15:27 kernel: ? native_x2apic_icr_write+0x30/0x30 Jul 26 09:15:27 kernel: run_timer_softirq+0x2a/0x50 Jul 26 09:15:27 kernel: __do_softirq+0xd1/0x2c1 Jul 26 09:15:27 kernel: irq_exit+0xae/0xb0 Jul 26 09:15:27 kernel: smp_apic_timer_interrupt+0x7b/0x140 Jul 26 09:15:27 kernel: apic_timer_interrupt+0xf/0x20 Jul 26 09:15:27 kernel: </IRQ> Jul 26 09:15:27 kernel: RIP: 0010:native_safe_halt+0xe/0x10 Jul 26 09:15:27 kernel: Code: 7b ff ff ff eb bd 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 36 2c 50 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 26 2c 50 00 fb f4 <c3> 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 e8 dd 5e 61 ff 65 Jul 26 09:15:27 kernel: RSP: 0018:ffffb783801cfe70 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13 Jul 26 09:15:27 kernel: RAX: ffffffffa6908b20 RBX: 0000000000000010 RCX: 0000000000000001 Jul 26 09:15:27 kernel: RDX: 000000006fc0c97e RSI: 0000000000000082 RDI: 0000000000000082 Jul 26 09:15:27 kernel: RBP: ffffb783801cfe90 R08: 0000000000000000 R09: 0000000000000225 Jul 26 09:15:27 kernel: R10: 0000000000100000 R11: 0000000000000000 R12: 0000000000000010 Jul 26 09:15:27 kernel: R13: ffff9b8e390b0000 R14: 0000000000000000 R15: 0000000000000000 Jul 26 09:15:27 kernel: ? __cpuidle_text_start+0x8/0x8 Jul 26 09:15:27 kernel: ? default_idle+0x20/0x140 Jul 26 09:15:27 kernel: arch_cpu_idle+0x15/0x20 Jul 26 09:15:27 kernel: default_idle_call+0x23/0x30 Jul 26 09:15:27 kernel: do_idle+0x1fb/0x270 Jul 26 09:15:27 kernel: cpu_startup_entry+0x20/0x30 Jul 26 09:15:27 kernel: start_secondary+0x178/0x1d0 Jul 26 09:15:27 kernel: secondary_startup_64+0xa4/0xb0 Jul 26 09:15:27 kernel: ---[ end trace e7ac822987e33be1 ]--- The NULL ptr deref is coming from tcp_rto_delta_us() attempting to pull an skb off the head of the retransmit queue and then dereferencing that skb to get the skb_mstamp_ns value via tcp_skb_timestamp_us(skb). The crash is the same one that was reported a # of years ago here: https://lore.kernel.org/netdev/86c0f836-9a7c-438b-d81a-839be45f1f58@gmail.com/T/#t and the kernel we're running has the fix which was added to resolve this issue. Unfortunately we've been unsuccessful so far in reproducing this problem in the lab and do not have the luxury of pushing out a new kernel to try and test if newer kernels resolve this issue at the moment. I realize this is a report against both an Ubuntu kernel and also an older 5.4 kernel. I have reported this issue to Ubuntu here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2077657 however I feel like since this issue has possibly cropped up again it makes sense to build in some protection in this path (even on the latest kernel versions) since the code in question just blindly assumes there's a valid skb without testing if it's NULL b/f it looks at the timestamp. Given we have seen crashes in this path before and now this case it seems like we should protect ourselves for when packets_out accounting is incorrect. While we should fix that root cause we should also just make sure the skb is not NULL before dereferencing it. Also add a warn once here to capture some information if/when the problem case is hit again. Fixes: e1a10ef7fa87 ("tcp: introduce tcp_rto_delta_us() helper for xmit timer fix") Signed-off-by: Josh Hunt <johunt@akamai.com> Acked-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit c8770db2d54437a5f49417ae7b46f7de23d14db6 ]

We have some machines running stock Ubuntu 20.04.6 which is their 5.4.0-174-generic
kernel that are running ceph and recently hit a null ptr dereference in
tcp_rearm_rto(). Initially hitting it from the TLP path, but then later we also
saw it getting hit from the RACK case as well. Here are examples of the oops
messages we saw in each of those cases:

Jul 26 15:05:02 rx [11061395.780353] BUG: kernel NULL pointer dereference, address: 0000000000000020
Jul 26 15:05:02 rx [11061395.787572] #PF: supervisor read access in kernel mode
Jul 26 15:05:02 rx [11061395.792971] #PF: error_code(0x0000) - not-present page
Jul 26 15:05:02 rx [11061395.798362] PGD 0 P4D 0
Jul 26 15:05:02 rx [11061395.801164] Oops: 0000 [#1] SMP NOPTI
Jul 26 15:05:02 rx [11061395.805091] CPU: 0 PID: 9180 Comm: msgr-worker-1 Tainted: G W 5.4.0-174-generic #193-Ubuntu
Jul 26 15:05:02 rx [11061395.814996] Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023
Jul 26 15:05:02 rx [11061395.825952] RIP: 0010:tcp_rearm_rto+0xe4/0x160
Jul 26 15:05:02 rx [11061395.830656] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3
Jul 26 15:05:02 rx [11061395.849665] RSP: 0018:ffffb75d40003e08 EFLAGS: 00010246
Jul 26 15:05:02 rx [11061395.855149] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000
Jul 26 15:05:02 rx [11061395.862542] RDX: 0000000062177c30 RSI: 000000000000231c RDI: ffff9874ad283a60
Jul 26 15:05:02 rx [11061395.869933] RBP: ffffb75d40003e20 R08: 0000000000000000 R09: ffff987605e20aa8
Jul 26 15:05:02 rx [11061395.877318] R10: ffffb75d40003f00 R11: ffffb75d4460f740 R12: ffff9874ad283900
Jul 26 15:05:02 rx [11061395.884710] R13: ffff9874ad283a60 R14: ffff9874ad283980 R15: ffff9874ad283d30
Jul 26 15:05:02 rx [11061395.892095] FS: 00007f1ef4a2e700(0000) GS:ffff987605e00000(0000) knlGS:0000000000000000
Jul 26 15:05:02 rx [11061395.900438] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 26 15:05:02 rx [11061395.906435] CR2: 0000000000000020 CR3: 0000003e450ba003 CR4: 0000000000760ef0
Jul 26 15:05:02 rx [11061395.913822] PKRU: 55555554
Jul 26 15:05:02 rx [11061395.916786] Call Trace:
Jul 26 15:05:02 rx [11061395.919488]
Jul 26 15:05:02 rx [11061395.921765] ? show_regs.cold+0x1a/0x1f
Jul 26 15:05:02 rx [11061395.925859] ? __die+0x90/0xd9
Jul 26 15:05:02 rx [11061395.929169] ? no_context+0x196/0x380
Jul 26 15:05:02 rx [11061395.933088] ? ip6_protocol_deliver_rcu+0x4e0/0x4e0
Jul 26 15:05:02 rx [11061395.938216] ? ip6_sublist_rcv_finish+0x3d/0x50
Jul 26 15:05:02 rx [11061395.943000] ? __bad_area_nosemaphore+0x50/0x1a0
Jul 26 15:05:02 rx [11061395.947873] ? bad_area_nosemaphore+0x16/0x20
Jul 26 15:05:02 rx [11061395.952486] ? do_user_addr_fault+0x267/0x450
Jul 26 15:05:02 rx [11061395.957104] ? ipv6_list_rcv+0x112/0x140
Jul 26 15:05:02 rx [11061395.961279] ? __do_page_fault+0x58/0x90
Jul 26 15:05:02 rx [11061395.965458] ? do_page_fault+0x2c/0xe0
Jul 26 15:05:02 rx [11061395.969465] ? page_fault+0x34/0x40
Jul 26 15:05:02 rx [11061395.973217] ? tcp_rearm_rto+0xe4/0x160
Jul 26 15:05:02 rx [11061395.977313] ? tcp_rearm_rto+0xe4/0x160
Jul 26 15:05:02 rx [11061395.981408] tcp_send_loss_probe+0x10b/0x220
Jul 26 15:05:02 rx [11061395.985937] tcp_write_timer_handler+0x1b4/0x240
Jul 26 15:05:02 rx [11061395.990809] tcp_write_timer+0x9e/0xe0
Jul 26 15:05:02 rx [11061395.994814] ? tcp_write_timer_handler+0x240/0x240
Jul 26 15:05:02 rx [11061395.999866] call_timer_fn+0x32/0x130
Jul 26 15:05:02 rx [11061396.003782] __run_timers.part.0+0x180/0x280
Jul 26 15:05:02 rx [11061396.008309] ? recalibrate_cpu_khz+0x10/0x10
Jul 26 15:05:02 rx [11061396.012841] ? native_x2apic_icr_write+0x30/0x30
Jul 26 15:05:02 rx [11061396.017718] ? lapic_next_event+0x21/0x30
Jul 26 15:05:02 rx [11061396.021984] ? clockevents_program_event+0x8f/0xe0
Jul 26 15:05:02 rx [11061396.027035] run_timer_softirq+0x2a/0x50
Jul 26 15:05:02 rx [11061396.031212] __do_softirq+0xd1/0x2c1
Jul 26 15:05:02 rx [11061396.035044] do_softirq_own_stack+0x2a/0x40
Jul 26 15:05:02 rx [11061396.039480]
Jul 26 15:05:02 rx [11061396.041840] do_softirq.part.0+0x46/0x50
Jul 26 15:05:02 rx [11061396.046022] __local_bh_enable_ip+0x50/0x60
Jul 26 15:05:02 rx [11061396.050460] _raw_spin_unlock_bh+0x1e/0x20
Jul 26 15:05:02 rx [11061396.054817] nf_conntrack_tcp_packet+0x29e/0xbe0 [nf_conntrack]
Jul 26 15:05:02 rx [11061396.060994] ? get_l4proto+0xe7/0x190 [nf_conntrack]
Jul 26 15:05:02 rx [11061396.066220] nf_conntrack_in+0xe9/0x670 [nf_conntrack]
Jul 26 15:05:02 rx [11061396.071618] ipv6_conntrack_local+0x14/0x20 [nf_conntrack]
Jul 26 15:05:02 rx [11061396.077356] nf_hook_slow+0x45/0xb0
Jul 26 15:05:02 rx [11061396.081098] ip6_xmit+0x3f0/0x5d0
Jul 26 15:05:02 rx [11061396.084670] ? ipv6_anycast_cleanup+0x50/0x50
Jul 26 15:05:02 rx [11061396.089282] ? __sk_dst_check+0x38/0x70
Jul 26 15:05:02 rx [11061396.093381] ? inet6_csk_route_socket+0x13b/0x200
Jul 26 15:05:02 rx [11061396.098346] inet6_csk_xmit+0xa7/0xf0
Jul 26 15:05:02 rx [11061396.102263] __tcp_transmit_skb+0x550/0xb30
Jul 26 15:05:02 rx [11061396.106701] tcp_write_xmit+0x3c6/0xc20
Jul 26 15:05:02 rx [11061396.110792] ? __alloc_skb+0x98/0x1d0
Jul 26 15:05:02 rx [11061396.114708] __tcp_push_pending_frames+0x37/0x100
Jul 26 15:05:02 rx [11061396.119667] tcp_push+0xfd/0x100
Jul 26 15:05:02 rx [11061396.123150] tcp_sendmsg_locked+0xc70/0xdd0
Jul 26 15:05:02 rx [11061396.127588] tcp_sendmsg+0x2d/0x50
Jul 26 15:05:02 rx [11061396.131245] inet6_sendmsg+0x43/0x70
Jul 26 15:05:02 rx [11061396.135075] __sock_sendmsg+0x48/0x70
Jul 26 15:05:02 rx [11061396.138994] ____sys_sendmsg+0x212/0x280
Jul 26 15:05:02 rx [11061396.143172] ___sys_sendmsg+0x88/0xd0
Jul 26 15:05:02 rx [11061396.147098] ? __seccomp_filter+0x7e/0x6b0
Jul 26 15:05:02 rx [11061396.151446] ? __switch_to+0x39c/0x460
Jul 26 15:05:02 rx [11061396.155453] ? __switch_to_asm+0x42/0x80
Jul 26 15:05:02 rx [11061396.159636] ? __switch_to_asm+0x5a/0x80
Jul 26 15:05:02 rx [11061396.163816] __sys_sendmsg+0x5c/0xa0
Jul 26 15:05:02 rx [11061396.167647] __x64_sys_sendmsg+0x1f/0x30
Jul 26 15:05:02 rx [11061396.171832] do_syscall_64+0x57/0x190
Jul 26 15:05:02 rx [11061396.175748] entry_SYSCALL_64_after_hwframe+0x5c/0xc1
Jul 26 15:05:02 rx [11061396.181055] RIP: 0033:0x7f1ef692618d
Jul 26 15:05:02 rx [11061396.184893] Code: 28 89 54 24 1c 48 89 74 24 10 89 7c 24 08 e8 ca ee ff ff 8b 54 24 1c 48 8b 74 24 10 41 89 c0 8b 7c 24 08 b8 2e 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 2f 44 89 c7 48 89 44 24 08 e8 fe ee ff ff 48
Jul 26 15:05:02 rx [11061396.203889] RSP: 002b:00007f1ef4a26aa0 EFLAGS: 00000293 ORIG_RAX: 000000000000002e
Jul 26 15:05:02 rx [11061396.211708] RAX: ffffffffffffffda RBX: 000000000000084b RCX: 00007f1ef692618d
Jul 26 15:05:02 rx [11061396.219091] RDX: 0000000000004000 RSI: 00007f1ef4a26b10 RDI: 0000000000000275
Jul 26 15:05:02 rx [11061396.226475] RBP: 0000000000004000 R08: 0000000000000000 R09: 0000000000000020
Jul 26 15:05:02 rx [11061396.233859] R10: 0000000000000000 R11: 0000000000000293 R12: 000000000000084b
Jul 26 15:05:02 rx [11061396.241243] R13: 00007f1ef4a26b10 R14: 0000000000000275 R15: 000055592030f1e8
Jul 26 15:05:02 rx [11061396.248628] Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif input_leds joydev rndis_host cdc_ether usbnet mii ast drm_vram_helper ttm drm_kms_helper i2c_algo_bit fb_sys_fops syscopyarea sysfillrect sysimgblt ccp mac_hid ipmi_si ipmi_devintf ipmi_msghandler nft_ct sch_fq_codel nf_tables_set nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink ramoops reed_solomon efi_pstore drm ip_tables x_tables autofs4 raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid0 multipath linear mlx5_ib ib_uverbs ib_core raid1 mlx5_core hid_generic pci_hyperv_intf crc32_pclmul tls usbhid ahci mlxfw bnxt_en libahci hid nvme i2c_piix4 nvme_core wmi
Jul 26 15:05:02 rx [11061396.324334] CR2: 0000000000000020
Jul 26 15:05:02 rx [11061396.327944] ---[ end trace 68a2b679d1cfb4f1 ]---
Jul 26 15:05:02 rx [11061396.433435] RIP: 0010:tcp_rearm_rto+0xe4/0x160
Jul 26 15:05:02 rx [11061396.438137] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3
Jul 26 15:05:02 rx [11061396.457144] RSP: 0018:ffffb75d40003e08 EFLAGS: 00010246
Jul 26 15:05:02 rx [11061396.462629] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000
Jul 26 15:05:02 rx [11061396.470012] RDX: 0000000062177c30 RSI: 000000000000231c RDI: ffff9874ad283a60
Jul 26 15:05:02 rx [11061396.477396] RBP: ffffb75d40003e20 R08: 0000000000000000 R09: ffff987605e20aa8
Jul 26 15:05:02 rx [11061396.484779] R10: ffffb75d40003f00 R11: ffffb75d4460f740 R12: ffff9874ad283900
Jul 26 15:05:02 rx [11061396.492164] R13: ffff9874ad283a60 R14: ffff9874ad283980 R15: ffff9874ad283d30
Jul 26 15:05:02 rx [11061396.499547] FS: 00007f1ef4a2e700(0000) GS:ffff987605e00000(0000) knlGS:0000000000000000
Jul 26 15:05:02 rx [11061396.507886] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 26 15:05:02 rx [11061396.513884] CR2: 0000000000000020 CR3: 0000003e450ba003 CR4: 0000000000760ef0
Jul 26 15:05:02 rx [11061396.521267] PKRU: 55555554
Jul 26 15:05:02 rx [11061396.524230] Kernel panic - not syncing: Fatal exception in interrupt
Jul 26 15:05:02 rx [11061396.530885] Kernel Offset: 0x1b200000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbfffffff)
Jul 26 15:05:03 rx [11061396.660181] ---[ end Kernel panic - not syncing: Fatal
 exception in interrupt ]---

After we hit this we disabled TLP by setting tcp_early_retrans to 0 and then hit the crash in the RACK case:

Aug 7 07:26:16 rx [1006006.265582] BUG: kernel NULL pointer dereference, address: 0000000000000020
Aug 7 07:26:16 rx [1006006.272719] #PF: supervisor read access in kernel mode
Aug 7 07:26:16 rx [1006006.278030] #PF: error_code(0x0000) - not-present page
Aug 7 07:26:16 rx [1006006.283343] PGD 0 P4D 0
Aug 7 07:26:16 rx [1006006.286057] Oops: 0000 [#1] SMP NOPTI
Aug 7 07:26:16 rx [1006006.289896] CPU: 5 PID: 0 Comm: swapper/5 Tainted: G W 5.4.0-174-generic #193-Ubuntu
Aug 7 07:26:16 rx [1006006.299107] Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023
Aug 7 07:26:16 rx [1006006.309970] RIP: 0010:tcp_rearm_rto+0xe4/0x160
Aug 7 07:26:16 rx [1006006.314584] Code: 87 ca 04 00 00 00 5b 41 5c 41 5d 5d c3 c3 49 8b bc 24 40 06 00 00 eb 8d 48 bb cf f7 53 e3 a5 9b c4 20 4c 89 ef e8 0c fe 0e 00 <48> 8b 78 20 48 c1 ef 03 48 89 f8 41 8b bc 24 80 04 00 00 48 f7 e3
Aug 7 07:26:16 rx [1006006.333499] RSP: 0018:ffffb42600a50960 EFLAGS: 00010246
Aug 7 07:26:16 rx [1006006.338895] RAX: 0000000000000000 RBX: 20c49ba5e353f7cf RCX: 0000000000000000
Aug 7 07:26:16 rx [1006006.346193] RDX: 0000000000000000 RSI: 0000000000000001 RDI: ffff92d687ed8160
Aug 7 07:26:16 rx [1006006.353489] RBP: ffffb42600a50978 R08: 0000000000000000 R09: 00000000cd896dcc
Aug 7 07:26:16 rx [1006006.360786] R10: ffff92dc3404f400 R11: 0000000000000001 R12: ffff92d687ed8000
Aug 7 07:26:16 rx [1006006.368084] R13: ffff92d687ed8160 R14: 00000000cd896dcc R15: 00000000cd8fca81
Aug 7 07:26:16 rx [1006006.375381] FS: 0000000000000000(0000) GS:ffff93158ad40000(0000) knlGS:0000000000000000
Aug 7 07:26:16 rx [1006006.383632] CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Aug 7 07:26:16 rx [1006006.389544] CR2: 0000000000000020 CR3: 0000003e775ce006 CR4: 0000000000760ee0
Aug 7 07:26:16 rx [1006006.396839] PKRU: 55555554
Aug 7 07:26:16 rx [1006006.399717] Call Trace:
Aug 7 07:26:16 rx [1006006.402335]
Aug 7 07:26:16 rx [1006006.404525] ? show_regs.cold+0x1a/0x1f
Aug 7 07:26:16 rx [1006006.408532] ? __die+0x90/0xd9
Aug 7 07:26:16 rx [1006006.411760] ? no_context+0x196/0x380
Aug 7 07:26:16 rx [1006006.415599] ? __bad_area_nosemaphore+0x50/0x1a0
Aug 7 07:26:16 rx [1006006.420392] ? _raw_spin_lock+0x1e/0x30
Aug 7 07:26:16 rx [1006006.424401] ? bad_area_nosemaphore+0x16/0x20
Aug 7 07:26:16 rx [1006006.428927] ? do_user_addr_fault+0x267/0x450
Aug 7 07:26:16 rx [1006006.433450] ? __do_page_fault+0x58/0x90
Aug 7 07:26:16 rx [1006006.437542] ? do_page_fault+0x2c/0xe0
Aug 7 07:26:16 rx [1006006.441470] ? page_fault+0x34/0x40
Aug 7 07:26:16 rx [1006006.445134] ? tcp_rearm_rto+0xe4/0x160
Aug 7 07:26:16 rx [1006006.449145] tcp_ack+0xa32/0xb30
Aug 7 07:26:16 rx [1006006.452542] tcp_rcv_established+0x13c/0x670
Aug 7 07:26:16 rx [1006006.456981] ? sk_filter_trim_cap+0x48/0x220
Aug 7 07:26:16 rx [1006006.461419] tcp_v6_do_rcv+0xdb/0x450
Aug 7 07:26:16 rx [1006006.465257] tcp_v6_rcv+0xc2b/0xd10
Aug 7 07:26:16 rx [1006006.468918] ip6_protocol_deliver_rcu+0xd3/0x4e0
Aug 7 07:26:16 rx [1006006.473706] ip6_input_finish+0x15/0x20
Aug 7 07:26:16 rx [1006006.477710] ip6_input+0xa2/0xb0
Aug 7 07:26:16 rx [1006006.481109] ? ip6_protocol_deliver_rcu+0x4e0/0x4e0
Aug 7 07:26:16 rx [1006006.486151] ip6_sublist_rcv_finish+0x3d/0x50
Aug 7 07:26:16 rx [1006006.490679] ip6_sublist_rcv+0x1aa/0x250
Aug 7 07:26:16 rx [1006006.494779] ? ip6_rcv_finish_core.isra.0+0xa0/0xa0
Aug 7 07:26:16 rx [1006006.499828] ipv6_list_rcv+0x112/0x140
Aug 7 07:26:16 rx [1006006.503748] __netif_receive_skb_list_core+0x1a4/0x250
Aug 7 07:26:16 rx [1006006.509057] netif_receive_skb_list_internal+0x1a1/0x2b0
Aug 7 07:26:16 rx [1006006.514538] gro_normal_list.part.0+0x1e/0x40
Aug 7 07:26:16 rx [1006006.519068] napi_complete_done+0x91/0x130
Aug 7 07:26:16 rx [1006006.523352] mlx5e_napi_poll+0x18e/0x610 [mlx5_core]
Aug 7 07:26:16 rx [1006006.528481] net_rx_action+0x142/0x390
Aug 7 07:26:16 rx [1006006.532398] __do_softirq+0xd1/0x2c1
Aug 7 07:26:16 rx [1006006.536142] irq_exit+0xae/0xb0
Aug 7 07:26:16 rx [1006006.539452] do_IRQ+0x5a/0xf0
Aug 7 07:26:16 rx [1006006.542590] common_interrupt+0xf/0xf
Aug 7 07:26:16 rx [1006006.546421]
Aug 7 07:26:16 rx [1006006.548695] RIP: 0010:native_safe_halt+0xe/0x10
Aug 7 07:26:16 rx [1006006.553399] Code: 7b ff ff ff eb bd 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 36 2c 50 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 26 2c 50 00 fb f4 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 e8 dd 5e 61 ff 65
Aug 7 07:26:16 rx [1006006.572309] RSP: 0018:ffffb42600177e70 EFLAGS: 00000246 ORIG_RAX: ffffffffffffffc2
Aug 7 07:26:16 rx [1006006.580040] RAX: ffffffff8ed08b20 RBX: 0000000000000005 RCX: 0000000000000001
Aug 7 07:26:16 rx [1006006.587337] RDX: 00000000f48eeca2 RSI: 0000000000000082 RDI: 0000000000000082
Aug 7 07:26:16 rx [1006006.594635] RBP: ffffb42600177e90 R08: 0000000000000000 R09: 000000000000020f
Aug 7 07:26:16 rx [1006006.601931] R10: 0000000000100000 R11: 0000000000000000 R12: 0000000000000005
Aug 7 07:26:16 rx [1006006.609229] R13: ffff93157deb5f00 R14: 0000000000000000 R15: 0000000000000000
Aug 7 07:26:16 rx [1006006.616530] ? __cpuidle_text_start+0x8/0x8
Aug 7 07:26:16 rx [1006006.620886] ? default_idle+0x20/0x140
Aug 7 07:26:16 rx [1006006.624804] arch_cpu_idle+0x15/0x20
Aug 7 07:26:16 rx [1006006.628545] default_idle_call+0x23/0x30
Aug 7 07:26:16 rx [1006006.632640] do_idle+0x1fb/0x270
Aug 7 07:26:16 rx [1006006.636035] cpu_startup_entry+0x20/0x30
Aug 7 07:26:16 rx [1006006.640126] start_secondary+0x178/0x1d0
Aug 7 07:26:16 rx [1006006.644218] secondary_startup_64+0xa4/0xb0
Aug 7 07:26:17 rx [1006006.648568] Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 nft_ct amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif input_leds joydev rndis_host cdc_ether usbnet ast mii drm_vram_helper ttm drm_kms_helper i2c_algo_bit fb_sys_fops syscopyarea sysfillrect sysimgblt ccp mac_hid ipmi_si ipmi_devintf ipmi_msghandler sch_fq_codel nf_tables_set nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 nf_tables nfnetlink ramoops reed_solomon efi_pstore drm ip_tables x_tables autofs4 raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid0 multipath linear mlx5_ib ib_uverbs ib_core raid1 hid_generic mlx5_core pci_hyperv_intf crc32_pclmul usbhid ahci tls mlxfw bnxt_en hid libahci nvme i2c_piix4 nvme_core wmi [last unloaded: cpuid]
Aug 7 07:26:17 rx [1006006.726180] CR2: 0000000000000020
Aug 7 07:26:17 rx [1006006.729718] ---[ end trace e0e2e37e4e612984 ]---

Prior to seeing the first crash and on other machines we also see the warning in
tcp_send_loss_probe() where packets_out is non-zero, but both transmit and retrans
queues are empty so we know the box is seeing some accounting issue in this area:

Jul 26 09:15:27 kernel: ------------[ cut here ]------------
Jul 26 09:15:27 kernel: invalid inflight: 2 state 1 cwnd 68 mss 8988
Jul 26 09:15:27 kernel: WARNING: CPU: 16 PID: 0 at net/ipv4/tcp_output.c:2605 tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: Modules linked in: vrf bridge stp llc vxlan ip6_udp_tunnel udp_tunnel nls_iso8859_1 nft_ct amd64_edac_mod edac_mce_amd kvm_amd kvm crct10dif_pclmul ghash_clmulni_intel aesni_intel crypto_simd cryptd glue_helper wmi_bmof ipmi_ssif joydev input_leds rndis_host cdc_ether usbnet mii ast drm_vram_helper ttm drm_kms_he>
Jul 26 09:15:27 kernel: CPU: 16 PID: 0 Comm: swapper/16 Not tainted 5.4.0-174-generic #193-Ubuntu
Jul 26 09:15:27 kernel: Hardware name: Supermicro SMC 2x26 os-gen8 64C NVME-Y 256G/H12SSW-NTR, BIOS 2.5.V1.2U.NVMe.UEFI 05/09/2023
Jul 26 09:15:27 kernel: RIP: 0010:tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: Code: 08 26 01 00 75 e2 41 0f b6 54 24 12 41 8b 8c 24 c0 06 00 00 45 89 f0 48 c7 c7 e0 b4 20 a7 c6 05 8d 08 26 01 01 e8 4a c0 0f 00 <0f> 0b eb ba 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 55 48 89 e5 41
Jul 26 09:15:27 kernel: RSP: 0018:ffffb7838088ce00 EFLAGS: 00010286
Jul 26 09:15:27 kernel: RAX: 0000000000000000 RBX: ffff9b84b5630430 RCX: 0000000000000006
Jul 26 09:15:27 kernel: RDX: 0000000000000007 RSI: 0000000000000096 RDI: ffff9b8e4621c8c0
Jul 26 09:15:27 kernel: RBP: ffffb7838088ce18 R08: 0000000000000927 R09: 0000000000000004
Jul 26 09:15:27 kernel: R10: 0000000000000000 R11: 0000000000000001 R12: ffff9b84b5630000
Jul 26 09:15:27 kernel: R13: 0000000000000000 R14: 000000000000231c R15: ffff9b84b5630430
Jul 26 09:15:27 kernel: FS: 0000000000000000(0000) GS:ffff9b8e46200000(0000) knlGS:0000000000000000
Jul 26 09:15:27 kernel: CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
Jul 26 09:15:27 kernel: CR2: 000056238cec2380 CR3: 0000003e49ede005 CR4: 0000000000760ee0
Jul 26 09:15:27 kernel: PKRU: 55555554
Jul 26 09:15:27 kernel: Call Trace:
Jul 26 09:15:27 kernel: <IRQ>
Jul 26 09:15:27 kernel: ? show_regs.cold+0x1a/0x1f
Jul 26 09:15:27 kernel: ? __warn+0x98/0xe0
Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: ? report_bug+0xd1/0x100
Jul 26 09:15:27 kernel: ? do_error_trap+0x9b/0xc0
Jul 26 09:15:27 kernel: ? do_invalid_op+0x3c/0x50
Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: ? invalid_op+0x1e/0x30
Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: tcp_write_timer_handler+0x1b4/0x240
Jul 26 09:15:27 kernel: tcp_write_timer+0x9e/0xe0
Jul 26 09:15:27 kernel: ? tcp_write_timer_handler+0x240/0x240
Jul 26 09:15:27 kernel: call_timer_fn+0x32/0x130
Jul 26 09:15:27 kernel: __run_timers.part.0+0x180/0x280
Jul 26 09:15:27 kernel: ? timerqueue_add+0x9b/0xb0
Jul 26 09:15:27 kernel: ? enqueue_hrtimer+0x3d/0x90
Jul 26 09:15:27 kernel: ? do_error_trap+0x9b/0xc0
Jul 26 09:15:27 kernel: ? do_invalid_op+0x3c/0x50
Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: ? invalid_op+0x1e/0x30
Jul 26 09:15:27 kernel: ? tcp_send_loss_probe+0x214/0x220
Jul 26 09:15:27 kernel: tcp_write_timer_handler+0x1b4/0x240
Jul 26 09:15:27 kernel: tcp_write_timer+0x9e/0xe0
Jul 26 09:15:27 kernel: ? tcp_write_timer_handler+0x240/0x240
Jul 26 09:15:27 kernel: call_timer_fn+0x32/0x130
Jul 26 09:15:27 kernel: __run_timers.part.0+0x180/0x280
Jul 26 09:15:27 kernel: ? timerqueue_add+0x9b/0xb0
Jul 26 09:15:27 kernel: ? enqueue_hrtimer+0x3d/0x90
Jul 26 09:15:27 kernel: ? recalibrate_cpu_khz+0x10/0x10
Jul 26 09:15:27 kernel: ? ktime_get+0x3e/0xa0
Jul 26 09:15:27 kernel: ? native_x2apic_icr_write+0x30/0x30
Jul 26 09:15:27 kernel: run_timer_softirq+0x2a/0x50
Jul 26 09:15:27 kernel: __do_softirq+0xd1/0x2c1
Jul 26 09:15:27 kernel: irq_exit+0xae/0xb0
Jul 26 09:15:27 kernel: smp_apic_timer_interrupt+0x7b/0x140
Jul 26 09:15:27 kernel: apic_timer_interrupt+0xf/0x20
Jul 26 09:15:27 kernel: </IRQ>
Jul 26 09:15:27 kernel: RIP: 0010:native_safe_halt+0xe/0x10
Jul 26 09:15:27 kernel: Code: 7b ff ff ff eb bd 90 90 90 90 90 90 e9 07 00 00 00 0f 00 2d 36 2c 50 00 f4 c3 66 90 e9 07 00 00 00 0f 00 2d 26 2c 50 00 fb f4 <c3> 90 0f 1f 44 00 00 55 48 89 e5 41 55 41 54 53 e8 dd 5e 61 ff 65
Jul 26 09:15:27 kernel: RSP: 0018:ffffb783801cfe70 EFLAGS: 00000246 ORIG_RAX: ffffffffffffff13
Jul 26 09:15:27 kernel: RAX: ffffffffa6908b20 RBX: 0000000000000010 RCX: 0000000000000001
Jul 26 09:15:27 kernel: RDX: 000000006fc0c97e RSI: 0000000000000082 RDI: 0000000000000082
Jul 26 09:15:27 kernel: RBP: ffffb783801cfe90 R08: 0000000000000000 R09: 0000000000000225
Jul 26 09:15:27 kernel: R10: 0000000000100000 R11: 0000000000000000 R12: 0000000000000010
Jul 26 09:15:27 kernel: R13: ffff9b8e390b0000 R14: 0000000000000000 R15: 0000000000000000
Jul 26 09:15:27 kernel: ? __cpuidle_text_start+0x8/0x8
Jul 26 09:15:27 kernel: ? default_idle+0x20/0x140
Jul 26 09:15:27 kernel: arch_cpu_idle+0x15/0x20
Jul 26 09:15:27 kernel: default_idle_call+0x23/0x30
Jul 26 09:15:27 kernel: do_idle+0x1fb/0x270
Jul 26 09:15:27 kernel: cpu_startup_entry+0x20/0x30
Jul 26 09:15:27 kernel: start_secondary+0x178/0x1d0
Jul 26 09:15:27 kernel: secondary_startup_64+0xa4/0xb0
Jul 26 09:15:27 kernel: ---[ end trace e7ac822987e33be1 ]---

The NULL ptr deref is coming from tcp_rto_delta_us() attempting to pull an skb
off the head of the retransmit queue and then dereferencing that skb to get the
skb_mstamp_ns value via tcp_skb_timestamp_us(skb).

The crash is the same one that was reported a # of years ago here:
https://lore.kernel.org/netdev/86c0f836-9a7c-438b-d81a-839be45f1f58@gmail.com/T/#t

and the kernel we're running has the fix which was added to resolve this issue.

Unfortunately we've been unsuccessful so far in reproducing this problem in the
lab and do not have the luxury of pushing out a new kernel to try and test if
newer kernels resolve this issue at the moment. I realize this is a report
against both an Ubuntu kernel and also an older 5.4 kernel. I have reported this
issue to Ubuntu here: https://bugs.launchpad.net/ubuntu/+source/linux/+bug/2077657
however I feel like since this issue has possibly cropped up again it makes
sense to build in some protection in this path (even on the latest kernel
versions) since the code in question just blindly assumes there's a valid skb
without testing if it's NULL b/f it looks at the timestamp.

Given we have seen crashes in this path before and now this case it seems like
we should protect ourselves for when packets_out accounting is incorrect.
While we should fix that root cause we should also just make sure the skb
is not NULL before dereferencing it. Also add a warn once here to capture
some information if/when the problem case is hit again.

Fixes: e1a10ef7fa87 ("tcp: introduce tcp_rto_delta_us() helper for xmit timer fix")
Signed-off-by: Josh Hunt <johunt@akamai.com>
Acked-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: factor out __tcp_close() helper 2024-03-01T12:13:34+00:00 Paolo Abeni pabeni@redhat.com 2020-11-16T09:48:04+00:00 5a9dc14df2ef3771d62e41a32c4a72417d845c07 [ Upstream commit 77c3c95637526f1e4330cc9a4b2065f668c2c4fe ] unlocked version of protocol level close, will be used by MPTCP to allow decouple orphaning and subflow level close. Signed-off-by: Paolo Abeni <pabeni@redhat.com> Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 77c3c95637526f1e4330cc9a4b2065f668c2c4fe ]

unlocked version of protocol level close, will be used by
MPTCP to allow decouple orphaning and subflow level close.

Signed-off-by: Paolo Abeni <pabeni@redhat.com>
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: fix cookie_init_timestamp() overflows 2023-11-20T09:30:10+00:00 Eric Dumazet edumazet@google.com 2023-10-20T12:57:37+00:00 5105d46146f26f3b67307bea182734f12a63d76d [ Upstream commit 73ed8e03388d16c12fc577e5c700b58a29045a15 ] cookie_init_timestamp() is supposed to return a 64bit timestamp suitable for both TSval determination and setting of skb->tstamp. Unfortunately it uses 32bit fields and overflows after 2^32 * 10^6 nsec (~49 days) of uptime. Generated TSval are still correct, but skb->tstamp might be set far away in the past, potentially confusing other layers. tcp_ns_to_ts() is changed to return a full 64bit value, ts and ts_now variables are changed to u64 type, and TSMASK is removed in favor of shifts operations. While we are at it, change this sequence: ts >>= TSBITS; ts--; ts <<= TSBITS; ts |= options; to: ts -= (1UL << TSBITS); Fixes: 9a568de4818d ("tcp: switch TCP TS option (RFC 7323) to 1ms clock") Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 73ed8e03388d16c12fc577e5c700b58a29045a15 ]

cookie_init_timestamp() is supposed to return a 64bit timestamp
suitable for both TSval determination and setting of skb->tstamp.

Unfortunately it uses 32bit fields and overflows after
2^32 * 10^6 nsec (~49 days) of uptime.

Generated TSval are still correct, but skb->tstamp might be set
far away in the past, potentially confusing other layers.

tcp_ns_to_ts() is changed to return a full 64bit value,
ts and ts_now variables are changed to u64 type,
and TSMASK is removed in favor of shifts operations.

While we are at it, change this sequence:
		ts >>= TSBITS;
		ts--;
		ts <<= TSBITS;
		ts |= options;
to:
		ts -= (1UL << TSBITS);

Fixes: 9a568de4818d ("tcp: switch TCP TS option (RFC 7323) to 1ms clock")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: Remove one extra ktime_get_ns() from cookie_init_timestamp 2023-11-20T09:30:09+00:00 Eric Dumazet edumazet@google.com 2019-11-07T19:51:18+00:00 e4e819bdc8f3674cbdc295b670307c0dd981e440 [ Upstream commit 200ecef67b8d09d16ec55f91c92751dcc7a38d40 ] tcp_make_synack() already uses tcp_clock_ns(), and can pass the value to cookie_init_timestamp() to avoid another call to ktime_get_ns() helper. Signed-off-by: Eric Dumazet <edumazet@google.com> Signed-off-by: David S. Miller <davem@davemloft.net> Stable-dep-of: 73ed8e03388d ("tcp: fix cookie_init_timestamp() overflows") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 200ecef67b8d09d16ec55f91c92751dcc7a38d40 ]

tcp_make_synack() already uses tcp_clock_ns(), and can pass
the value to cookie_init_timestamp() to avoid another call
to ktime_get_ns() helper.

Signed-off-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 73ed8e03388d ("tcp: fix cookie_init_timestamp() overflows")
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: fix excessive TLP and RACK timeouts from HZ rounding 2023-10-25T09:53:21+00:00 Neal Cardwell ncardwell@google.com 2023-10-15T17:47:00+00:00 1ae2c7d44e7e9a9f16bd629eecf9017cfdac5eed commit 1c2709cfff1dedbb9591e989e2f001484208d914 upstream. We discovered from packet traces of slow loss recovery on kernels with the default HZ=250 setting (and min_rtt < 1ms) that after reordering, when receiving a SACKed sequence range, the RACK reordering timer was firing after about 16ms rather than the desired value of roughly min_rtt/4 + 2ms. The problem is largely due to the RACK reorder timer calculation adding in TCP_TIMEOUT_MIN, which is 2 jiffies. On kernels with HZ=250, this is 2*4ms = 8ms. The TLP timer calculation has the exact same issue. This commit fixes the TLP transmit timer and RACK reordering timer floor calculation to more closely match the intended 2ms floor even on kernels with HZ=250. It does this by adding in a new TCP_TIMEOUT_MIN_US floor of 2000 us and then converting to jiffies, instead of the current approach of converting to jiffies and then adding th TCP_TIMEOUT_MIN value of 2 jiffies. Our testing has verified that on kernels with HZ=1000, as expected, this does not produce significant changes in behavior, but on kernels with the default HZ=250 the latency improvement can be large. For example, our tests show that for HZ=250 kernels at low RTTs this fix roughly halves the latency for the RACK reorder timer: instead of mostly firing at 16ms it mostly fires at 8ms. Suggested-by: Eric Dumazet <edumazet@google.com> Signed-off-by: Neal Cardwell <ncardwell@google.com> Signed-off-by: Yuchung Cheng <ycheng@google.com> Fixes: bb4d991a28cc ("tcp: adjust tail loss probe timeout") Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20231015174700.2206872-1-ncardwell.sw@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 1c2709cfff1dedbb9591e989e2f001484208d914 upstream.

We discovered from packet traces of slow loss recovery on kernels with
the default HZ=250 setting (and min_rtt < 1ms) that after reordering,
when receiving a SACKed sequence range, the RACK reordering timer was
firing after about 16ms rather than the desired value of roughly
min_rtt/4 + 2ms. The problem is largely due to the RACK reorder timer
calculation adding in TCP_TIMEOUT_MIN, which is 2 jiffies. On kernels
with HZ=250, this is 2*4ms = 8ms. The TLP timer calculation has the
exact same issue.

This commit fixes the TLP transmit timer and RACK reordering timer
floor calculation to more closely match the intended 2ms floor even on
kernels with HZ=250. It does this by adding in a new
TCP_TIMEOUT_MIN_US floor of 2000 us and then converting to jiffies,
instead of the current approach of converting to jiffies and then
adding th TCP_TIMEOUT_MIN value of 2 jiffies.

Our testing has verified that on kernels with HZ=1000, as expected,
this does not produce significant changes in behavior, but on kernels
with the default HZ=250 the latency improvement can be large. For
example, our tests show that for HZ=250 kernels at low RTTs this fix
roughly halves the latency for the RACK reorder timer: instead of
mostly firing at 16ms it mostly fires at 8ms.

Suggested-by: Eric Dumazet <edumazet@google.com>
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Signed-off-by: Yuchung Cheng <ycheng@google.com>
Fixes: bb4d991a28cc ("tcp: adjust tail loss probe timeout")
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231015174700.2206872-1-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
tcp: fix quick-ack counting to count actual ACKs of new data 2023-10-10T19:46:44+00:00 Neal Cardwell ncardwell@google.com 2023-10-01T15:12:38+00:00 2791d64e6607abe78051570988cfe7c6a419ebd7 [ Upstream commit 059217c18be6757b95bfd77ba53fb50b48b8a816 ] This commit fixes quick-ack counting so that it only considers that a quick-ack has been provided if we are sending an ACK that newly acknowledges data. The code was erroneously using the number of data segments in outgoing skbs when deciding how many quick-ack credits to remove. This logic does not make sense, and could cause poor performance in request-response workloads, like RPC traffic, where requests or responses can be multi-segment skbs. When a TCP connection decides to send N quick-acks, that is to accelerate the cwnd growth of the congestion control module controlling the remote endpoint of the TCP connection. That quick-ack decision is purely about the incoming data and outgoing ACKs. It has nothing to do with the outgoing data or the size of outgoing data. And in particular, an ACK only serves the intended purpose of allowing the remote congestion control to grow the congestion window quickly if the ACK is ACKing or SACKing new data. The fix is simple: only count packets as serving the goal of the quickack mechanism if they are ACKing/SACKing new data. We can tell whether this is the case by checking inet_csk_ack_scheduled(), since we schedule an ACK exactly when we are ACKing/SACKing new data. Fixes: fc6415bcb0f5 ("[TCP]: Fix quick-ack decrementing with TSO.") Signed-off-by: Neal Cardwell <ncardwell@google.com> Reviewed-by: Yuchung Cheng <ycheng@google.com> Reviewed-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20231001151239.1866845-1-ncardwell.sw@gmail.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 059217c18be6757b95bfd77ba53fb50b48b8a816 ]

This commit fixes quick-ack counting so that it only considers that a
quick-ack has been provided if we are sending an ACK that newly
acknowledges data.

The code was erroneously using the number of data segments in outgoing
skbs when deciding how many quick-ack credits to remove. This logic
does not make sense, and could cause poor performance in
request-response workloads, like RPC traffic, where requests or
responses can be multi-segment skbs.

When a TCP connection decides to send N quick-acks, that is to
accelerate the cwnd growth of the congestion control module
controlling the remote endpoint of the TCP connection. That quick-ack
decision is purely about the incoming data and outgoing ACKs. It has
nothing to do with the outgoing data or the size of outgoing data.

And in particular, an ACK only serves the intended purpose of allowing
the remote congestion control to grow the congestion window quickly if
the ACK is ACKing or SACKing new data.

The fix is simple: only count packets as serving the goal of the
quickack mechanism if they are ACKing/SACKing new data. We can tell
whether this is the case by checking inet_csk_ack_scheduled(), since
we schedule an ACK exactly when we are ACKing/SACKing new data.

Fixes: fc6415bcb0f5 ("[TCP]: Fix quick-ack decrementing with TSO.")
Signed-off-by: Neal Cardwell <ncardwell@google.com>
Reviewed-by: Yuchung Cheng <ycheng@google.com>
Reviewed-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20231001151239.1866845-1-ncardwell.sw@gmail.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: tcp_enter_quickack_mode() should be static 2023-09-23T08:59:41+00:00 Eric Dumazet edumazet@google.com 2023-07-18T16:20:49+00:00 57935355dc67bc64958e0075a228deb0e2267235 [ Upstream commit 03b123debcbc8db987bda17ed8412cc011064c22 ] After commit d2ccd7bc8acd ("tcp: avoid resetting ACK timer in DCTCP"), tcp_enter_quickack_mode() is only used from net/ipv4/tcp_input.c. Fixes: d2ccd7bc8acd ("tcp: avoid resetting ACK timer in DCTCP") Signed-off-by: Eric Dumazet <edumazet@google.com> Cc: Yuchung Cheng <ycheng@google.com> Cc: Neal Cardwell <ncardwell@google.com> Link: https://lore.kernel.org/r/20230718162049.1444938-1-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 03b123debcbc8db987bda17ed8412cc011064c22 ]

After commit d2ccd7bc8acd ("tcp: avoid resetting ACK timer in DCTCP"),
tcp_enter_quickack_mode() is only used from net/ipv4/tcp_input.c.

Fixes: d2ccd7bc8acd ("tcp: avoid resetting ACK timer in DCTCP")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Cc: Yuchung Cheng <ycheng@google.com>
Cc: Neal Cardwell <ncardwell@google.com>
Link: https://lore.kernel.org/r/20230718162049.1444938-1-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp: annotate data-races around tp->notsent_lowat 2023-07-27T06:37:45+00:00 Eric Dumazet edumazet@google.com 2023-07-19T21:28:55+00:00 21c325d01ecceb882fffc1e67b445e9611eab918 [ Upstream commit 1aeb87bc1440c5447a7fa2d6e3c2cca52cbd206b ] tp->notsent_lowat can be read locklessly from do_tcp_getsockopt() and tcp_poll(). Fixes: c9bee3b7fdec ("tcp: TCP_NOTSENT_LOWAT socket option") Signed-off-by: Eric Dumazet <edumazet@google.com> Link: https://lore.kernel.org/r/20230719212857.3943972-10-edumazet@google.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit 1aeb87bc1440c5447a7fa2d6e3c2cca52cbd206b ]

tp->notsent_lowat can be read locklessly from do_tcp_getsockopt()
and tcp_poll().

Fixes: c9bee3b7fdec ("tcp: TCP_NOTSENT_LOWAT socket option")
Signed-off-by: Eric Dumazet <edumazet@google.com>
Link: https://lore.kernel.org/r/20230719212857.3943972-10-edumazet@google.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Sasha Levin <sashal@kernel.org>
net: Replace the limit of TCP_LINGER2 with TCP_FIN_TIMEOUT_MAX 2023-07-27T06:37:44+00:00 Cambda Zhu cambda@linux.alibaba.com 2020-04-24T08:06:16+00:00 b1cd5655fc1366760b4e5262955e20360662bb72 [ Upstream commit f0628c524fd188c3f9418e12478dfdfadacba815 ] This patch changes the behavior of TCP_LINGER2 about its limit. The sysctl_tcp_fin_timeout used to be the limit of TCP_LINGER2 but now it's only the default value. A new macro named TCP_FIN_TIMEOUT_MAX is added as the limit of TCP_LINGER2, which is 2 minutes. Since TCP_LINGER2 used sysctl_tcp_fin_timeout as the default value and the limit in the past, the system administrator cannot set the default value for most of sockets and let some sockets have a greater timeout. It might be a mistake that let the sysctl to be the limit of the TCP_LINGER2. Maybe we can add a new sysctl to set the max of TCP_LINGER2, but FIN-WAIT-2 timeout is usually no need to be too long and 2 minutes are legal considering TCP specs. Changes in v3: - Remove the new socket option and change the TCP_LINGER2 behavior so that the timeout can be set to value between sysctl_tcp_fin_timeout and 2 minutes. Changes in v2: - Add int overflow check for the new socket option. Changes in v1: - Add a new socket option to set timeout greater than sysctl_tcp_fin_timeout. Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com> Signed-off-by: David S. Miller <davem@davemloft.net> Stable-dep-of: 9df5335ca974 ("tcp: annotate data-races around tp->linger2") Signed-off-by: Sasha Levin <sashal@kernel.org> 
[ Upstream commit f0628c524fd188c3f9418e12478dfdfadacba815 ]

This patch changes the behavior of TCP_LINGER2 about its limit. The
sysctl_tcp_fin_timeout used to be the limit of TCP_LINGER2 but now it's
only the default value. A new macro named TCP_FIN_TIMEOUT_MAX is added
as the limit of TCP_LINGER2, which is 2 minutes.

Since TCP_LINGER2 used sysctl_tcp_fin_timeout as the default value
and the limit in the past, the system administrator cannot set the
default value for most of sockets and let some sockets have a greater
timeout. It might be a mistake that let the sysctl to be the limit of
the TCP_LINGER2. Maybe we can add a new sysctl to set the max of
TCP_LINGER2, but FIN-WAIT-2 timeout is usually no need to be too long
and 2 minutes are legal considering TCP specs.

Changes in v3:
- Remove the new socket option and change the TCP_LINGER2 behavior so
  that the timeout can be set to value between sysctl_tcp_fin_timeout
  and 2 minutes.

Changes in v2:
- Add int overflow check for the new socket option.

Changes in v1:
- Add a new socket option to set timeout greater than
  sysctl_tcp_fin_timeout.

Signed-off-by: Cambda Zhu <cambda@linux.alibaba.com>
Signed-off-by: David S. Miller <davem@davemloft.net>
Stable-dep-of: 9df5335ca974 ("tcp: annotate data-races around tp->linger2")
Signed-off-by: Sasha Levin <sashal@kernel.org>
tcp/udp: Make early_demux back namespacified. 2022-11-10T16:57:55+00:00 Kuniyuki Iwashima kuniyu@amazon.com 2022-07-13T17:52:07+00:00 fe3da74428bff06e04214d2478e505ab60987a99 commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d upstream. Commit e21145a9871a ("ipv4: namespacify ip_early_demux sysctl knob") made it possible to enable/disable early_demux on a per-netns basis. Then, we introduced two knobs, tcp_early_demux and udp_early_demux, to switch it for TCP/UDP in commit dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp"). However, the .proc_handler() was wrong and actually disabled us from changing the behaviour in each netns. We can execute early_demux if net.ipv4.ip_early_demux is on and each proto .early_demux() handler is not NULL. When we toggle (tcp|udp)_early_demux, the change itself is saved in each netns variable, but the .early_demux() handler is a global variable, so the handler is switched based on the init_net's sysctl variable. Thus, netns (tcp|udp)_early_demux knobs have nothing to do with the logic. Whether we CAN execute proto .early_demux() is always decided by init_net's sysctl knob, and whether we DO it or not is by each netns ip_early_demux knob. This patch namespacifies (tcp|udp)_early_demux again. For now, the users of the .early_demux() handler are TCP and UDP only, and they are called directly to avoid retpoline. So, we can remove the .early_demux() handler from inet6?_protos and need not dereference them in ip6?_rcv_finish_core(). If another proto needs .early_demux(), we can restore it at that time. Fixes: dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp") Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com> Link: https://lore.kernel.org/r/20220713175207.7727-1-kuniyu@amazon.com Signed-off-by: Jakub Kicinski <kuba@kernel.org> Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org> 
commit 11052589cf5c0bab3b4884d423d5f60c38fcf25d upstream.

Commit e21145a9871a ("ipv4: namespacify ip_early_demux sysctl knob") made
it possible to enable/disable early_demux on a per-netns basis.  Then, we
introduced two knobs, tcp_early_demux and udp_early_demux, to switch it for
TCP/UDP in commit dddb64bcb346 ("net: Add sysctl to toggle early demux for
tcp and udp").  However, the .proc_handler() was wrong and actually
disabled us from changing the behaviour in each netns.

We can execute early_demux if net.ipv4.ip_early_demux is on and each proto
.early_demux() handler is not NULL.  When we toggle (tcp|udp)_early_demux,
the change itself is saved in each netns variable, but the .early_demux()
handler is a global variable, so the handler is switched based on the
init_net's sysctl variable.  Thus, netns (tcp|udp)_early_demux knobs have
nothing to do with the logic.  Whether we CAN execute proto .early_demux()
is always decided by init_net's sysctl knob, and whether we DO it or not is
by each netns ip_early_demux knob.

This patch namespacifies (tcp|udp)_early_demux again.  For now, the users
of the .early_demux() handler are TCP and UDP only, and they are called
directly to avoid retpoline.  So, we can remove the .early_demux() handler
from inet6?_protos and need not dereference them in ip6?_rcv_finish_core().
If another proto needs .early_demux(), we can restore it at that time.

Fixes: dddb64bcb346 ("net: Add sysctl to toggle early demux for tcp and udp")
Signed-off-by: Kuniyuki Iwashima <kuniyu@amazon.com>
Link: https://lore.kernel.org/r/20220713175207.7727-1-kuniyu@amazon.com
Signed-off-by: Jakub Kicinski <kuba@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>