zero-copy AF_XDP: call trace when creating a stack on down'ed interface

[ol-sergeyn]

I see a call trace when creating a zerocopy AF_XDP stack after putting interface down:

[66120.916580] BUG: kernel NULL pointer dereference, address: 00000000000002a0
[66120.925276] #PF: supervisor write access in kernel mode
[66120.932024] #PF: error_code(0x0002) - not-present page
[66120.938681] PGD 800000023b1b6067 P4D 800000023b1b6067 PUD 0
[66120.945931] Oops: 0002 [#1] SMP PTI
[66120.950756] CPU: 3 PID: 103598 Comm: nc Tainted: G           OE     5.15.0-79-generic #86-Ubuntu
[66120.961517] Hardware name: Dell Inc. PowerEdge R230/0FRVY0, BIOS 2.3.2 11/16/2017
[66120.970832] RIP: 0010:efx_xdp+0x96/0x1c0 [sfc]
[66120.976782] Code: b2 d0 00 00 00 31 d2 e8 48 ff f5 eb 41 89 c4 85 c0 75 26 4c 89 ef 44 89 f6 e8 a6 11 fd ff 83 bb f8 00 00 00 04 49 89 c5 74 7f <c6> 80 a0 02 00 00 01 eb 06 41 bc ea ff ff ff 5b 44 89 e0 41 5c 41
[66120.999708] RSP: 0018:ffffb1e180ad3a80 EFLAGS: 00010293
[66121.006501] RAX: 0000000000000000 RBX: ffff9c04a1c8f000 RCX: ffff9c04a1c8f120
[66121.015417] RDX: 000000000001fff8 RSI: 0000000000000000 RDI: ffff9c04a1c8f040
[66121.024328] RBP: ffffb1e180ad3aa8 R08: 0000000000000006 R09: 0000000000000020
[66121.033250] R10: ffffe2d909026808 R11: 0000000000000000 R12: 0000000000000000
[66121.042165] R13: 0000000000000000 R14: 0000000000000000 R15: ffff9c04ff280000
[66121.051082] FS:  00007f24bcc3e340(0000) GS:ffff9c0527d80000(0000) knlGS:0000000000000000
[66121.061071] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[66121.068429] CR2: 00000000000002a0 CR3: 000000023e940005 CR4: 00000000003706e0
[66121.077323] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[66121.086184] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
[66121.095041] Call Trace:
[66121.098659]  <TASK>
[66121.101881]  xp_assign_dev+0xfe/0x200
[66121.106842]  xsk_bind+0x159/0x4a0
[66121.111402]  ? fput+0x13/0x20
[66121.115562]  kernel_bind+0x13/0x20
[66121.120193]  af_xdp_init+0x592/0x800 [sfc_resource]
[66121.126471]  efrm_vi_resource_deferred+0x4a/0x70 [sfc_resource]
[66121.133897]  deferred_vis+0xaa/0x470 [onload]
[66121.139585]  tcp_helper_rm_alloc+0x1e8c/0x33b0 [onload]
[66121.146221]  ? oo_version_check_impl+0xb2/0x2c0 [onload]
[66121.152936]  tcp_helper_rm_alloc_proxy+0x122/0x270 [onload]
[66121.159941]  tcp_helper_alloc_ul+0x65/0x90 [onload]
[66121.166162]  tcp_helper_alloc_rsop+0x44/0x130 [onload]
[66121.172668]  oo_fop_unlocked_ioctl+0x144/0x370 [onload]
[66121.179261]  ? __do_sys_memfd_create+0x178/0x260
[66121.185148]  __x64_sys_ioctl+0x92/0xd0
[66121.190041]  do_syscall_64+0x59/0xc0
[66121.194731]  ? do_syscall_64+0x69/0xc0
[66121.199607]  ? do_syscall_64+0x69/0xc0
[66121.204479]  ? irqentry_exit+0x1d/0x30
[66121.209344]  ? exc_page_fault+0x89/0x170
[66121.214398]  entry_SYSCALL_64_after_hwframe+0x61/0xcb
[66121.220700] RIP: 0033:0x7f24bcd69aff
[66121.225337] Code: 00 48 89 44 24 18 31 c0 48 8d 44 24 60 c7 04 24 10 00 00 00 48 89 44 24 08 48 8d 44 24 20 48 89 44 24 10 b8 10 00 00 00 0f 05 <41> 89 c0 3d 00 f0 ff ff 77 1f 48 8b 44 24 18 64 48 2b 04 25 28 00
[66121.247679] RSP: 002b:00007fffac3ceec0 EFLAGS: 00000246 ORIG_RAX: 0000000000000010
[66121.256811] RAX: ffffffffffffffda RBX: 00007f24bcc3d6c0 RCX: 00007f24bcd69aff
[66121.265460] RDX: 00007fffac3cef30 RSI: 00000000c0b85a1c RDI: 0000000000000004
[66121.274111] RBP: 0000000000000004 R08: 00007fffac3cedb0 R09: 0000000000000000
[66121.282758] R10: 0000000000000000 R11: 0000000000000246 R12: 00005586b1e504c0
[66121.291403] R13: 00000000c0b85a1c R14: 00007fffac3cef30 R15: 0000000000000000
[66121.300043]  </TASK>
[66121.303132] Modules linked in: onload(OE) sfc_char(OE) sfc_resource(OE) sfc(OE) sfc_driverlink(OE) cmdlinepart nf_flow_table nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 vdpa mtdblock mtd_blkdevs hwmon_vid crc32_generic mii tls nf_tables rpcsec_gss_krb5 nfsv4 nfs lockd grace fscache netfs nfnetlink overlay 8021q garp mrp stp llc binfmt_misc irdma ice ib_uverbs ib_core ipmi_ssif dell_wmi ledtrig_audio intel_rapl_msr mei_me ee1004 dell_smbios intel_rapl_common dell_wmi_descriptor mei ie31200_edac sparse_keymap intel_tcc_cooling x86_pkg_temp_thermal intel_powerclamp intel_pch_thermal dcdbas mac_hid coretemp acpi_power_meter kvm_intel kvm ipmi_si intel_wmi_thunderbolt rapl intel_cstate sch_fq_codel dm_multipath scsi_dh_rdac scsi_dh_emc scsi_dh_alua ipmi_watchdog ipmi_devintf ipmi_msghandler efi_pstore auth_rpcgss sunrpc ip_tables x_tables autofs4 btrfs blake2b_generic zstd_compress raid10 raid456 async_raid6_recov async_memcpy async_pq async_xor async_tx xor raid6_pq libcrc32c raid1 raid0
[66121.303186]  multipath linear mgag200 i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt crct10dif_pclmul crc32_pclmul fb_sys_fops ghash_clmulni_intel cec rc_core ahci aesni_intel crypto_simd i2c_i801 libahci cryptd i2c_smbus xhci_pci drm tg3 xhci_pci_renesas mtd i40e mdio wmi video [last unloaded: sfc_driverlink]
[66121.440790] CR2: 00000000000002a0
[66121.445310] ---[ end trace 342137a00cac4ab7 ]---
[66121.489293] RIP: 0010:efx_xdp+0x96/0x1c0 [sfc]
[66121.495123] Code: b2 d0 00 00 00 31 d2 e8 48 ff f5 eb 41 89 c4 85 c0 75 26 4c 89 ef 44 89 f6 e8 a6 11 fd ff 83 bb f8 00 00 00 04 49 89 c5 74 7f <c6> 80 a0 02 00 00 01 eb 06 41 bc ea ff ff ff 5b 44 89 e0 41 5c 41
[66121.517824] RSP: 0018:ffffb1e180ad3a80 EFLAGS: 00010293
[66121.524540] RAX: 0000000000000000 RBX: ffff9c04a1c8f000 RCX: ffff9c04a1c8f120
[66121.533404] RDX: 000000000001fff8 RSI: 0000000000000000 RDI: ffff9c04a1c8f040
[66121.542267] RBP: ffffb1e180ad3aa8 R08: 0000000000000006 R09: 0000000000000020
[66121.551137] R10: ffffe2d909026808 R11: 0000000000000000 R12: 0000000000000000
[66121.560002] R13: 0000000000000000 R14: 0000000000000000 R15: ffff9c04ff280000
[66121.568863] FS:  00007f24bcc3e340(0000) GS:ffff9c0527d80000(0000) knlGS:0000000000000000
[66121.578801] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[66121.586119] CR2: 00000000000002a0 CR3: 000000023e940005 CR4: 00000000003706e0
[66121.594995] DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
[66121.603865] DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400

SFC NIC.
Onload master 76e6c7d

How to reproduce:

# Load and register
$ RESOURCE_OPT="enable_driverlink=0" sudo ./build/x86_64_linux-5.15.0-79-generic/driver/linux/load.sh onload
$ echo enp2s0f0 | sudo tee /sys/module/sfc_resource/afxdp/register

# Set interface down
$ sudo ip li set enp2s0f0 down

# Run netcat
$ EF_AF_XDP_ZEROCOPY=1 sudo onload nc -l 6666