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Wed, 06 Aug 2025 14:16:22 -0700 (PDT) Date: Wed, 6 Aug 2025 16:16:18 -0500 From: Corey Minyard To: Fred Lawler Cc: openipmi-developer@lists.sourceforge.net, linux-kernel@vger.kernel.org, kernel-team@cloudflare.com Subject: Re: [BUG] ipmi_si: watchdog: Watchdog detected hard LOCKUP Message-ID: Reply-To: corey@minyard.net References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Disposition: inline Content-Transfer-Encoding: quoted-printable In-Reply-To: On Wed, Aug 06, 2025 at 03:19:02PM -0500, Fred Lawler wrote: > + CC: Corey Minyard >=20 > Misspelled the email address. >=20 > On Wed, Aug 6, 2025 at 3:14=E2=80=AFPM Frederick Lawler wrote: > > > > Hi Corey, > > > > In kernel 6.12.y, while resetting the BMC, we can sometimes hit a hard = LOCKUP > > watchdog event, especially so while querying the BMC for basic device > > information via sysfs. > > > > I havn't been able to create a consistent reproducer yet, but I suspect > > that these occur during high traffic, BMC is resetting, and reading > > from the sysfs files in parallel. We're also using KCS to interface > > with the BMC. > > > > I can consistently reproduce hung tasks trivially with the following, > > during a BMC reset: > > > > while true; do cat aux_firmware_revision &>/dev/null; done & I looked through the code around this and didn't see anything obvious. Looking at the logs a bit more: [ 904.196122] [ C33] watchdog: Watchdog detected hard LOCKUP on cpu 33 [ 904.196127] [ C97] Uhhuh. NMI received for unknown reason 3d on CPU = 97. So there's a lockup on CPU 33, but the backtrace shows it's in the ACPI idle function. That's wierd. For that to really happen, it would have to lock up in ACPI. The unknown NMIs are also wierd. Are you using the IPMI NMI watchdog? I'm wondering if something is happening with the BMC resetting and interactions with ACPI involved in that. Adding the extra part of trying to talk to the BMC while it's being reset could cause the BMC to get confused and do bad things? > > > > I tried also tried to load the CPUs with stress-ng, but the best I can = do > > are the hung tasks. > > > > I identified that sni_send()[1] could be locked behind the > > spin_lock_irqsave() and within the KCS send handler, there's another irq > > save lock. I suspect this is where we're getting hung up. Below is a > > sample stack trace + log output. Yeah, I don't see that in the traceback. There is a lock in the KCS sender, but I don't see how that could do anything. Maybe you could try changing the cpuidle handler? That would be at least something to try. -corey > > > > I'm happy to provide traces and additional information, let me know. > > > > Links: > > [1]: https://git.kernel.org/pub/scm/linux/kernel/git/stable/linux.git/t= ree/drivers/char/ipmi/ipmi_msghandler.c?h=3Dlinux-6.12.y#n1899 > > > > [ 499.564572] [ T27255] ip6_tunnel: pni_gre_814 xmit: Local address n= ot yet configured! > > [ 499.588176] [ T27255] ip6_tunnel: pni_gre_868 xmit: Local address n= ot yet configured! > > [ 499.605284] [ T27255] ip6_tunnel: pni_gre_871 xmit: Local address n= ot yet configured! > > [ 805.906999] [ T12765] usb 1-1: USB disconnect, device number 2 > > [ 845.346020] [ T12765] usb 1-1: new high-speed USB device number 3 u= sing xhci_hcd > > [ 845.485453] [ T12765] usb 1-1: New USB device found, idVendor=3D1d6= b, idProduct=3D0107, bcdDevice=3D 1.00 > > [ 845.496823] [ T12765] usb 1-1: New USB device strings: Mfr=3D3, Pro= duct=3D2, SerialNumber=3D1 > > [ 845.507242] [ T12765] usb 1-1: Product: USB Virtual Hub > > [ 845.514946] [ T12765] usb 1-1: Manufacturer: Aspeed > > [ 845.522363] [ T12765] usb 1-1: SerialNumber: 00000000 > > [ 845.530454] [ T12765] usb 1-1: Device is not authorized for usage > > [ 853.774910] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.783794] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.792649] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.801461] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.810291] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.819069] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.827816] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.836581] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.845326] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.854074] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 853.862813] [ C119] ipmi_si IPI0001:00: KCS in invalid state 6 > > [ 863.934436] [ T124929] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 863.943420] [ T124929] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 863.952363] [ T124929] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 863.961296] [ T124929] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 878.616336] [ T126542] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 878.624905] [ T126542] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 878.633427] [ T126542] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 878.641954] [ T126542] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 880.310112] [ T126681] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 880.318682] [ T126681] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 880.327083] [ T126681] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 880.335483] [ T126681] ipmi_si IPI0001:00: KCS in invalid state 7 > > [ 904.196122] [ C33] watchdog: Watchdog detected hard LOCKUP on cp= u 33 > > [ 904.196127] [ C97] Uhhuh. NMI received for unknown reason 3d on = CPU 97. > > [ 904.196126] [ C6] Uhhuh. NMI received for unknown reason 3d on = CPU 6. > > [ 904.196130] [ C33] Modules linked in: > > [ 904.196129] [ C101] Uhhuh. NMI received for unknown reason 3d on = CPU 101. > > [ 904.196131] [ C97] Dazed and confused, but trying to continue > > [ 904.196131] [ C33] nft_fwd_netdev > > [ 904.196131] [ C99] Uhhuh. NMI received for unknown reason 2d on = CPU 99. > > [ 904.196133] [ C6] Dazed and confused, but trying to continue > > [ 904.196133] [ C102] Uhhuh. NMI received for unknown reason 2d on = CPU 102. > > [ 904.196134] [ C33] nf_dup_netdev > > [ 904.196134] [ C35] Uhhuh. NMI received for unknown reason 2d on = CPU 35. > > [ 904.196135] [ C101] Dazed and confused, but trying to continue > > [ 904.196137] [ C99] Dazed and confused, but trying to continue > > [ 904.196137] [ C33] xfrm_interface > > [ 904.196136] [ C69] Uhhuh. NMI received for unknown reason 2d on = CPU 69. > > [ 904.196140] [ C102] Dazed and confused, but trying to continue > > [ 904.196140] [ C33] xfrm6_tunnel > > [ 904.196138] [ C121] Uhhuh. NMI received for unknown reason 2d on = CPU 121. > > [ 904.196140] [ C123] Uhhuh. NMI received for unknown reason 2d on = CPU 123. > > [ 904.196142] [ C35] Dazed and confused, but trying to continue > > [ 904.196143] [ C69] Dazed and confused, but trying to continue > > [ 904.196143] [ C33] nft_numgen > > [ 904.196143] [ C61] Uhhuh. NMI received for unknown reason 2d on = CPU 61. > > [ 904.196144] [ C62] Uhhuh. NMI received for unknown reason 3d on = CPU 62. > > [ 904.196146] [ C123] Dazed and confused, but trying to continue > > [ 904.196147] [ C121] Dazed and confused, but trying to continue > > [ 904.196148] [ C58] Dazed and confused, but trying to continue > > [ 904.196150] [ C33] nft_log nft_limit sit dummy ipip tunnel4 ip_= gre gre xfrm_user xfrm_algo tls mpls_iptunnel mpls_router nft_ct nf_tables = iptable_raw iptable_nat iptable_mangle ipt_REJECT nf_reject_ipv4 ip6table_s= ecurity xt_CT ip6table_raw xt_nat ip6table_nat nf_nat xt_TCPMSS xt_owner xt= _DSCP xt_NFLOG xt_connbytes xt_connlabel xt_statistic xt_connmark ip6table_= mangle xt_limit xt_LOG nf_log_syslog xt_mark xt_conntrack ip6t_REJECT nf_re= ject_ipv6 xt_multiport xt_set xt_tcpmss xt_comment xt_tcpudp ip6table_filte= r ip6_tables nfnetlink_log udp_diag dm_thin_pool dm_persistent_data dm_bio_= prison dm_bufio iptable_filter veth tcp_diag inet_diag mpls_gso act_mpls cl= s_flower cls_bpf sch_ingress ip_set_hash_ip ip_set_hash_net ip_set tcp_bbr = sch_fq tun xt_bpf nf_conntrack nf_defrag_ipv6 nf_defrag_ipv4 fou6 fou ip_tu= nnel ip6_udp_tunnel udp_tunnel ip6_tunnel tunnel6 nvme_fabrics raid0 md_mod= essiv dm_crypt trusted asn1_encoder tee dm_mod dax 8021q garp mrp stp llc = ipmi_ssif amd64_edac kvm_amd kvm irqbypass crc32_pclmul crc32c_intel > > [ 904.196247] [ C33] sha512_ssse3 sha256_ssse3 sha1_ssse3 aesni_i= ntel crypto_simd xhci_pci binfmt_misc acpi_ipmi cryptd ipmi_si nvme rapl ip= mi_devintf i2c_piix4 tiny_power_button bnxt_en xhci_hcd nvme_core ccp i2c_s= mbus ipmi_msghandler button fuse configfs nfnetlink efivarfs ip_tables x_ta= bles bcmcrypt(O) > > [ 904.196281] [ C33] CPU: 33 UID: 0 PID: 0 Comm: swapper/33 Kdump:= loaded Tainted: G O 6.12.34-cloudflare-2025.6.9 #1 > > [ 904.196286] [ C33] Tainted: [O]=3DOOT_MODULE > > [ 904.196287] [ C33] Hardware name: GIGABYTE R162-Z12-CD-G11P5/MZ1= 2-HD4-CD, BIOS M10-sig 02/17/2025 > > [ 904.196290] [ C33] RIP: 0010:io_idle+0x3/0x30 > > [ 904.196298] [ C33] Code: 8b 00 a8 08 75 07 e8 2c e4 ff ff 90 fa = e9 c0 b3 1a 00 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 = 90 89 fa ec <48> 8b 05 96 42 d4 01 a9 00 00 00 80 75 11 80 3d 4a 42 d4 01 0= 0 75 > > [ 904.196301] [ C33] RSP: 0018:ffff9afa88307e70 EFLAGS: 00000093 > > [ 904.196304] [ C33] RAX: 0000000000000000 RBX: ffff8abdf2b5d898 R= CX: 0000000000000040 > > [ 904.196306] [ C33] RDX: 0000000000000814 RSI: ffff8abdf2b5d800 R= DI: 0000000000000814 > > [ 904.196308] [ C33] RBP: 0000000000000002 R08: ffffffffa9dff860 R= 09: 0000000000000007 > > [ 904.196309] [ C33] R10: 000000e65239d580 R11: 071c71c71c71c71c R= 12: ffffffffa9dff860 > > [ 904.196311] [ C33] R13: ffffffffa9dff948 R14: 0000000000000002 R= 15: 0000000000000000 > > [ 904.196313] [ C33] FS: 0000000000000000(0000) GS:ffff8aadcf6800= 00(0000) knlGS:0000000000000000 > > [ 904.196316] [ C33] CS: 0010 DS: 0000 ES: 0000 CR0: 000000008005= 0033 > > [ 904.196318] [ C33] CR2: 00005632ce239000 CR3: 0000003944f72004 C= R4: 0000000000770ef0 > > [ 904.196320] [ C33] PKRU: 55555554 > > [ 904.196322] [ C33] Call Trace: > > [ 904.196324] [ C33] > > [ 904.196326] [ C33] acpi_idle_do_entry+0x22/0x50 > > [ 904.196336] [ C33] acpi_idle_enter+0x7b/0xd0 > > [ 904.196340] [ C33] cpuidle_enter_state+0x79/0x420 > > [ 904.196345] [ C33] cpuidle_enter+0x2d/0x40 > > [ 904.196352] [ C33] do_idle+0x176/0x1c0 > > [ 904.196358] [ C33] cpu_startup_entry+0x29/0x30 > > [ 904.196362] [ C33] start_secondary+0xf7/0x100 > > [ 904.196366] [ C33] common_startup_64+0x13e/0x141 > > [ 904.196374] [ C33] > > [ 904.196377] [ C33] Kernel panic - not syncing: Hard LOCKUP > > [ 904.196379] [ C33] CPU: 33 UID: 0 PID: 0 Comm: swapper/33 Kdump:= loaded Tainted: G O 6.12.34-cloudflare-2025.6.9 #1 > > [ 904.196383] [ C33] Tainted: [O]=3DOOT_MODULE > > [ 904.196384] [ C33] Hardware name: GIGABYTE R162-Z12-CD-G11P5/MZ1= 2-HD4-CD, BIOS M10-sig 02/17/2025 > > [ 904.196385] [ C33] Call Trace: > > [ 904.196387] [ C33] > > [ 904.196389] [ C33] dump_stack_lvl+0x4b/0x70 > > [ 904.196394] [ C33] panic+0x106/0x2c4 > > [ 904.196401] [ C33] nmi_panic.cold+0xc/0xc > > [ 904.196404] [ C33] watchdog_hardlockup_check.cold+0xc6/0xe8 > > [ 904.196409] [ C33] __perf_event_overflow+0x15a/0x450 > > [ 904.196416] [ C33] ? srso_alias_return_thunk+0x5/0xfbef5 > > [ 904.196421] [ C33] x86_pmu_handle_irq+0x18a/0x1c0 > > [ 904.196436] [ C33] ? set_pte_vaddr+0x40/0x50 > > [ 904.196439] [ C33] ? srso_alias_return_thunk+0x5/0xfbef5 > > [ 904.196442] [ C33] ? srso_alias_return_thunk+0x5/0xfbef5 > > [ 904.196445] [ C33] ? native_set_fixmap+0x63/0xb0 > > [ 904.196448] [ C33] ? srso_alias_return_thunk+0x5/0xfbef5 > > [ 904.196451] [ C33] ? ghes_copy_tofrom_phys+0x7a/0x100 > > [ 904.196457] [ C33] ? srso_alias_return_thunk+0x5/0xfbef5 > > [ 904.196460] [ C33] ? __ghes_peek_estatus.isra.0+0x49/0xa0 > > [ 904.196465] [ C33] amd_pmu_handle_irq+0x4b/0xc0 > > [ 904.196469] [ C33] perf_event_nmi_handler+0x2a/0x50 > > [ 904.196473] [ C33] nmi_handle.part.0+0x59/0x110 > > [ 904.196479] [ C33] default_do_nmi+0x127/0x180 > > [ 904.196483] [ C33] exc_nmi+0x103/0x180 > > [ 904.196486] [ C33] end_repeat_nmi+0xf/0x53 > > [ 904.196489] [ C33] RIP: 0010:io_idle+0x3/0x30 > > [ 904.196493] [ C33] Code: 8b 00 a8 08 75 07 e8 2c e4 ff ff 90 fa = e9 c0 b3 1a 00 0f 1f 44 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 = 90 89 fa ec <48> 8b 05 96 42 d4 01 a9 00 00 00 80 75 11 80 3d 4a 42 d4 01 0= 0 75 > > [ 904.196495] [ C33] RSP: 0018:ffff9afa88307e70 EFLAGS: 00000093 > > [ 904.196497] [ C33] RAX: 0000000000000000 RBX: ffff8abdf2b5d898 R= CX: 0000000000000040 > > [ 904.196499] [ C33] RDX: 0000000000000814 RSI: ffff8abdf2b5d800 R= DI: 0000000000000814 > > [ 904.196501] [ C33] RBP: 0000000000000002 R08: ffffffffa9dff860 R= 09: 0000000000000007 > > [ 904.196502] [ C33] R10: 000000e65239d580 R11: 071c71c71c71c71c R= 12: ffffffffa9dff860 > > [ 904.196504] [ C33] R13: ffffffffa9dff948 R14: 0000000000000002 R= 15: 0000000000000000 > > [ 904.196510] [ C33] ? io_idle+0x3/0x30 > > [ 904.196515] [ C33] ? io_idle+0x3/0x30 > > [ 904.196519] [ C33] > > [ 904.196520] [ C33] > > [ 904.196521] [ C33] acpi_idle_do_entry+0x22/0x50 > > [ 904.196526] [ C33] acpi_idle_enter+0x7b/0xd0 > > [ 904.196529] [ C33] cpuidle_enter_state+0x79/0x420 > > [ 904.196535] [ C33] cpuidle_enter+0x2d/0x40 > > [ 904.196539] [ C33] do_idle+0x176/0x1c0 > > [ 904.196544] [ C33] cpu_startup_entry+0x29/0x30 > > [ 904.196548] [ C33] start_secondary+0xf7/0x100 > > [ 904.196552] [ C33] common_startup_64+0x13e/0x141 > > [ 904.196559] [ C33] > > > > Best, Fred