linux-kernel - Re: [main-line]warning at arch/powerpc/net/bpf_jit

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Message-ID: <c195cf5f-dca6-4d17-9f6a-6ccb69854983@linux.ibm.com>
Date: Tue, 25 Mar 2025 11:05:44 +0530
From: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
To: Hari Bathini <hbathini@...ux.ibm.com>,
        Saket Kumar Bhaskar <skb99@...ux.ibm.com>,
        LKML <linux-kernel@...r.kernel.org>, bpf <bpf@...r.kernel.org>,
        Madhavan Srinivasan <maddy@...ux.ibm.com>
Subject: Re: [main-line]warning at arch/powerpc/net/bpf_jit_comp.c:961


On 24/03/25 12:00 am, Hari Bathini wrote:
> Hi Venkat,
>
> On 20/03/25 3:01 am, Hari Bathini wrote:
>>
>>
>> On 19/03/25 1:06 pm, Hari Bathini wrote:
>>> Hi Venkat,
>>>
>>> Thanks for reporting this.
>>> I am having a hard time reproducing this. Please share the
>>> kernel build config..
>>>
>>
>> Thanks for reporting this and sharing the config file offline.
>> Narrowed down the potential root cause. Will post the fix...
>>
>> - Hari
>>
>>> On 17/03/25 6:21 pm, Venkat Rao Bagalkote wrote:
>>>> Greetings!!!
>>>>
>>>> I am observing below warnings on linux-mainline kernel, while 
>>>> running bpf-sefltests.
>>>>
>>>> These warnings are intermitent, reproduces roughly 6 out of 10 times.
>>>>
>>>>
>>>> Repo: 
>>>> https://git.kernel.org/pub/scm/linux/kernel/git/torvalds/linux.git
>>>>
>>>>
>>>> Tests:
>>>>
>>>> ./test_progs
>>>>
>>>>
>>>> Attached is the log file of summary of tests.
>>>>
>>>>
>>>> Traces:
>>>>
>>>> [  978.200120] ------------[ cut here ]------------
>>>> [  978.200133] WARNING: CPU: 11 PID: 45522 at arch/powerpc/net/ 
>>>> bpf_jit_comp.c:961 __arch_prepare_bpf_trampoline.isra.0+0xdc8/0xfe0
>>>> [  978.200144] Modules linked in: tun(E) bpf_testmod(OE) veth(E) 
>>>> bonding(E) tls(E) nft_fib_inet(E) nft_fib_ipv4(E) nft_fib_ipv6(E) 
>>>> nft_fib(E) nft_reject_inet(E) nf_reject_ipv4(E) nf_reject_ipv6(E) 
>>>> nft_reject(E) nft_ct(E) rfkill(E) nft_chain_nat(E) sunrpc(E) 
>>>> ibmveth(E) pseries_rng(E) vmx_crypto(E) drm(E) dm_multipath(E) 
>>>> dm_mod(E) fuse(E) drm_panel_orientation_quirks(E) zram(E) xfs(E) 
>>>> sd_mod(E) ibmvscsi(E) scsi_transport_srp(E) [last unloaded: 
>>>> bpf_test_modorder_x(OE)]
>>>> [  978.200194] CPU: 11 UID: 0 PID: 45522 Comm: test_progs Tainted: 
>>>> G           OE      6.14.0-rc7-auto #4
>>>> [  978.200202] Tainted: [O]=OOT_MODULE, [E]=UNSIGNED_MODULE
>>>> [  978.200205] Hardware name: IBM,8375-42A POWER9 (architected) 
>>>> 0x4e0202 0xf000005 of:IBM,FW950.A0 (VL950_144) hv:phyp pSeries
>>>> [  978.200210] NIP:  c0000000001e3658 LR: c0000000001e34b0 CTR: 
>>>> 0000000000000006
>>>> [  978.200216] REGS: c00000001c057570 TRAP: 0700   Tainted: G OE 
>>>> (6.14.0-rc7-auto)
>>>> [  978.200221] MSR:  8000000000029033 <SF,EE,ME,IR,DR,RI,LE>  CR: 
>>>> 44844442  XER: 20040169
>>>> [  978.200234] CFAR: c0000000001e34e8 IRQMASK: 0
>>>> [  978.200234] GPR00: c0000000001e34b0 c00000001c057810 
>>>> c000000001d68100 0000000000000000
>>>> [  978.200234] GPR04: c00800000025d640 c00000001c05786c 
>>>> 0000000000000160 0000000000000164
>>>> [  978.200234] GPR08: c000000157b8c164 c000000157b8c16c 
>>>> 000000000000016c 0000000000004000
>>>> [  978.200234] GPR12: 0000000000000001 c00000001ec82b00 
>>>> 0000000000000078 0000000038210110
>>>> [  978.200234] GPR16: 00000000000000a8 00000000eb210098 
>>>> 0000000060638000 00000000e86100c0
>>>> [  978.200234] GPR20: 00000000eb4100a0 0000000000000004 
>>>> 000000002c230000 0000000060000000
>>>> [  978.200234] GPR24: fffffffffffff000 c000000005834428 
>>>> c00800000025d640 0000000000000001
>>>> [  978.200234] GPR28: c000000157b89c00 000000000000026c 
>>>> 0000000000000003 c000000157b8c000
>>>> [  978.200294] NIP [c0000000001e3658] 
>>>> __arch_prepare_bpf_trampoline.isra.0+0xdc8/0xfe0
>>>> [  978.200301] LR [c0000000001e34b0] 
>>>> __arch_prepare_bpf_trampoline.isra.0+0xc20/0xfe0
>>>> [  978.200308] Call Trace:
>>>> [  978.200310] [c00000001c057810] [c0000000001e34b0] 
>>>> __arch_prepare_bpf_trampoline.isra.0+0xc20/0xfe0 (unreliable)
>>>> [  978.200319] [c00000001c057950] [c0000000001e4974] 
>>>> arch_prepare_bpf_trampoline+0x94/0x130
>>>> [  978.200327] [c00000001c0579b0] [c0000000005001ac] 
>>>> bpf_trampoline_update+0x23c/0x660
>>>> [  978.200334] [c00000001c057a90] [c0000000005006dc] 
>>>> __bpf_trampoline_link_prog+0x10c/0x360
>>>> [  978.200341] [c00000001c057ad0] [c000000000500c28] 
>>>> bpf_trampoline_link_cgroup_shim+0x268/0x370
>>>> [  978.200348] [c00000001c057b80] [c00000000053254c] 
>>>> __cgroup_bpf_attach+0x4ec/0x760
>>>> [  978.200355] [c00000001c057c60] [c000000000533dd4] 
>>>> cgroup_bpf_prog_attach+0xa4/0x310
>>>> [  978.200362] [c00000001c057cb0] [c00000000049d1b8] 
>>>> bpf_prog_attach+0x2a8/0x2e0
>>>> [  978.200370] [c00000001c057d00] [c0000000004a7278] 
>>>> __sys_bpf+0x428/0xd20
>>>> [  978.200375] [c00000001c057df0] [c0000000004a7b9c] sys_bpf+0x2c/0x40
>>>> [  978.200381] [c00000001c057e10] [c000000000033078] 
>>>> system_call_exception+0x128/0x310
>>>> [  978.200388] [c00000001c057e50] [c00000000000d05c] 
>>>> system_call_vectored_common+0x15c/0x2ec
>>>> [  978.200396] --- interrupt: 3000 at 0x7fff98ba9f40
>>>> [  978.200405] NIP:  00007fff98ba9f40 LR: 00007fff98ba9f40 CTR: 
>>>> 0000000000000000
>>>> [  978.200410] REGS: c00000001c057e80 TRAP: 3000   Tainted: G OE 
>>>> (6.14.0-rc7-auto)
>>>> [  978.200415] MSR:  800000000280f033 
>>>> <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 48002848 XER: 00000000
>>>> [  978.200431] IRQMASK: 0
>>>> [  978.200431] GPR00: 0000000000000169 00007fffde891b10 
>>>> 00007fff98cb6d00 0000000000000008
>>>> [  978.200431] GPR04: 00007fffde891bf8 0000000000000020 
>>>> 0000000000000001 0000000000000008
>>>> [  978.200431] GPR08: 0000000000000008 0000000000000000 
>>>> 0000000000000000 0000000000000000
>>>> [  978.200431] GPR12: 0000000000000000 00007fff995fe9e0 
>>>> 0000000000000000 0000000000000000
>>>> [  978.200431] GPR16: 0000000000000000 0000000000000000 
>>>> 0000000000000000 0000000000000000
>>>> [  978.200431] GPR20: 0000000000000000 0000000000000000 
>>>> 0000000000000000 00007fff995ef438
>>>> [  978.200431] GPR24: 00000000105ed2f4 00007fff995f0000 
>>>> 00007fffde892998 0000000000000001
>>>> [  978.200431] GPR28: 00007fffde892aa8 00007fffde892988 
>>>> 0000000000000001 00007fffde891b40
>>>> [  978.200487] NIP [00007fff98ba9f40] 0x7fff98ba9f40
>>>> [  978.200491] LR [00007fff98ba9f40] 0x7fff98ba9f40
>>>> [  978.200495] --- interrupt: 3000
>>>> [  978.200498] Code: 7d5f412e 81210060 39290001 792a1788 3ba90040 
>>>> 91210060 7d3f5214 57bd103a e9010030 3908ff00 7c294040 4081fae0 
>>>> <0fe00000> 3ba0fff2 4bfffad4 8281003c
>>>> [  978.200519] ---[ end trace 0000000000000000 ]---
>>>>
>>>> If you happen to fix this, please add below tag.
>>>>
>>>>
>>>> Reported-by: Venkat Rao Bagalkote <venkat88@...ux.ibm.com>
>
> The attached fix is not complete but will be sufficient for this
> test scenario. While I come up with the complete fix for all scenarios,
> can you share your observations applying the change...


Hello Hari,


Applied the patch and ran the test 10 times, I could not see the issue.


Regards,

Venkat.

>
> - Hari