On Thu Oct 20, 2022 at 2:55 PM AEST, Sachin Sant wrote:

While running powerpc kselftests (mm/stress_code_patching.sh)
on a PowerVM LPAR following warning is seen. The test passes.
I can reliably recreate it on a Power9 server, not so easily on
Power10.

# ./stress_code_patching.sh 
Testing for spurious faults when mapping kernel memory...
[  175.289418] ------------[ cut here ]------------
[  175.289434] WARNING: CPU: 11 PID: 5436 at arch/powerpc/kernel/irq_64.c:285 arch_local_irq_restore+0x230/0x260
[  175.289450] Modules linked in: dm_mod(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) nft_chain_nat(E) nf_nat(E) nf_conntrack(E) nf_defrag_ipv6(E) nf_defrag_ipv4(E) bonding(E) tls(E) ip_set(E) rfkill(E) nf_tables(E) libcrc32c(E) nfnetlink(E) sunrpc(E) pseries_rng(E) vmx_crypto(E) ext4(E) mbcache(E) jbd2(E) sd_mod(E) t10_pi(E) crc64_rocksoft(E) crc64(E) sg(E) ibmvscsi(E) scsi_transport_srp(E) ibmveth(E) ipmi_devintf(E) ipmi_msghandler(E) fuse(E)
[  175.289582] CPU: 11 PID: 5436 Comm: stress_code_pat Tainted: G            E      6.1.0-rc1-00025-gaae703b02f92 #1
[  175.289591] Hardware name: IBM,8375-42A POWER9 (raw) 0x4e0202 0xf000005 of:IBM,FW950.50 (VL950_105) hv:phyp pSeries
[  175.289599] NIP:  c00000000003e9a0 LR: c0000000000b16dc CTR: 000000000000a6a4
[  175.289607] REGS: c0000000297b35f0 TRAP: 0700   Tainted: G            E       (6.1.0-rc1-00025-gaae703b02f92)
[  175.289616] MSR:  800000000282b033 <SF,VEC,VSX,EE,FP,ME,IR,DR,RI,LE>  CR: 48222224  XER: 00000000
[  175.289654] CFAR: c00000000003e7f4 IRQMASK: 1 
[  175.289654] GPR00: c0000000000b179c c0000000297b3890 c00000000135e900 0000000000000000 
[  175.289654] GPR04: 0000000000000000 0000201760241794 0000000000000000 4009287a77000005 
[  175.289654] GPR08: 0000000000000000 0000000000008000 c00000000ac27d80 0000000000000040 
[  175.289654] GPR12: 0000000000002000 c00000001ec52700 0000000040000000 0000000101239798 
[  175.289654] GPR16: 0000000101239724 00000001011d8128 0000000101170370 000000010123d568 
[  175.289654] GPR20: 000001002f8f5490 0000000000000001 00000001011eaf18 00007fffc1696ab4 
[  175.289654] GPR24: 00007fffc1696ab0 0000000000000000 c008000000180000 000000004be3bca9 
[  175.289654] GPR28: c000000002a590a0 0000000000000000 0000000000000000 c0000000035010c0 
[  175.289787] NIP [c00000000003e9a0] arch_local_irq_restore+0x230/0x260
[  175.289796] LR [c0000000000b16dc] patch_instruction+0x26c/0x340
[  175.289805] Call Trace:
[  175.289810] [c0000000297b3890] [c000000002a590a0] init_mm+0x0/0x5c0 (unreliable)
[  175.289824] [c0000000297b38c0] [c0000000000b179c] patch_instruction+0x32c/0x340
[  175.289835] [c0000000297b3910] [c00000000007ef40] ftrace_make_call+0x220/0x4b0
[  175.289846] [c0000000297b39a0] [c0000000002e00a8] __ftrace_replace_code+0x138/0x140
[  175.289858] [c0000000297b39f0] [c0000000002e0678] ftrace_replace_code+0xa8/0x140
[  175.289869] [c0000000297b3a40] [c0000000002e095c] ftrace_modify_all_code+0x11c/0x240
[  175.289880] [c0000000297b3a70] [c00000000007f918] arch_ftrace_update_code+0x18/0x30
[  175.289891] [c0000000297b3a90] [c0000000002e0bc8] ftrace_startup_enable+0x68/0xa0
[  175.289902] [c0000000297b3ac0] [c0000000002e6618] ftrace_startup+0xf8/0x1c0
[  175.289913] [c0000000297b3b00] [c0000000002e672c] register_ftrace_function+0x4c/0xc0
[  175.289924] [c0000000297b3b30] [c00000000030c908] function_trace_init+0x88/0x100
[  175.289936] [c0000000297b3b60] [c00000000030079c] tracing_set_tracer+0x2ac/0x540
[  175.289946] [c0000000297b3c00] [c000000000300ad4] tracing_set_trace_write+0xa4/0x110
[  175.289957] [c0000000297b3cc0] [c000000000553a00] vfs_write+0x100/0x460
[  175.289968] [c0000000297b3d80] [c000000000553f3c] ksys_write+0x7c/0x140
[  175.289979] [c0000000297b3dd0] [c000000000035160] system_call_exception+0x140/0x350
[  175.289990] [c0000000297b3e10] [c00000000000c654] system_call_common+0xf4/0x278
[  175.290002] --- interrupt: c00 at 0x7fff83c50c34
[  175.290009] NIP:  00007fff83c50c34 LR: 00007fff83bc7c74 CTR: 0000000000000000
[  175.290016] REGS: c0000000297b3e80 TRAP: 0c00   Tainted: G            E       (6.1.0-rc1-00025-gaae703b02f92)
[  175.290025] MSR:  800000000280f033 <SF,VEC,VSX,EE,PR,FP,ME,IR,DR,RI,LE>  CR: 28222222  XER: 00000000
[  175.290065] IRQMASK: 0 
[  175.290065] GPR00: 0000000000000004 00007fffc1696890 00007fff83d37300 0000000000000001 
[  175.290065] GPR04: 000001002f8f2bb0 0000000000000009 0000000000000010 000000006e6f6974 
[  175.290065] GPR08: 0000000000000000 0000000000000000 0000000000000000 0000000000000000 
[  175.290065] GPR12: 0000000000000000 00007fff83e6ae60 0000000040000000 0000000101239798 
[  175.290065] GPR16: 0000000101239724 00000001011d8128 0000000101170370 000000010123d568 
[  175.290065] GPR20: 000001002f8f5490 0000000000000001 00000001011eaf18 00007fffc1696ab4 
[  175.290065] GPR24: 00007fffc1696ab0 000000010123af94 0000000000000009 000001002f8f2bb0 
[  175.290065] GPR28: 0000000000000009 00007fff83d31798 000001002f8f2bb0 0000000000000009 
[  175.290194] NIP [00007fff83c50c34] 0x7fff83c50c34
[  175.290201] LR [00007fff83bc7c74] 0x7fff83bc7c74
[  175.290208] --- interrupt: c00
[  175.290213] Instruction dump:
[  175.290220] 0fe00000 4bfffff0 60000000 60000000 ebe10028 4bfffa95 4bfffed4 60000000 
[  175.290248] 0fe00000 4bffffd0 60000000 60000000 <0fe00000> 4bffffc0 60000000 60000000 
[  175.290275] ---[ end trace 0000000000000000 ]---
OK: Mapping kernel memory does not cause spurious faults

6.0.0 was good. Git bisect points to following

commit a4cb3651a174366cc85a677da9e3681fbe97fdae
Date:   Thu Oct 13 16:44:18 2022 +1000
    powerpc/64s/interrupt: Fix lost interrupts when returning to soft-masked context

Hm, I think I see the problem indeed with that patch. Just have to try
recreate and verify the fix.

Thanks,
Nick