Hi Steve, On Wed, Apr 29, 2020 at 05:05:09PM +0800, kernel test robot wrote: > > kern :warn : [ 886.763510] WARNING: CPU: 70 PID: 22584 at > kernel/trace/ring_buffer.c:4067 ring_buffer_iter_peek+0x13c/0x1d0 > kern :warn : [ 886.776216] Modules linked in: test_firmware intel_rapl_msr > intel_rapl_common skx_edac nfit libnvdimm btrfs x86_pkg_temp_thermal > intel_powerclamp blake2b_generic xor zstd_decompress zstd_compress coretemp > ast kvm_intel kvm raid6_pq drm_vram_helper drm_ttm_helper libcrc32c irqbypass > ttm crct10dif_pclmul crc32_pclmul drm_kms_helper snd_pcm crc32c_intel > ghash_clmulni_intel ahci snd_timer syscopyarea libahci aesni_intel ipmi_ssif > sysfillrect snd crypto_simd sysimgblt cryptd nvme fb_sys_fops mei_me > soundcore ipmi_si glue_helper pcspkr drm nvme_core ioatdma ipmi_devintf > t10_pi libata mei i2c_i801 joydev lpc_ich dca ipmi_msghandler wmi acpi_pad > acpi_power_meter ip_tables > kern :warn : [ 886.838112] CPU: 70 PID: 22584 Comm: cat Not tainted > 5.6.0-rc4-00017-g06e0a548bad0f #1 > kern :warn : [ 886.846573] RIP: 0010:ring_buffer_iter_peek+0x13c/0x1d0 > kern :warn : [ 886.852355] Code: 41 5e 41 5f c3 83 38 1d 0f 85 98 00 00 00 > 48 89 df e8 78 cb ff ff e9 32 ff ff ff 80 3c 24 00 75 c8 49 8b 44 24 10 f0 ff > 40 08 <0f> 0b 4c 89 f6 4c 89 ef e8 37 8c 8f 00 48 83 c4 08 31 c0 5b 5d 41 > kern :warn : [ 886.872239] RSP: 0018:ffffc900213e7d78 EFLAGS: 00010002 > kern :warn : [ 886.878030] RAX: ffff889883ea7740 RBX: ffff88a3fbd93720 > RCX: ffff88a42101b700 > kern :warn : [ 886.885731] RDX: ffff88a415c02e00 RSI: ffff88a42101b440 > RDI: ffff88a3fbd93720 > kern :warn : [ 886.893432] RBP: 0000000000000000 R08: 000000ce959ae6ab > R09: ffff88a42101bb80 > kern :warn : [ 886.901129] R10: ffff88a3e99e2300 R11: 0000000000000178 > R12: ffff88a415c02e00 > kern :warn : [ 886.908831] R13: ffff88a415c02e18 R14: 0000000000000296 > R15: ffffc900213e7df8 > kern :warn : [ 886.916521] FS: 00007f12d51d2640(0000) > GS:ffff88a44f780000(0000) knlGS:0000000000000000 > kern :warn : [ 886.925179] CS: 0010 DS: 0000 ES: 0000 CR0: > 0000000080050033 > kern :warn : [ 886.931495] CR2: 00007f12d4e36000 CR3: 00000023e901e006 > CR4: 00000000007606e0 > kern :warn : [ 886.939194] DR0: 0000000000000000 DR1: 0000000000000000 > DR2: 0000000000000000 > kern :warn : [ 886.946896] DR3: 0000000000000000 DR6: 00000000fffe0ff0 > DR7: 0000000000000400 > kern :warn : [ 886.954588] PKRU: 55555554 > kern :warn : [ 886.957858] Call Trace: > kern :warn : [ 886.960866] peek_next_entry+0x22/0x70 > kern :warn : [ 886.965165] __find_next_entry+0xaf/0x180 > kern :warn : [ 886.969714] trace_find_next_entry_inc+0x1e/0x80 > kern :warn : [ 886.974863] s_next+0x49/0x70 > kern :warn : [ 886.978355] seq_read+0x23f/0x400 > kern :warn : [ 886.982193] vfs_read+0x9b/0x160 > kern :warn : [ 886.985937] ksys_read+0xa1/0xe0 > kern :warn : [ 886.989677] do_syscall_64+0x5b/0x1f0 > kern :warn : [ 886.993853] entry_SYSCALL_64_after_hwframe+0x44/0xa9 > kern :warn : [ 886.999408] RIP: 0033:0x7f12d50f559e > kern :warn : [ 887.003479] Code: c0 e9 c6 fe ff ff 50 48 8d 3d 36 fc 09 00 > e8 e9 e7 01 00 66 0f 1f 84 00 00 00 00 00 64 8b 04 25 18 00 00 00 85 c0 75 14 > 0f 05 <48> 3d 00 f0 ff ff 77 5a c3 66 0f 1f 84 00 00 00 00 00 48 83 ec 28 > kern :warn : [ 887.023260] RSP: 002b:00007ffdab31acd8 EFLAGS: 00000246 > ORIG_RAX: 0000000000000000 > kern :warn : [ 887.031350] RAX: ffffffffffffffda RBX: 0000000000020000 > RCX: 00007f12d50f559e > kern :warn : [ 887.039006] RDX: 0000000000020000 RSI: 00007f12d4e36000 > RDI: 0000000000000005 > kern :warn : [ 887.046657] RBP: 00007f12d4e36000 R08: 00007f12d4e35010 > R09: 0000000000000000 > kern :warn : [ 887.054305] R10: fffffffffffffc4d R11: 0000000000000246 > R12: 00007f12d4e36000 > kern :warn : [ 887.061958] R13: 0000000000000005 R14: 0000000000020000 > R15: 0000000000000f93 > kern :warn : [ 887.069608] ---[ end trace 507492ef8332a5b4 ]--- >
Did you had a chance to look into this? I can easily reproduce this both on x86 and s390 by doing: cd /sys/kernel/tracing cat /dev/zero >/dev/null & # generate some load echo function >current_tracer # wait a few seconds to fill the buffer cat trace Usually it will print the warn after a few seconds. I haven't digged through all the ring buffer code yet, so i thought i might ask whether you have an idea what's going on. Thanks Sven