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Thu, 29 Jul 2021 05:37:07 -0700 (PDT) MIME-Version: 1.0 References: In-Reply-To: From: Bruno Goncalves Date: Thu, 29 Jul 2021 14:36:56 +0200 Message-ID: Subject: Re: WARNING: CPU: 112 PID: 2041 at kernel/sched/sched.h:1453 To: Dietmar Eggemann Cc: CKI Project , linux-kernel@vger.kernel.org, nathan@kernel.org, Memory Management , linux-arm-kernel@lists.infradead.org Content-Type: text/plain; charset="UTF-8" Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Jul 28, 2021 at 5:55 PM Dietmar Eggemann wrote: > > On 28/07/2021 15:11, Bruno Goncalves wrote: > > Hello, > > > > Since this commit (Commit: 45312bd762d3 - Merge tag 'zonefs-5.14-rc2') > > we started to see the following call trace, it seems to be > > reproducible only on aarch64. > > It should happen on platforms using a slow-switching cpufreq driver. > > Only in this case you have n (depends on nbr of frequency domains) > special-purpose DL threads when using schedutil CPUFreq governor: > > root@juno: ps -eTo comm,pid,pri,class | grep sugov > > sugov:0 132 140 DLN > sugov:1 134 140 DLN > > > > > [ 384.485614] ------------[ cut here ]------------ > > [ 384.490227] rq->clock_update_flags < RQCF_ACT_SKIP > > [ 384.490232] WARNING: CPU: 112 PID: 2041 at > > kernel/sched/sched.h:1453 sub_running_bw.isra.0+0x190/0x1a0 > > [ 384.504312] Modules linked in: mlx5_ib ib_uverbs ib_core rfkill > > sunrpc acpi_ipmi ipmi_ssif mlx5_core mlxfw psample ipmi_devintf > > arm_cmn ipmi_msghandler arm_dsu_pmu cppc_cpufreq acpi_tad vfat fat > > fuse zram ip_tables x_tables xfs crct10dif_ce ghash_ce ast > > i2c_algo_bit drm_vram_helper sbsa_gwdt drm_kms_helper syscopyarea > > sysfillrect sysimgblt fb_sys_fops cec drm_ttm_helper ttm nvme > > nvme_core drm xgene_hwmon aes_neon_bs > > [ 384.541165] CPU: 112 PID: 2041 Comm: sugov:112 Tainted: G W > > 5.14.0-rc1 #1 > > [ 384.549244] Hardware name: WIWYNN Mt.Jade Server System > > B81.030Z1.0007/Mt.Jade Motherboard, BIOS 1.6.20210526 (SCP: > > 1.06.20210526) 2021/05/26 > > [ 384.561922] pstate: 404000c9 (nZcv daIF +PAN -UAO -TCO BTYPE=--) > > [ 384.567918] pc : sub_running_bw.isra.0+0x190/0x1a0 > > [ 384.572698] lr : sub_running_bw.isra.0+0x190/0x1a0 > > [ 384.577477] sp : ffff800024c4bb20 > > [ 384.580779] x29: ffff800024c4bb20 x28: 0000000000000000 x27: ffffb9a9bbe1d200 > > [ 384.587904] x26: 0000000000000074 x25: 0000000000000011 x24: ffffb9a9bdff9000 > > [ 384.595029] x23: ffff07ffb36fcaa0 x22: ffff401ee09b65c0 x21: ffffb9a9bbe1de00 > > [ 384.602153] x20: ffff401ee09a3360 x19: ffff401ee09b6f58 x18: 0000000000000000 > > [ 384.609277] x17: ffff867522f0c000 x16: ffff800010384000 x15: 0000000000000030 > > [ 384.616401] x14: 0000000000000000 x13: 50494b535f544341 x12: 5f46435152203c20 > > [ 384.623526] x11: ffff401ee04b0ea8 x10: ffff401ee021e068 x9 : ffffb9a9bbe4214c > > [ 384.630650] x8 : 0000000000010ea8 x7 : ffff401ee01e0000 x6 : 0000000000017ffd > > [ 384.637774] x5 : ffff401ee09a3490 x4 : 0000000000000001 x3 : ffff867522f0c000 > > [ 384.644898] x2 : ffff401ee09a3498 x1 : ffff07ffb53cc000 x0 : 0000000000000026 > > [ 384.652022] Call trace: > > [ 384.654457] sub_running_bw.isra.0+0x190/0x1a0 > > [ 384.658890] migrate_task_rq_dl+0xf8/0x1e0 > > [ 384.662975] set_task_cpu+0xa8/0x1f0 > > [ 384.666540] try_to_wake_up+0x150/0x3d4 > > [ 384.670365] wake_up_q+0x64/0xc0 > > [ 384.673582] __up_write+0xd0/0x1c0 > > [ 384.676974] up_write+0x4c/0x2b0 > > [ 384.680191] cppc_set_perf+0x120/0x2d0 > > [ 384.683931] cppc_cpufreq_set_target+0xe0/0x1a4 [cppc_cpufreq] > > [ 384.689756] __cpufreq_driver_target+0x74/0x140 > > [ 384.694277] sugov_work+0x64/0x80 > > [ 384.697580] kthread_worker_fn+0xe0/0x230 > > [ 384.701580] kthread+0x138/0x140 > > [ 384.704797] ret_from_fork+0x10/0x18 > > Don't quite get this. > `sugov:112` should be a special DL entity (dl_se->flags & > SCHED_FLAG_SUGOV) so sub_running_bw() should not call __sub_running_bw() > and hence there won't be a call to cpufreq_update_util() which calls > q_clock(rq) -> assert_clock_updated()? > > Can't reproduce it on my Juno (arm64) (slow-switching (scpi-cpufreq > driver)). We seem to be able to reproduce this only on Ampere Altra machines, specifically on mtjade and mtsnow cpus. # cpupower frequency-info analyzing CPU 0: driver: cppc_cpufreq CPUs which run at the same hardware frequency: 0 CPUs which need to have their frequency coordinated by software: 0 maximum transition latency: Cannot determine or is not supported. hardware limits: 1000 MHz - 2.80 GHz available cpufreq governors: conservative ondemand userspace powersave performance schedutil current policy: frequency should be within 2.00 GHz and 2.80 GHz. The governor "schedutil" may decide which speed to use within this range. current CPU frequency: 1.55 GHz (asserted by call to hardware) # ps -eTo comm,pid,pri,class | grep sugov sugov:0 1082 140 DLN sugov:1 1085 140 DLN ... sugov:78 1319 140 DLN sugov:79 1320 140 DLN Bruno >