Warning at kernel/sched/core.c:4637 after booting

[terencode]

I observe the following warning happening shortly after booting linux 5.12.11 with CacULE v5.12-r2 (NO_HZ_FULL) :

WARNING: CPU: 0 PID: 227 at kernel/sched/core.c:4637 sched_tick_remote+0x123/0x180
Modules linked in: uas usb_storage iwlmvm nls_iso8859_1 vfat fat mac80211 intel_rapl_msr intel_rapl_common kvm_amd kvm libarc4 snd_hda_codec_realtek iwlwifi snd_hda_codec_generic ledtrig_audio snd_usb_audio crct10dif_pclmul crc32_pclmul snd_hda_intel ghash_clmulni_intel aesni_intel cfg80211 snd_intel_dspcfg snd_hda_codec crypto_simd cryptd igb rapl snd_usbmidi_lib snd_rawmidi snd_seq_device i2c_piix4 snd_hwdep snd_hda_core pcspkr ccp dca zenpower(OE) rfkill rng_core gpio_amdpt gpio_generic pinctrl_amd acpi_cpufreq mac_hid wmi_bmof mxm_wmi vendor_reset(OE) pkcs8_key_parser i2c_dev ledtrig_timer it87(OE) hwmon_vid ee1004 snd_aloop snd_pcm snd_timer snd soundcore v4l2loopback_dc(OE) videodev mc sg crypto_user asus_wmi_sensors(OE) wmi fuse ip_tables x_tables ext4 crc32c_generic crc16 mbcache jbd2 amdgpu crc32c_intel xhci_pci xhci_pci_renesas drm_ttm_helper ttm gpu_sched i2c_algo_bit drm_kms_helper syscopyarea sysfillrect sysimgblt fb_sys_fops cec drm agpgart vfio_pci irqbypass
 vfio_virqfd vfio_iommu_type1 vfio
CPU: 0 PID: 227 Comm: kworker/u64:12 Tainted: G           OE     5.12.11-168-tkg-cacule #1
Hardware name: System manufacturer System Product Name/CROSSHAIR VI HERO, BIOS 7901 07/31/2020
Workqueue: events_unbound sched_tick_remote
RIP: 0010:sched_tick_remote+0x123/0x180
Code: 00 00 41 5d e9 4e b1 fe ff 83 bd 18 0a 00 00 01 76 46 48 8b 85 40 0a 00 00 49 2b 85 20 01 00 00 ba 00 5e d0 b2 48 39 d0 76 90 <0f> 0b eb 8c 0f 0b 5b 5d 41 5c 41 5d c3 89 c2 e9 fd fe ff ff 48 c7
RSP: 0018:ffffac6b80947e68 EFLAGS: 00010082
RAX: fffffffffd9fac54 RBX: 0000000000000008 RCX: ffff8fc28ea00000
RDX: 00000000b2d05e00 RSI: 00000000239f5376 RDI: 0000000000000008
RBP: ffff8fc28ea2c640 R08: 00000000c127f591 R09: 000000000000000f
R10: 000000000000000f R11: fefefefefefefeff R12: ffff8fc28ea31688
R13: ffff8fbf8fc68000 R14: 0000000000000000 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8fc28e800000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fb1a6874000 CR3: 00000001061b2000 CR4: 0000000000350ef0
Call Trace:
 process_one_work+0x217/0x3e0
 worker_thread+0x4d/0x3d0
 ? process_one_work+0x3e0/0x3e0
 kthread+0x134/0x160
 ? kthread_associate_blkcg+0xc0/0xc0
 ret_from_fork+0x22/0x30

[ptr1337]

Maybe a error from linux-tkg project.

https://seafile.ptr1337.dev/d/4046e0b9a4bf41d2abb0/

Here are some Genv3 Kernels precompiled, check if the problem also happens.

[hamadmarri]

Hi @terencode

http://lkml.iu.edu/hypermail/linux/kernel/1804.0/01103.html

If it is the same problem, I think it is related to the mainstream kernel. CacULE has no changes on no_hz_*

Thank you

[terencode]

It's not coming from linux-tkg. I tried your build linux-cacule-5.12.12-1-x86_64.pkg.tar.zst and can still reproduce the warning.
There is no warning when using linux-tkg with NO_HZ_FULL too but using PDS instead of CACULE.

[ptr1337]

which bootloader youre using and which config options are you using there ?

which distro are using ?

your system specs should be also interesting.

[raykzhao]

Hi @terencode @ptr1337 @hamadmarri,

I believe this is the same issue as I previously mentioned here: #23 (reply in thread). Since this warning comes from a check and the computed delta is not actually used anywhere, currently I just comment out this check in order to suppress the warning:

--- a/kernel/sched/core.c	2021-05-07 20:53:26.000000000 +1000
+++ b/kernel/sched/core.c	2021-05-09 20:44:03.476618640 +1000
@@ -4619,14 +4619,14 @@
 
 	update_rq_clock(rq);
 
-	if (!is_idle_task(curr)) {
-		/*
-		 * Make sure the next tick runs within a reasonable
-		 * amount of time.
-		 */
-		delta = rq_clock_task(rq) - curr->se.exec_start;
-		WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
-	}
+	//if (!is_idle_task(curr)) {
+		///*
+		 //* Make sure the next tick runs within a reasonable
+		 //* amount of time.
+		 //*/
+		//delta = rq_clock_task(rq) - curr->se.exec_start;
+		//WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+	//}
 	curr->sched_class->task_tick(rq, curr, 0);
 
 	calc_load_nohz_remote(rq);

[terencode]

which bootloader youre using and which config options are you using there ?

Not sure why the bootloader would matter here but I'm using refind.
When you say "config options" I assume you mean kernel parameters in the context of bootloader?
Here they are : audit=0 root=UUID=a30ceffc-8940-46b1-96b0-952e9642799a rw initrd=amd-ucode.img initrd=initramfs-linux-tkg-cacule.img quiet splash loglevel=3 vt.global_cursor_default=0 rd.systemd.show_status=auto rd.udev.log-priority=3 libahci.ignore_sss=1 scsi_mod.use_blk_mq=1 threadirqs amdgpu.ppfeaturemask=0xffffffff nowatchdog vfio-pci.ids=1002:6610 xhci_hcd.quirks=270336 nohz_full=1-5,7-11

which distro are using ?

ArchLinux

your system specs should be also interesting.

Here are some :

• CPU: ryzen 5 3600
• GPU : vega 56
• motherboard: crosshair VI hero
• RAM: 2x8GB

Hi @terencode @ptr1337 @hamadmarri,

Hey!

I believe this is the same issue as I previously mentioned here: #23 (reply in thread). Since this warning comes from a check and the computed delta is not actually used anywhere, currently I just comment out this check in order to suppress the warning:

Ah dang I searched the thread for someone having a similar issue using CTR+F but forgot that after a thread reaches a certain length, messages are hidden and you need to hit the "view more" button...

I see hamadmarri asked some questions about your input at the end of the thread, maybe it's the occasion to continue here?

[hamadmarri]

Hi @terencode @ptr1337 @hamadmarri,

I believe this is the same issue as I previously mentioned here: #23 (reply in thread). Since this warning comes from a check and the computed delta is not actually used anywhere, currently I just comment out this check in order to suppress the warning:

--- a/kernel/sched/core.c	2021-05-07 20:53:26.000000000 +1000
+++ b/kernel/sched/core.c	2021-05-09 20:44:03.476618640 +1000
@@ -4619,14 +4619,14 @@
 
 	update_rq_clock(rq);
 
-	if (!is_idle_task(curr)) {
-		/*
-		 * Make sure the next tick runs within a reasonable
-		 * amount of time.
-		 */
-		delta = rq_clock_task(rq) - curr->se.exec_start;
-		WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
-	}
+	//if (!is_idle_task(curr)) {
+		///*
+		 //* Make sure the next tick runs within a reasonable
+		 //* amount of time.
+		 //*/
+		//delta = rq_clock_task(rq) - curr->se.exec_start;
+		//WARN_ON_ONCE(delta > (u64)NSEC_PER_SEC * 3);
+	//}
 	curr->sched_class->task_tick(rq, curr, 0);
 
 	calc_load_nohz_remote(rq);

Hi @raykzhao
cc: @terencode @ptr1337

I will add your patch to cacule soon. I was planning to add it that time but I got busy and forgot about it.

Thank you so much