On Fri, Mar 08, 2024 at 03:01:28PM +0100, Marek Szyprowski wrote:

This patch landed in today's linux-next as commit 0499a78369ad ("ARM64: 
Dynamically allocate cpumasks and increase supported CPUs to 512"). 
Unfortunately it triggers the following warning during boot on most of 
my ARM64-based test boards. Here is an example from Odroid-N2 board:

  ------------[ cut here ]------------
  WARNING: CPU: 4 PID: 63 at drivers/opp/core.c:2554 
dev_pm_opp_set_config+0x390/0x710
  Modules linked in: dw_hdmi_i2s_audio meson_gxl smsc onboard_usb_hub(+) 
rtc_pcf8563 panfrost snd_soc_meson_axg_sound_card drm_shmem_helper 
crct10dif_ce dwmac_generic snd_soc_meson_card_utils gpu_sched 
snd_soc_meson_g12a_toacodec snd_soc_meson_g12a_tohdmitx rc_odroid 
snd_soc_meson_codec_glue pwm_meson ao_cec_g12a meson_gxbb_wdt meson_ir 
snd_soc_meson_axg_frddr snd_soc_meson_axg_toddr snd_soc_meson_axg_tdmin 
meson_vdec(C) v4l2_mem2mem videobuf2_dma_contig snd_soc_meson_axg_tdmout 
videobuf2_memops axg_audio videobuf2_v4l2 sclk_div videodev 
reset_meson_audio_arb snd_soc_meson_axg_fifo clk_phase dwmac_meson8b 
stmmac_platform videobuf2_common mdio_mux_meson_g12a meson_drm 
meson_dw_hdmi rtc_meson_vrtc stmmac meson_ddr_pmu_g12 mc dw_hdmi 
drm_display_helper pcs_xpcs snd_soc_meson_t9015 meson_canvas gpio_fan 
display_connector snd_soc_meson_axg_tdm_interface 
snd_soc_simple_amplifier snd_soc_meson_axg_tdm_formatter nvmem_meson_efuse
  hub 1-1:1.0: USB hub found
  CPU: 4 PID: 63 Comm: kworker/u12:5 Tainted: G         C 6.8.0-rc3+ #14677
  Hardware name: Hardkernel ODROID-N2 (DT)
  Workqueue: events_unbound deferred_probe_work_func
  pstate: 80000005 (Nzcv daif -PAN -UAO -TCO -DIT -SSBS BTYPE=--)
  pc : dev_pm_opp_set_config+0x390/0x710
  lr : dev_pm_opp_set_config+0x5c/0x710
  ...
  Call trace:
   dev_pm_opp_set_config+0x390/0x710
   dt_cpufreq_probe+0x268/0x480
   platform_probe+0x68/0xd8
   really_probe+0x148/0x2b4
   __driver_probe_device+0x78/0x12c
   driver_probe_device+0xdc/0x164
   __device_attach_driver+0xb8/0x138
   bus_for_each_drv+0x84/0xe0
   __device_attach+0xa8/0x1b0
   device_initial_probe+0x14/0x20
   bus_probe_device+0xb0/0xb4
   deferred_probe_work_func+0x8c/0xc8
   process_one_work+0x1ec/0x53c
   worker_thread+0x298/0x408
   kthread+0x124/0x128
   ret_from_fork+0x10/0x20
  irq event stamp: 317178
  hardirqs last  enabled at (317177): [<ffff8000801788d4>] 
ktime_get_coarse_real_ts64+0x10c/0x110
  hardirqs last disabled at (317178): [<ffff800081222030>] el1_dbg+0x24/0x8c
  softirqs last  enabled at (315802): [<ffff800080010a60>] 
__do_softirq+0x4a0/0x4e8
  softirqs last disabled at (315793): [<ffff8000800169b0>] 
____do_softirq+0x10/0x1c
  ---[ end trace 0000000000000000 ]---
  cpu cpu2: error -EBUSY: failed to set regulators
  cpufreq-dt: probe of cpufreq-dt failed with error -16

It looks that cpufreq-dt and/or opp drivers needs some adjustments 
related with this change.

That's strange. Is this with defconfig? I wonder whether NR_CPUS being
larger caused the issue with this specific code. Otherwise
CPUMASK_OFFSTACK may not work that well on arm64.

quoted

---


Original post: https://www.spinics.net/lists/linux-mm/msg369701.html
V2: https://lkml.org/lkml/2024/2/7/505


V1->V2

- Keep quotation marks
- Remove whiltespace damage
- Add tested by

V2->V3:
- Add test results
- Rework descriptions


 arch/arm64/Kconfig | 16 +++++++++++++++-
 1 file changed, 15 insertions(+), 1 deletion(-)

diff --git a/arch/arm64/Kconfig b/arch/arm64/Kconfig
index aa7c1d435139..4e767dede47d 100644
--- a/arch/arm64/Kconfig
+++ b/arch/arm64/Kconfig

@@ -1427,7 +1427,21 @@ config SCHED_SMT

 config NR_CPUS
     int "Maximum number of CPUs (2-4096)"
     range 2 4096
-    default "256"
+    default "512"
+
+#
+# Determines the placement of cpumasks.
+#
+# With CPUMASK_OFFSTACK the cpumasks are dynamically allocated.
+# Useful for machines with lots of core because it avoids increasing
+# the size of many of the data structures in the kernel.
+#
+# If this is off then the cpumasks have a static sizes and are
+# embedded within data structures.
+#
+    config CPUMASK_OFFSTACK
+    def_bool y
+    depends on NR_CPUS > 256

 config HOTPLUG_CPU
     bool "Support for hot-pluggable CPUs"

Best regards
-- 
Marek Szyprowski, PhD
Samsung R&D Institute Poland

-- 
Catalin

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