Public bug reported:

[Impact]
On system with cores > 200, printk during HMAT parsing can create soft
lockup:
[   35.769351] watchdog: BUG: soft lockup - CPU#2 stuck for 22s! [swapper/0:1]
[   35.769354] Modules linked in:
[   35.769358] CPU: 2 PID: 1 Comm: swapper/0 Not tainted 6.8.0-1009-nvidia-64k 
#9~22.04.1-Ubuntu
[   35.769360] Hardware name: NVIDIA PG548-C00/P4975, BIOS 02.02.02 20240729
[   35.769362] pstate: 81001009 (Nzcv daif -PAN -UAO -TCO +DIT +SSBS BTYPE=--)
[   35.769364] pc : console_flush_all+0x1f0/0x3f0
[   35.769375] lr : console_flush_all+0x1e8/0x3f0
[   35.769376] sp : ffff800081b2f870
[   35.769377] x29: ffff800081b2f870 x28: ffffc06104152a10 x27: ffffc06103390008
[   35.769378] x26: 0000000000000001 x25: ffffc06103da8a98 x24: 0000000000000000
[   35.769380] x23: 0000000000000000 x22: ffff800081b2f990 x21: ffff800081b2f98f
[   35.769381] x20: ffffc06104307160 x19: 0000000000000001 x18: 0000000000000000
[   35.769382] x17: 0000000000000000 x16: 0000000000000000 x15: 6977646e61422073
[   35.769384] x14: 0000000000000000 x13: 732f424d20303a5d x12: 39322d39325b7465
[   35.769385] x11: 677261542d726f74 x10: 616974696e492020 x9 : ffffc06100bf35c8
[   35.769386] x8 : 0000000000000000 x7 : 0000000000000000 x6 : 0000000000000000
[   35.769387] x5 : 0000000000000000 x4 : 0000000000000000 x3 : 0000000000000000
[   35.769389] x2 : 0000000000000000 x1 : 0000000000000000 x0 : 0000000000000000
[   35.769391] Call trace:
[   35.769393]  console_flush_all+0x1f0/0x3f0
[   35.769395]  console_unlock+0x70/0x1f8
[   35.769396]  vprintk_emit+0x2e4/0x4b8
[   35.769398]  vprintk_default+0x40/0x80
[   35.769399]  vprintk+0x98/0x150
[   35.769400]  _printk+0x64/0xc0
[   35.769405]  hmat_parse_locality.constprop.0+0x1f4/0x740
[   35.769416]  hmat_parse_subtable+0x58/0xf0
[   35.769418]  acpi_parse_entries_array+0x1fc/0x360
[   35.769426]  acpi_table_parse_entries_array+0xa4/0x170
[   35.769431]  acpi_table_parse_entries+0x4c/0xa0
[   35.769433]  hmat_init+0x14c/0x440
[   35.769434]  do_one_initcall+0x4c/0x368
[   35.769439]  do_initcalls+0x134/0x2c0
[   35.769442]  kernel_init_freeable+0x128/0x2b0
[   35.769443]  kernel_init+0x38/0x240
[   35.769451]  ret_from_fork+0x10/0x20
[   35.959318] acpi/hmat:   Initiator-Target[29-30]:0 MB/s
[   35.964658] acpi/hmat:   Initiator-Target[29-31]:0 MB/s
[   35.969997] acpi/hmat:   Initiator-Target[29-32]:0 MB/s
[   35.975335] acpi/hmat:   Initiator-Target[29-33]:0 MB/s

[Fix]
The information isn't that useful, lower the message level to pr_debug()
to avoid the issue.

[Test]
Boot up the system and check dmesg.
With the patch applied, no more HMAT spam can be found in kernel
message.

[Where problems could occur]
There can be some obscure race conditions be exposed by booting the
kernel faster.

** Affects: linux (Ubuntu)
     Importance: Undecided
         Status: Confirmed

** Changed in: linux (Ubuntu)
       Status: New => Confirmed

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https://bugs.launchpad.net/bugs/2090982

Title:
  Prevent soft lockup on boot up

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