Re: [RFC PATCH v4 01/28] sched: Cache aware load-balancing

Re: [RFC PATCH v4 01/28] sched: Cache aware load-balancing

[kernel test robot]

Hello,

kernel test robot noticed "Oops:general_protection_fault,probably_for_non-canonical_address#:#[##]SMP_KASAN" on:

commit: 2ae6ef14daceb295598846a328dd65fde6b16c99 ("[RFC PATCH v4 01/28] sched: Cache aware load-balancing")
url: https://github.com/intel-lab-lkp/linux/commits/Chen-Yu/sched-Cache-aware-load-balancing/20250809-131716
base: v6.16
patch link: https://lore.kernel.org/all/9157186cf9e3fd541f62c637579ff736b3704c51.1754712565.git.tim.c.chen@linux.intel.com/
patch subject: [RFC PATCH v4 01/28] sched: Cache aware load-balancing

in testcase: boot

config: x86_64-randconfig-103-20250810
compiler: gcc-12
test machine: qemu-system-x86_64 -enable-kvm -cpu SandyBridge -smp 2 -m 16G

(please refer to attached dmesg/kmsg for entire log/backtrace)


+----------------------------------------------------------------------------------+-------+------------+
|                                                                                  | v6.16 | 2ae6ef14da |
+----------------------------------------------------------------------------------+-------+------------+
| Oops:general_protection_fault,probably_for_non-canonical_address#:#[##]SMP_KASAN | 0     | 5          |
| KASAN:null-ptr-deref_in_range[#-#]                                               | 0     | 5          |
| RIP:_find_next_bit                                                               | 0     | 5          |
| Kernel_panic-not_syncing:Fatal_exception                                         | 0     | 5          |
+----------------------------------------------------------------------------------+-------+------------+


If you fix the issue in a separate patch/commit (i.e. not just a new version of
the same patch/commit), kindly add following tags
| Reported-by: kernel test robot <oliver.sang@intel.com>
| Closes: https://lore.kernel.org/oe-lkp/202508111054.58c525c-lkp@intel.com


[   18.108061][    T1] usbcore: registered new interface driver i2c-diolan-u2c
[   18.111512][   T36] input: AT Translated Set 2 keyboard as /devices/platform/i8042/serio0/input/input0
[   18.113593][    T1] Driver for 1-wire Dallas network protocol.
[   18.119966][    T1] f71882fg: Not a Fintek device
[   18.120517][    T1] f71882fg: Not a Fintek device
[   18.142462][   T63] Oops: general protection fault, probably for non-canonical address 0xdffffc0000000012: 0000 [#1] SMP KASAN
[   18.144289][   T63] KASAN: null-ptr-deref in range [0x0000000000000090-0x0000000000000097]
[   18.145594][   T63] CPU: 0 UID: 0 PID: 63 Comm: modprobe Not tainted 6.16.0-00001-g2ae6ef14dace #1 PREEMPT(none)
[   18.146207][   T63] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
[ 18.146207][ T63] RIP: 0010:_find_next_bit (kbuild/src/consumer/lib/find_bit.c:156 (discriminator 2)) 
[ 18.146207][ T63] Code: 48 89 d3 48 83 c8 ff 83 e2 3f 49 89 fe 48 c1 eb 06 c4 62 e9 f7 e8 b8 ff ff 37 00 4c 8d 3c df 48 c1 e0 2a 4c 89 fa 48 c1 ea 03 <80> 3c 02 00 74 08 4c 89 ff e8 cc 76 52 ff 49 8b 07 4c 21 e8 49 bd
All code
========
   0:	48 89 d3             	mov    %rdx,%rbx
   3:	48 83 c8 ff          	or     $0xffffffffffffffff,%rax
   7:	83 e2 3f             	and    $0x3f,%edx
   a:	49 89 fe             	mov    %rdi,%r14
   d:	48 c1 eb 06          	shr    $0x6,%rbx
  11:	c4 62 e9 f7 e8       	shlx   %rdx,%rax,%r13
  16:	b8 ff ff 37 00       	mov    $0x37ffff,%eax
  1b:	4c 8d 3c df          	lea    (%rdi,%rbx,8),%r15
  1f:	48 c1 e0 2a          	shl    $0x2a,%rax
  23:	4c 89 fa             	mov    %r15,%rdx
  26:	48 c1 ea 03          	shr    $0x3,%rdx
  2a:*	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)		<-- trapping instruction
  2e:	74 08                	je     0x38
  30:	4c 89 ff             	mov    %r15,%rdi
  33:	e8 cc 76 52 ff       	call   0xffffffffff527704
  38:	49 8b 07             	mov    (%r15),%rax
  3b:	4c 21 e8             	and    %r13,%rax
  3e:	49                   	rex.WB
  3f:	bd                   	.byte 0xbd

Code starting with the faulting instruction
===========================================
   0:	80 3c 02 00          	cmpb   $0x0,(%rdx,%rax,1)
   4:	74 08                	je     0xe
   6:	4c 89 ff             	mov    %r15,%rdi
   9:	e8 cc 76 52 ff       	call   0xffffffffff5276da
   e:	49 8b 07             	mov    (%r15),%rax
  11:	4c 21 e8             	and    %r13,%rax
  14:	49                   	rex.WB
  15:	bd                   	.byte 0xbd
[   18.146207][   T63] RSP: 0000:ffffc900001f7d28 EFLAGS: 00010206
[   18.146207][   T63] RAX: dffffc0000000000 RBX: 0000000000000000 RCX: fffffbfff0bdd81a
[   18.146207][   T63] RDX: 0000000000000012 RSI: 0000000000000002 RDI: 0000000000000090
[   18.146207][   T63] RBP: ffffc900001f7d50 R08: 0000000000000000 R09: 0000000000000003
[   18.146207][   T63] R10: ffffffff8145362f R11: ffffed103099ffd5 R12: 0000000000000002
[   18.146207][   T63] R13: ffffffffffffffff R14: 0000000000000090 R15: 0000000000000090
[   18.146207][   T63] FS:  0000000000000000(0000) GS:ffff888428798000(0000) knlGS:0000000000000000
[   18.146207][   T63] CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
[   18.146207][   T63] CR2: 00000000f7fc18c8 CR3: 0000000185368000 CR4: 00000000000406b0
[   18.146207][   T63] Call Trace:
[   18.146207][   T63]  <TASK>
[ 18.146207][ T63] task_cache_work (kbuild/src/consumer/include/linux/find.h:71 (discriminator 2) kbuild/src/consumer/kernel/sched/fair.c:1325 (discriminator 2)) 
[ 18.146207][ T63] ? _raw_spin_unlock_irq (kbuild/src/consumer/arch/x86/include/asm/paravirt.h:671 kbuild/src/consumer/include/linux/spinlock_api_smp.h:159 kbuild/src/consumer/kernel/locking/spinlock.c:202) 
[ 18.146207][ T63] ? __pfx_task_cache_work (kbuild/src/consumer/kernel/sched/fair.c:1299) 
[ 18.146207][ T63] ? __this_cpu_preempt_check (kbuild/src/consumer/lib/smp_processor_id.c:67) 


The kernel config and materials to reproduce are available at:
https://download.01.org/0day-ci/archive/20250811/202508111054.58c525c-lkp@intel.com



-- 
0-DAY CI Kernel Test Service
https://github.com/intel/lkp-tests/wiki

Re: [RFC PATCH v4 01/28] sched: Cache aware load-balancing

[Chen, Yu C]

Hi,

On 8/12/2025 9:30 AM, kernel test robot wrote:
> [ 18.146207][ T63] RIP: 0010:_find_next_bit (kbuild/src/consumer/lib/find_bit.c:156 (discriminator 2))
> [ 18.146207][ T63] task_cache_work (kbuild/src/consumer/include/linux/find.h:71 (discriminator 2)
> kbuild/src/consumer/kernel/sched/fair.c:1325 (discriminator 2))

This should have been fixed in the second patch:
02/28 ("sched: Several fixes for cache aware scheduling")that the LLC 
sched domain could be NULL and we should skip the
NULL LLC sched domain.

It might be more applicable to test with the whole patch set.
As this is a RFC version and we will create a formal one with
the fixes integrated into the 01/28 patch, after the issues
have been addressed.

thanks,
Chenyu