linux-kernel - Re: [BUG 6.18.2] Null Pointer Exception in Fair Scheduler

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Message-ID: <e5cba37b-2bb5-46fb-b414-5cc6b2e894cf@candelatech.com>
Date: Tue, 6 Jan 2026 10:56:49 -0800
From: "Dylan E." <dylan.eskew@...delatech.com>
To: stable@...r.kernel.org, linux-kernel@...r.kernel.org,
 linux-wireless@...r.kernel.org
Cc: gregkh@...uxfoundation.org, sashal@...nel.org, jjohnson@...nel.org
Subject: Re: [BUG 6.18.2] Null Pointer Exception in Fair Scheduler

Hello again,

On 6.18.3, I'm still seeing the scheduler NPE pop-up, though this one 
happened at shutdown. Looks to be an identical location to the previous 
stack trace.

---
BUG: kernel NULL pointer dereference, address: 0000000000000051
#PF: supervisor read access in kernel mode
#PF: error_code(0x0000) - not-present page
PGD 0 P4D 0
Oops: Oops: 0000 [#1] SMP
CPU: 0 UID: 0 PID: 336 Comm: (udev-worker) Not tainted 6.18.3 #39 
PREEMPT(full)
Hardware name: Default string Default string/SKYBAY, BIOS 5.12 02/21/2023
RIP: 0010:pick_task_fair+0x57/0x160
Code: 66 90 66 90 48 8b 5d 50 48 85 db 74 10 48 8b 73 70 48 89 ef e8 3a 
74 ff ff 85 c0 75 71 be 01 00 00 00 48 89 ef e8 29 a5 ff ff <80> 78 51 
00 48 89 c3 0f 85 80 00 00 00 48 85 c0 0f 84 87 00 00 00
RSP: 0018:ffffc9000091bca0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000c00
RDX: fffffa1b1b2acc00 RSI: 0000000000001000 RDI: 0000000000000400
RBP: ffff8881255ef000 R08: 0000000000000400 R09: 0000000000000002
R10: 00000000000003ae R11: ffff88812d2cc200 R12: ffff88845dc2cd00
R13: 0000000000000000 R14: ffff88845dc2cd80 R15: ffffffff827c71e0
FS:  00007fed68640980(0000) GS:ffff8884da723000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000051 CR3: 00000001244dd006 CR4: 00000000003706f0
Call Trace:
  <TASK>
  pick_next_task_fair+0x1d/0x3d0
  __schedule+0x1ee/0x10c0
  ? sock_def_readable+0x3e/0xb0
  ? sock_poll+0x4d/0xd0
  schedule+0x23/0xc0
  schedule_hrtimeout_range_clock+0xf4/0x100
  do_epoll_wait+0x481/0x4b0
  ? ep_destroy_wakeup_source+0x20/0x20
  __x64_sys_epoll_wait+0x5a/0xf0
  ? syscall_trace_enter+0x8d/0x1a0
  do_syscall_64+0x50/0x3a0
  entry_SYSCALL_64_after_hwframe+0x4b/0x53
RIP: 0033:0x7fed69033ea7
Code: 0c 00 f7 d8 64 89 02 b8 ff ff ff ff eb be 0f 1f 44 00 00 f3 0f 1e 
fa 80 3d c5 a4 0c 00 00 41 89 ca 74 10 b8 e8 00 00 00 0f 05 <48> 3d 00 
f0 ff ff 77 51 c3 55 48 89 e5 48 83 ec 20 89 55 f8 48 89
RSP: 002b:00007ffd7c3b5508 EFLAGS: 00000202 ORIG_RAX: 00000000000000e8
RAX: ffffffffffffffda RBX: 0000000000000006 RCX: 00007fed69033ea7
RDX: 0000000000000006 RSI: 0000558994c733e0 RDI: 0000000000000003
RBP: 00007ffd7c3b5620 R08: 0000558994c42010 R09: 0000000000000003
R10: 00000000ffffffff R11: 0000000000000202 R12: 0000558994c733e0
R13: 0000000000000002 R14: 0000558994c73060 R15: ffffffffffffffff
  </TASK>
Modules linked in: i915 drm_buddy intel_gtt drm_client_lib 
drm_display_helper drm_kms_helper cec rc_core ttm agpgart ixgbe igb mdio 
i2c_algo_bit libie_fwlog drm dca hwmon intel_oc_wdt i2c_core mei_wdt 
video wmi
CR2: 0000000000000051
---[ end trace 0000000000000000 ]---
RIP: 0010:pick_task_fair+0x57/0x160
Code: 66 90 66 90 48 8b 5d 50 48 85 db 74 10 48 8b 73 70 48 89 ef e8 3a 
74 ff ff 85 c0 75 71 be 01 00 00 00 48 89 ef e8 29 a5 ff ff <80> 78 51 
00 48 89 c3 0f 85 80 00 00 00 48 85 c0 0f 84 87 00 00 00
RSP: 0018:ffffc9000091bca0 EFLAGS: 00010082
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000c00
RDX: fffffa1b1b2acc00 RSI: 0000000000001000 RDI: 0000000000000400
RBP: ffff8881255ef000 R08: 0000000000000400 R09: 0000000000000002
R10: 00000000000003ae R11: ffff88812d2cc200 R12: ffff88845dc2cd00
R13: 0000000000000000 R14: ffff88845dc2cd80 R15: ffffffff827c71e0
FS:  00007fed68640980(0000) GS:ffff8884da723000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000000000000051 CR3: 00000001244dd006 CR4: 00000000003706f0
Kernel panic - not syncing: Fatal exception
Shutting down cpus with NMI
Kernel Offset: disabled
Rebooting in 30 seconds..
---

Let me know if I can provide anymore information!

-- Dylan