When I tried to test patches applied to v5.15-rc3, I hit this bug (and
hence can not test my code), on 32 bit x86.

------------[ cut here ]------------
kernel BUG at drivers/gpu/drm/i915/i915_sw_fence.c:245!
invalid opcode: 0000 [#1] SMP PTI
CPU: 3 PID: 1 Comm: swapper/0 Not tainted 5.14.0-rc1-test+ #456
Hardware name: MSI MS-7823/CSM-H87M-G43 (MS-7823), BIOS V1.6 02/22/2014
EIP: __i915_sw_fence_init+0x15/0x38
Code: 2b 3d 58 98 88 c1 74 05 e8 60 d9 58 00 8d 65 f4 5b 5e 5f 5d c3 3e
8d 74 26 00 55 89 e5 56 89 d6 53 85 d2 74 05 f6 c2 03 74 02 <0f> 0b 89
ca 8b 4d 08 89 c3 e8 48 94 ab ff 89 73 34 c7 43 38 01 00
EAX: c2508260 EBX: c2508000 ECX: c143de1e EDX: c09dfadd
ESI: c09dfadd EDI: c45e7200 EBP: c26c9c68 ESP: c26c9c60
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010202
CR0: 80050033 CR2: 00000000 CR3: 019e2000 CR4: 001506f0
Call Trace:
 intel_context_init+0x112/0x145
 intel_context_create+0x29/0x37
 intel_ring_submission_setup+0x3cb/0x5a8
 ? kfree+0x135/0x1c6
 ? wa_init_finish+0x32/0x59
 ? wa_init_finish+0x4f/0x59
 ? intel_engine_init_ctx_wa+0x39a/0x3b3
 intel_engines_init+0x2dd/0x4d0
 ? gen6_bsd_submit_request+0x97/0x97
 intel_gt_init+0x122/0x20d
 i915_gem_init+0x80/0xef
 i915_driver_probe+0x880/0xa90
 ? i915_pci_remove+0x27/0x27
 i915_pci_probe+0xdd/0xf6
 ? __pm_runtime_resume+0x63/0x6b
 ? i915_pci_remove+0x27/0x27
 pci_device_probe+0xbc/0x11e
 really_probe+0x13e/0x328
 __driver_probe_device+0x140/0x176
 driver_probe_device+0x1f/0x71
 __driver_attach+0xf6/0x109
 ? __device_attach_driver+0xbd/0xbd
 bus_for_each_dev+0x5b/0x88
 driver_attach+0x19/0x1b
 ? __device_attach_driver+0xbd/0xbd
 bus_add_driver+0xf2/0x199
 driver_register+0x8c/0xbe
 __pci_register_driver+0x5b/0x60
 i915_register_pci_driver+0x19/0x1b
 i915_init+0x15/0x67
 ? radeon_module_init+0x6a/0x6a
 do_one_initcall+0xce/0x21c
 ? rcu_read_lock_sched_held+0x35/0x6d
 ? trace_initcall_level+0x5f/0x99
 kernel_init_freeable+0x1fb/0x247
 ? rest_init+0x129/0x129
 kernel_init+0x17/0xfd
 ret_from_fork+0x1c/0x28
Modules linked in:
---[ end trace 791dc89810d853da ]---
EIP: __i915_sw_fence_init+0x15/0x38
Code: 2b 3d 58 98 88 c1 74 05 e8 60 d9 58 00 8d 65 f4 5b 5e 5f 5d c3 3e
8d 74 26 00 55 89 e5 56 89 d6 53 85 d2 74 05 f6 c2 03 74 02 <0f> 0b 89
ca 8b 4d 08 89 c3 e8 48 94 ab ff 89 73 34 c7 43 38 01 00
EAX: c2508260 EBX: c2508000 ECX: c143de1e EDX: c09dfadd
ESI: c09dfadd EDI: c45e7200 EBP: c26c9c68 ESP: c26c9c60
DS: 007b ES: 007b FS: 00d8 GS: 0000 SS: 0068 EFLAGS: 00010202
CR0: 80050033 CR2: 00000000 CR3: 019e2000 CR4: 001506f0
Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b
Kernel Offset: disabled
---[ end Kernel panic - not syncing: Attempted to kill init! exitcode=0x0000000b ]---

Attached is the dmesg and the config.

I bisected it down to this commit:

3ffe82d701a4 ("drm/i915/xehp: handle new steering options")

-- Steve