[bug] kernel panic when running ublk selftest on next-20250321

[Ming Lei <ming.lei@redhat.com>]

Hello,

When running ublk selftest on today's next tree, the following kernel
panic is triggered immediately:

```
cd tools/testing/selftests/ublk/
make
./test_loop_01.sh
```

And not see this issue on next-0317.


ktest-40 login: [   35.406086] BUG: unable to handle page fault for address: fffffdf1ea10bc88
[   35.407360] #PF: supervisor read access in kernel mode
[   35.408259] #PF: error_code(0x0000) - not-present page
[   35.409138] PGD 0 P4D 0 
[   35.409596] Oops: Oops: 0000 [#1] SMP NOPTI
[   35.410620] CPU: 15 UID: 0 PID: 1661 Comm: kublk Not tainted 6.14.0-rc7_blk_dev-next-20250321+ #149 PREEMPT(full) 
[   35.412617] Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-1.fc39 04/01/2014
[   35.414075] RIP: 0010:kfree+0x6f/0x300
[   35.414780] Code: 80 48 01 d8 0f 82 a1 02 00 00 48 c7 c2 00 00 00 80 48 2b 15 2b af a6 01 48 01 d0 48 c1 e8 0c 481
[   35.417874] RSP: 0018:ffffd0bbc358b880 EFLAGS: 00010282
[   35.418800] RAX: fffffdf1ea10bc80 RBX: fffffc35442f2740 RCX: ffff8d0bcc5e35a0
[   35.420100] RDX: 000072f4c0000000 RSI: ffffffff96a9f61a RDI: fffffc35442f2740
[   35.421372] RBP: ffffd0bbc358b8c8 R08: 0000000000000001 R09: 0000000000000014
[   35.422603] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8d0bd18b60c0
[   35.423887] R13: 0000000000000000 R14: 00000000ffffffff R15: ffff8d0bcc5e2290
[   35.425166] FS:  00007fea81c526c0(0000) GS:ffff8d109219b000(0000) knlGS:0000000000000000
[   35.426568] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   35.427574] CR2: fffffdf1ea10bc88 CR3: 00000001083b6005 CR4: 0000000000772ef0
[   35.428714] PKRU: 55555554
[   35.429171] Call Trace:
[   35.429665]  <TASK>
[   35.430046]  ? __die_body.cold+0x19/0x29
[   35.430734]  ? page_fault_oops+0xc9/0x290
[   35.431442]  ? search_module_extables+0x44/0x60
[   35.432181]  ? kfree+0x6f/0x300
[   35.432707]  ? search_bpf_extables+0x5f/0x80
[   35.433405]  ? exc_page_fault+0x189/0x1a0
[   35.434083]  ? asm_exc_page_fault+0x26/0x30
[   35.434742]  ? io_vec_free+0x1a/0x30
[   35.435375]  ? kfree+0x6f/0x300
[   35.435885]  ? psi_group_change+0x13b/0x310
[   35.436578]  io_vec_free+0x1a/0x30
[   35.437163]  io_req_uring_cleanup+0xa6/0xb0
[   35.437836]  io_uring_cmd_done+0xca/0x1d0
[   35.438498]  io_handle_tw_list+0xe8/0xf0
[   35.439154]  tctx_task_work_run+0x51/0xe0
[   35.439917]  tctx_task_work+0x3a/0x60
[   35.440537]  task_work_run+0x59/0x90
[   35.441150]  io_run_task_work+0x4c/0x110
[   35.441816]  io_cqring_wait+0x36b/0x660
[   35.442503]  ? __pfx_io_wake_function+0x10/0x10
[   35.443259]  __do_sys_io_uring_enter+0x4f1/0x750
[   35.444023]  do_syscall_64+0x82/0x170
[   35.444644]  ? syscall_exit_to_user_mode+0x1d5/0x210
[   35.445939]  ? do_syscall_64+0x8e/0x170
[   35.446997]  ? __memcg_slab_post_alloc_hook+0x1f4/0x370
[   35.448272]  ? __kmalloc_noprof+0x456/0x490
[   35.449295]  ? io_cache_alloc_new+0x19/0x80
[   35.450432]  ? io_cache_alloc_new+0x19/0x80
[   35.451506]  ? io_cache_alloc_new+0x19/0x80
[   35.452602]  ? io_rsrc_node_alloc+0x5f/0x70
[   35.453613]  ? io_sqe_files_register+0x204/0x2f0
[   35.454719]  ? __do_sys_io_uring_register+0x129/0xa70
[   35.455901]  ? syscall_exit_to_user_mode+0x1d5/0x210
[   35.457036]  ? syscall_exit_to_user_mode+0x10/0x210
[   35.458236]  ? do_syscall_64+0x8e/0x170
[   35.459226]  ? handle_mm_fault+0x1b8/0x2c0
[   35.460319]  ? do_user_addr_fault+0x211/0x680
[   35.461399]  ? clear_bhb_loop+0x35/0x90
[   35.462373]  ? clear_bhb_loop+0x35/0x90
[   35.463315]  ? clear_bhb_loop+0x35/0x90
[   35.464281]  entry_SYSCALL_64_after_hwframe+0x76/0x7e
[   35.465474] RIP: 0033:0x7fea8264b6fc
[   35.466422] Code: 0f b6 c0 48 8b 79 20 8b 3f 83 e7 01 44 0f 45 d0 41 83 ca 01 8b b9 cc 00 00 00 45 31 c0 41 b9 081
[   35.470085] RSP: 002b:00007fea81c51dc8 EFLAGS: 00000246 ORIG_RAX: 00000000000001aa
[   35.471641] RAX: ffffffffffffffda RBX: 000000003e33b4a8 RCX: 00007fea8264b6fc
[   35.473077] RDX: 0000000000000001 RSI: 0000000000000001 RDI: 0000000000000000
[   35.474524] RBP: 0000000000000080 R08: 0000000000000000 R09: 0000000000000008
[   35.475925] R10: 0000000000000011 R11: 0000000000000246 R12: 000000003e33b4a8
[   35.477837] R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000020
[   35.479455]  </TASK>
[   35.480262] Modules linked in: ip6table_filter iptable_filter isofs intel_rapl_msr intel_rapl_common kvm_intel vfg
[   35.488958] Dumping ftrace buffer:
[   35.490009]    (ftrace buffer empty)
[   35.491043] CR2: fffffdf1ea10bc88
[   35.491946] ---[ end trace 0000000000000000 ]---
[   35.493618] RIP: 0010:kfree+0x6f/0x300
[   35.494707] Code: 80 48 01 d8 0f 82 a1 02 00 00 48 c7 c2 00 00 00 80 48 2b 15 2b af a6 01 48 01 d0 48 c1 e8 0c 481
[   35.498709] RSP: 0018:ffffd0bbc358b880 EFLAGS: 00010282
[   35.500093] RAX: fffffdf1ea10bc80 RBX: fffffc35442f2740 RCX: ffff8d0bcc5e35a0
[   35.501798] RDX: 000072f4c0000000 RSI: ffffffff96a9f61a RDI: fffffc35442f2740
[   35.503907] RBP: ffffd0bbc358b8c8 R08: 0000000000000001 R09: 0000000000000014
[   35.505605] R10: 0000000000000001 R11: 0000000000000000 R12: ffff8d0bd18b60c0
[   35.507362] R13: 0000000000000000 R14: 00000000ffffffff R15: ffff8d0bcc5e2290
[   35.509073] FS:  00007fea81c526c0(0000) GS:ffff8d109219b000(0000) knlGS:0000000000000000
[   35.511178] CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
[   35.512891] CR2: fffffdf1ea10bc88 CR3: 00000001083b6005 CR4: 0000000000772ef0
[   35.514582] PKRU: 55555554
[   35.515538] Kernel panic - not syncing: Fatal exception
[   35.517350] Dumping ftrace buffer:
[   35.518403]    (ftrace buffer empty)
[   35.519900] Kernel Offset: 0x15000000 from 0xffffffff81000000 (relocation range: 0xffffffff80000000-0xffffffffbff)
[   35.522222] ---[ end Kernel panic - not syncing: Fatal exception ]---



Thanks,
Ming