[syzbot ci] Re: bpf: Add preempt disable for bpf_get_stack

[syzbot ci]

syzbot ci has tested the following series

[v2] bpf: Add preempt disable for bpf_get_stack
https://lore.kernel.org/all/20260206090653.133...@linux.dev
* [PATCH bpf-next v2 1/2] bpf: Add preempt disable for bpf_get_stack
* [PATCH bpf-next v2 2/2] bpf: Add preempt disable for bpf_get_stackid

and found the following issue:
WARNING in preempt_count_sub

Full report is available here:
https://ci.syzbot.org/series/90d08df2-d19d-404f-b9dd-c201605b83a2

***

WARNING in preempt_count_sub

tree: bpf-next
URL: https://kernel.googlesource.com/pub/scm/linux/kernel/git/bpf/bpf-next.git
base: 1ace9bac1ad2bc6a0a70baaa16d22b7e783e88c5
arch: amd64
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
config: https://ci.syzbot.org/builds/64881591-241a-4854-9beb-1f691566835c/config
C repro: https://ci.syzbot.org/findings/98f347c8-b879-4c85-829b-a20ef900e645/c_repro
syz repro: https://ci.syzbot.org/findings/98f347c8-b879-4c85-829b-a20ef900e645/syz_repro

------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(val > preempt_count())
WARNING: kernel/sched/core.c:5751 at preempt_count_sub+0x9e/0x170 kernel/sched/core.c:5751, CPU#0: syz.0.17/5991
Modules linked in:
CPU: 0 UID: 0 PID: 5991 Comm: syz.0.17 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.2-debian-1.16.2-1 04/01/2014
RIP: 0010:preempt_count_sub+0xa5/0x170 kernel/sched/core.c:5751
Code: 05 cf 8f 48 c1 e8 03 0f b6 04 18 84 c0 0f 85 88 00 00 00 83 3d ef 21 3d 0e 00 75 13 48 8d 3d b2 f3 3f 0e 48 c7 c6 a0 fe 8b 8b <67> 48 0f b9 3a 90 eb b8 90 e8 5d ab 03 03 85 c0 74 2f 48 c7 c0 a4
RSP: 0018:ffffc90004437bc8 EFLAGS: 00010246
RAX: 0000000000000000 RBX: dffffc0000000000 RCX: ffff8881746f8000
RDX: 0000000000000000 RSI: ffffffff8b8bfea0 RDI: ffffffff8fd1d770
RBP: ffffc90004437cd0 R08: ffffffff8fcf05a3 R09: 1ffffffff1f9e0b4
R10: dffffc0000000000 R11: fffffbfff1f9e0b5 R12: dffffc0000000000
R13: 1ffff92000886f84 R14: 0000000000000000 R15: 0000000000000000
FS: 000055557d481500(0000) GS:ffff88818e328000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f1f89c706c0 CR3: 00000001742f0000 CR4: 00000000000006f0
Call Trace:
<TASK>
bpf_prog_test_run_raw_tp+0x4b9/0x6c0 net/bpf/test_run.c:794
bpf_prog_test_run+0x2c7/0x340 kernel/bpf/syscall.c:4721
__sys_bpf+0x643/0x950 kernel/bpf/syscall.c:6246
__do_sys_bpf kernel/bpf/syscall.c:6341 [inline]
__se_sys_bpf kernel/bpf/syscall.c:6339 [inline]
__x64_sys_bpf+0x7c/0x90 kernel/bpf/syscall.c:6339
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xe2/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f1f89d9acb9
Code: ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 48 89 f8 48 89 f7 48 89 d6 48 89 ca 4d 89 c2 4d 89 c8 4c 8b 4c 24 08 0f 05 <48> 3d 01 f0 ff ff 73 01 c3 48 c7 c1 e8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007fff9e3fd488 EFLAGS: 00000246 ORIG_RAX: 0000000000000141
RAX: ffffffffffffffda RBX: 00007f1f8a015fa0 RCX: 00007f1f89d9acb9
RDX: 000000000000000c RSI: 0000200000000500 RDI: 000000000000000a
RBP: 00007f1f89e08bf7 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f1f8a015fac R14: 00007f1f8a015fa0 R15: 00007f1f8a015fa0
</TASK>
----------------
Code disassembly (best guess):
0: 05 cf 8f 48 c1 add $0xc1488fcf,%eax
5: e8 03 0f b6 04 call 0x4b60f0d
a: 18 84 c0 0f 85 88 00 sbb %al,0x88850f(%rax,%rax,8)
11: 00 00 add %al,(%rax)
13: 83 3d ef 21 3d 0e 00 cmpl $0x0,0xe3d21ef(%rip) # 0xe3d2209
1a: 75 13 jne 0x2f
1c: 48 8d 3d b2 f3 3f 0e lea 0xe3ff3b2(%rip),%rdi # 0xe3ff3d5
23: 48 c7 c6 a0 fe 8b 8b mov $0xffffffff8b8bfea0,%rsi
* 2a: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2f: 90 nop
30: eb b8 jmp 0xffffffea
32: 90 nop
33: e8 5d ab 03 03 call 0x303ab95
38: 85 c0 test %eax,%eax
3a: 74 2f je 0x6b
3c: 48 rex.W
3d: c7 .byte 0xc7
3e: c0 .byte 0xc0
3f: a4 movsb %ds:(%rsi),%es:(%rdi)


***

If these findings have caused you to resend the series or submit a
separate fix, please add the following tag to your commit message:
Tested-by: syz...@syzkaller.appspotmail.com

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