[syzbot] [mm?] general protection fault in __rt_mutex_slowlock_locked

[syzbot]

Hello,

syzbot found the following issue on:

HEAD commit: 4a0c9b339199 Merge tag 'probes-fixes-v6.18-rc4' of git://g..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=136e9114580000
kernel config: https://syzkaller.appspot.com/x/.config?x=41ad820f608cb833
dashboard link: https://syzkaller.appspot.com/bug?extid=60f8f8d9d0a992e59f1a
compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8

Unfortunately, I don't have any reproducer for this issue yet.

Downloadable assets:
disk image: https://storage.googleapis.com/syzbot-assets/2f1bc58f2850/disk-4a0c9b33.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/d4d546567b38/vmlinux-4a0c9b33.xz
kernel image: https://storage.googleapis.com/syzbot-assets/4618744dea2b/bzImage-4a0c9b33.xz

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+60f8f8...@syzkaller.appspotmail.com

loop2: detected capacity change from 0 to 32768
Oops: general protection fault, probably for non-canonical address 0xdffffc00e0000153: 0000 [#1] SMP KASAN PTI
KASAN: probably user-memory-access in range [0x0000000700000a98-0x0000000700000a9f]
CPU: 0 UID: 0 PID: 13777 Comm: syz.2.923 Not tainted syzkaller #0 PREEMPT_{RT,(full)}
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cc cc cc cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc90004b4f2f0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffffffff8ac3ee8e RCX: 8a8d6ce156f8e600
RDX: 0000000000000000 RSI: ffffffff8ac3ee8e RDI: 00000000e0000153
RBP: ffffffff819ba5a3 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100a608c91 R12: 0000000000000000
R13: 0000000700000a98 R14: 0000000700000a98 R15: 0000000000000001
FS: 00007f6cb050e6c0(0000) GS:ffff888126df9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31923ffc CR3: 0000000068aae000 CR4: 00000000003526f0
Call Trace:
<TASK>
__kasan_check_byte+0x12/0x40 mm/kasan/common.c:579
kasan_check_byte include/linux/kasan.h:401 [inline]
lock_acquire+0x8d/0x360 kernel/locking/lockdep.c:5842
__raw_spin_lock include/linux/spinlock_api_smp.h:133 [inline]
_raw_spin_lock+0x2e/0x40 kernel/locking/spinlock.c:154
task_blocks_on_rt_mutex kernel/locking/rtmutex.c:1265 [inline]
__rt_mutex_slowlock kernel/locking/rtmutex.c:1719 [inline]
__rt_mutex_slowlock_locked+0x1223/0x25e0 kernel/locking/rtmutex.c:1760
rt_mutex_slowlock+0xb5/0x160 kernel/locking/rtmutex.c:1800
__rt_mutex_lock kernel/locking/rtmutex.c:1815 [inline]
rwbase_write_lock+0x14f/0x750 kernel/locking/rwbase_rt.c:244
i_mmap_lock_write include/linux/fs.h:548 [inline]
vma_link_file mm/vma.c:1781 [inline]
__mmap_new_vma mm/vma.c:2499 [inline]
__mmap_region mm/vma.c:2670 [inline]
mmap_region+0x1bf4/0x20f0 mm/vma.c:2740
do_mmap+0xc23/0x10c0 mm/mmap.c:558
vm_mmap_pgoff+0x2a9/0x4d0 mm/util.c:581
ksys_mmap_pgoff+0x4e9/0x720 mm/mmap.c:604
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7f6cb22af6c9
Code: ff ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 40 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 a8 ff ff ff f7 d8 64 89 01 48
RSP: 002b:00007f6cb050e038 EFLAGS: 00000246 ORIG_RAX: 0000000000000009
RAX: ffffffffffffffda RBX: 00007f6cb2505fa0 RCX: 00007f6cb22af6c9
RDX: 00000000027ffff7 RSI: 0000000000600000 RDI: 0000200000000000
RBP: 00007f6cb2331f91 R08: 0000000000000005 R09: 0000000000000000
R10: 0000000004012011 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f6cb2506038 R14: 00007f6cb2505fa0 R15: 00007ffebcf391b8
</TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:kasan_byte_accessible+0x12/0x30 mm/kasan/generic.c:210
Code: 0f 1f 84 00 00 00 00 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 0f 1f 40 d6 48 c1 ef 03 48 b8 00 00 00 00 00 fc ff df <0f> b6 04 07 3c 08 0f 92 c0 c3 cc cc cc cc cc 66 66 66 66 66 66 2e
RSP: 0018:ffffc90004b4f2f0 EFLAGS: 00010006
RAX: dffffc0000000000 RBX: ffffffff8ac3ee8e RCX: 8a8d6ce156f8e600
RDX: 0000000000000000 RSI: ffffffff8ac3ee8e RDI: 00000000e0000153
RBP: ffffffff819ba5a3 R08: 0000000000000001 R09: 0000000000000000
R10: dffffc0000000000 R11: ffffed100a608c91 R12: 0000000000000000
R13: 0000000700000a98 R14: 0000000700000a98 R15: 0000000000000001
FS: 00007f6cb050e6c0(0000) GS:ffff888126df9000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 0000001b31923ffc CR3: 0000000068aae000 CR4: 00000000003526f0
----------------
Code disassembly (best guess):
0: 0f 1f 84 00 00 00 00 nopl 0x0(%rax,%rax,1)
7: 00
8: 90 nop
9: 90 nop
a: 90 nop
b: 90 nop
c: 90 nop
d: 90 nop
e: 90 nop
f: 90 nop
10: 90 nop
11: 90 nop
12: 90 nop
13: 90 nop
14: 90 nop
15: 90 nop
16: 90 nop
17: 90 nop
18: 0f 1f 40 d6 nopl -0x2a(%rax)
1c: 48 c1 ef 03 shr $0x3,%rdi
20: 48 b8 00 00 00 00 00 movabs $0xdffffc0000000000,%rax
27: fc ff df
* 2a: 0f b6 04 07 movzbl (%rdi,%rax,1),%eax <-- trapping instruction
2e: 3c 08 cmp $0x8,%al
30: 0f 92 c0 setb %al
33: c3 ret
34: cc int3
35: cc int3
36: cc int3
37: cc int3
38: cc int3
39: 66 data16
3a: 66 data16
3b: 66 data16
3c: 66 data16
3d: 66 data16
3e: 66 data16
3f: 2e cs


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