[syzbot] [exfat?] [gfs2?] WARNING in filename_symlinkat

syzbot
2026-03-05T06:39:26Z

Hello,

syzbot found the following issue on:

HEAD commit: ecc64d2dc9ff Merge tag 'sysctl-7.00-fixes-rc3' of git://gi..
git tree: upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=1754b5aa580000
kernel config: https://syzkaller.appspot.com/x/.config?x=c5c49ee0942d1cdb
dashboard link: https://syzkaller.appspot.com/bug?extid=2ed46b6b748df855347f
compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8
syz repro: https://syzkaller.appspot.com/x/repro.syz?x=123dbe4a580000
C reproducer: https://syzkaller.appspot.com/x/repro.c?x=15c99b5a580000

Downloadable assets:
disk image (non-bootable): https://storage.googleapis.com/syzbot-assets/d900f083ada3/non_bootable_disk-ecc64d2d.raw.xz
vmlinux: https://storage.googleapis.com/syzbot-assets/86a2ecaacd1b/vmlinux-ecc64d2d.xz
kernel image: https://storage.googleapis.com/syzbot-assets/b1dad86775e5/bzImage-ecc64d2d.xz
mounted in repro: https://storage.googleapis.com/syzbot-assets/1d38e5a93707/mount_4.gz
fsck result: OK (log: https://syzkaller.appspot.com/x/fsck.log?x=17c57006580000)

IMPORTANT: if you fix the issue, please add the following tag to the commit:
Reported-by: syzbot+2ed46b6b748df855347f@syzkaller.appspotmail.com

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DEBUG_RWSEMS_WARN_ON((rwsem_owner(sem) != current) && !rwsem_test_oflags(sem, RWSEM_NONSPINNABLE)): count = 0x0, magic = 0xffff8880460da1f8, owner = 0x0, curr 0xffff8880371624c0, list empty
WARNING: kernel/locking/rwsem.c:1381 at __up_write kernel/locking/rwsem.c:1380 [inline], CPU#0: syz.0.31/5575
WARNING: kernel/locking/rwsem.c:1381 at up_write+0x2d6/0x410 kernel/locking/rwsem.c:1643, CPU#0: syz.0.31/5575
Modules linked in:
CPU: 0 UID: 0 PID: 5575 Comm: syz.0.31 Not tainted syzkaller #0 PREEMPT(full)
Hardware name: QEMU Standard PC (Q35 + ICH9, 2009), BIOS 1.16.3-debian-1.16.3-2 04/01/2014
RIP: 0010:__up_write kernel/locking/rwsem.c:1380 [inline]
RIP: 0010:up_write+0x388/0x410 kernel/locking/rwsem.c:1643
Code: cc 8b 49 c7 c2 80 eb cc 8b 4c 0f 44 d0 48 8b 7c 24 08 48 c7 c6 e0 ed cc 8b 48 8b 14 24 4c 89 f1 4d 89 e0 4c 8b 4c 24 10 41 52 <67> 48 0f b9 3a 48 83 c4 08 e8 5a 83 0b 03 e9 67 fd ff ff 48 c7 c1
RSP: 0018:ffffc9000298fd80 EFLAGS: 00010246
RAX: ffffffff8bcceb60 RBX: ffff8880460da1f8 RCX: ffff8880460da1f8
RDX: 0000000000000000 RSI: ffffffff8bccede0 RDI: ffffffff901501f0
RBP: ffff8880460da250 R08: 0000000000000000 R09: ffff8880371624c0
R10: ffffffff8bcceb60 R11: ffffed1008c1b441 R12: 0000000000000000
R13: dffffc0000000000 R14: ffff8880460da1f8 R15: 1ffff11008c1b440
FS: 00007fbd46c406c0(0000) GS:ffff88808ca58000(0000) knlGS:0000000000000000
CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fbd45de9e80 CR3: 00000000412ea000 CR4: 0000000000352ef0
Call Trace:
<TASK>
inode_unlock include/linux/fs.h:1038 [inline]
end_dirop fs/namei.c:2947 [inline]
end_creating include/linux/namei.h:126 [inline]
end_creating_path fs/namei.c:4962 [inline]
filename_symlinkat+0x222/0x410 fs/namei.c:5642
__do_sys_symlinkat fs/namei.c:5660 [inline]
__se_sys_symlinkat+0x4e/0x2b0 fs/namei.c:5655
do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94
entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fbd45d9c799
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:00007fbd46c40028 EFLAGS: 00000246 ORIG_RAX: 000000000000010a
RAX: ffffffffffffffda RBX: 00007fbd46016090 RCX: 00007fbd45d9c799
RDX: 00002000000003c0 RSI: 0000000000000007 RDI: 0000200000000240
RBP: 00007fbd45e32bd9 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fbd46016128 R14: 00007fbd46016090 R15: 00007ffcbe33eb58
</TASK>
----------------
Code disassembly (best guess), 2 bytes skipped:
0: 49 c7 c2 80 eb cc 8b mov $0xffffffff8bcceb80,%r10
7: 4c 0f 44 d0 cmove %rax,%r10
b: 48 8b 7c 24 08 mov 0x8(%rsp),%rdi
10: 48 c7 c6 e0 ed cc 8b mov $0xffffffff8bccede0,%rsi
17: 48 8b 14 24 mov (%rsp),%rdx
1b: 4c 89 f1 mov %r14,%rcx
1e: 4d 89 e0 mov %r12,%r8
21: 4c 8b 4c 24 10 mov 0x10(%rsp),%r9
26: 41 52 push %r10
* 28: 67 48 0f b9 3a ud1 (%edx),%rdi <-- trapping instruction
2d: 48 83 c4 08 add $0x8,%rsp
31: e8 5a 83 0b 03 call 0x30b8390
36: e9 67 fd ff ff jmp 0xfffffda2
3b: 48 rex.W
3c: c7 .byte 0xc7
3d: c1 .byte 0xc1

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