linux-kernel - Re: [syzbot] [block?] general protection fault in rtlock_slowlock

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Message-ID: <6911f97d.a70a0220.22f260.00f4.GAE@google.com>
Date: Mon, 10 Nov 2025 06:41:01 -0800
From: syzbot <syzbot+08df3e4c9b304b37cb04@...kaller.appspotmail.com>
To: eadavis@...com, linux-kernel@...r.kernel.org, 
	syzkaller-bugs@...glegroups.com
Subject: Re: [syzbot] [block?] general protection fault in rtlock_slowlock_locked

Hello,

syzbot has tested the proposed patch but the reproducer is still triggering an issue:
kernel BUG in txLock

BUG at fs/jfs/jfs_txnmgr.c:662 assert(last)
------------[ cut here ]------------
kernel BUG at fs/jfs/jfs_txnmgr.c:662!
Oops: invalid opcode: 0000 [#1] SMP KASAN PTI
CPU: 0 UID: 0 PID: 6791 Comm: syz.1.18 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 10/02/2025
RIP: 0010:txLock+0x1b79/0x1cb0 fs/jfs/jfs_txnmgr.c:662
Code: e9 6a f8 ff ff e8 a7 2b 81 fe 48 c7 c7 e0 48 24 8b 48 c7 c6 d9 44 24 8b ba 96 02 00 00 48 c7 c1 e0 49 24 8b e8 88 aa e9 fd 90 <0f> 0b e8 80 2b 81 fe 48 c7 c7 a0 4a 24 8b e8 74 aa e9 fd 48 c7 c7
RSP: 0018:ffffc90004507780 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0fb1e517ffc2aa00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900045078a8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff520008a0e95 R12: 1ffff920006a1200
R13: ffffc90003509000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f0164d3d6c0(0000) GS:ffff888126df7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f424b06b000 CR3: 0000000022db0000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 diWrite+0x444/0x1f40 fs/jfs/jfs_imap.c:654
 txCommit+0x852/0x5430 fs/jfs/jfs_txnmgr.c:1256
 jfs_mkdir+0x856/0xa70 fs/jfs/namei.c:290
 vfs_mkdir+0x306/0x510 fs/namei.c:4453
 do_mkdirat+0x247/0x590 fs/namei.c:4486
 __do_sys_mkdirat fs/namei.c:4503 [inline]
 __se_sys_mkdirat fs/namei.c:4501 [inline]
 __x64_sys_mkdirat+0x87/0xa0 fs/namei.c:4501
 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: 0033:0x7f016daede17
Code: 73 01 c3 48 c7 c1 a8 ff ff ff f7 d8 64 89 01 48 83 c8 ff c3 66 2e 0f 1f 84 00 00 00 00 00 0f 1f 44 00 00 b8 02 01 00 00 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:00007f0164d3ce68 EFLAGS: 00000246 ORIG_RAX: 0000000000000102
RAX: ffffffffffffffda RBX: 00007f0164d3cef0 RCX: 00007f016daede17
RDX: 00000000000001ff RSI: 0000200000000240 RDI: 00000000ffffff9c
RBP: 0000000000000000 R08: 0000200000000240 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000246 R12: 0000200000000240
R13: 00007f0164d3ceb0 R14: 0000000000000000 R15: 0000000000000000
 </TASK>
Modules linked in:
---[ end trace 0000000000000000 ]---
RIP: 0010:txLock+0x1b79/0x1cb0 fs/jfs/jfs_txnmgr.c:662
Code: e9 6a f8 ff ff e8 a7 2b 81 fe 48 c7 c7 e0 48 24 8b 48 c7 c6 d9 44 24 8b ba 96 02 00 00 48 c7 c1 e0 49 24 8b e8 88 aa e9 fd 90 <0f> 0b e8 80 2b 81 fe 48 c7 c7 a0 4a 24 8b e8 74 aa e9 fd 48 c7 c7
RSP: 0018:ffffc90004507780 EFLAGS: 00010246
RAX: 000000000000002b RBX: 0000000000000000 RCX: 0fb1e517ffc2aa00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc900045078a8 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffff520008a0e95 R12: 1ffff920006a1200
R13: ffffc90003509000 R14: 0000000000000000 R15: 0000000000000000
FS:  00007f0164d3d6c0(0000) GS:ffff888126df7000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f424b06b000 CR3: 0000000022db0000 CR4: 00000000003526f0


Tested on:

commit:         e9a6fb0b Linux 6.18-rc5
git tree:       upstream
console output: https://syzkaller.appspot.com/x/log.txt?x=14226412580000
kernel config:  https://syzkaller.appspot.com/x/.config?x=41ad820f608cb833
dashboard link: https://syzkaller.appspot.com/bug?extid=08df3e4c9b304b37cb04
compiler:       Debian clang version 20.1.8 (++20250708063551+0c9f909b7976-1~exp1~20250708183702.136), Debian LLD 20.1.8
patch:          https://syzkaller.appspot.com/x/patch.diff?x=14cb07cd980000