syzbot


WARNING in do_new_mount (6)

Status: moderation: reported on 2026/02/18 14:16
Subsystems: fs
[Documentation on labels]
Reported-by: syzbot+aa9301d3b66961eb2421@syzkaller.appspotmail.com
First crash: 67d, last: 8h13m
✨ AI Jobs (1)
ID Workflow Result Correct Bug Created Started Finished Revision Error
58385d5e-6dc3-4633-9afa-009a6e06e4da repro WARNING in do_new_mount (6) 2026/03/07 03:20 2026/03/07 03:20 2026/03/07 03:29 31e9c887f7dc24e04b3ca70d0d54fc34141844b0
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in do_new_mount -1 2 975d 993d 0/3 auto-obsoleted due to no activity on 2023/11/29 20:19
linux-6.1 WARNING in do_new_mount (2) -1 1 138d 138d 0/3 auto-obsoleted due to no activity on 2026/03/15 04:54
upstream WARNING in do_new_mount fs -1 4 987d 1006d 0/29 auto-obsoleted due to no activity on 2023/11/07 02:18
upstream WARNING in do_new_mount (5) fs -1 1 311d 307d 0/29 auto-obsoleted due to no activity on 2025/09/14 00:27
upstream WARNING in do_new_mount (3) fs -1 1 475d 471d 0/29 auto-obsoleted due to no activity on 2025/03/03 15:54
linux-6.1 WARNING in do_new_mount -1 4 645d 748d 0/3 auto-obsoleted due to no activity on 2024/10/24 11:22
upstream WARNING in do_new_mount (2) fs -1 22 591d 745d 0/29 auto-obsoleted due to no activity on 2024/12/07 21:46
upstream WARNING in do_new_mount (4) fs -1 2 403d 404d 0/29 auto-obsoleted due to no activity on 2025/06/13 20:52

Sample crash report:
------------[ cut here ]------------
DEBUG_LOCKS_WARN_ON(rt_mutex_owner(lock) != current)
WARNING: kernel/locking/rtmutex_common.h:193 at debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline], CPU#0: syz.0.644/11047
WARNING: kernel/locking/rtmutex_common.h:193 at rt_mutex_slowunlock+0x6d9/0x8b0 kernel/locking/rtmutex.c:1428, CPU#0: syz.0.644/11047
Modules linked in:
CPU: 0 UID: 0 PID: 11047 Comm: syz.0.644 Not tainted syzkaller #0 PREEMPT_{RT,(full)} 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026
RIP: 0010:debug_rt_mutex_unlock kernel/locking/rtmutex_common.h:193 [inline]
RIP: 0010:rt_mutex_slowunlock+0x6e0/0x8b0 kernel/locking/rtmutex.c:1428
Code: 8b 8f 48 c1 e8 03 42 0f b6 04 20 84 c0 0f 85 c0 01 00 00 83 3d 74 58 5d 04 00 75 13 48 8d 3d 87 67 60 04 48 c7 c6 20 f2 4c 8b <67> 48 0f b9 3a 90 e9 2a fa ff ff 90 0f 0b 90 e9 4c fe ff ff be 02
RSP: 0018:ffffc900042b7bc0 EFLAGS: 00010046
RAX: 0000000000000000 RBX: ffff888050bf8b38 RCX: 0000000000080000
RDX: ffffc90012f99000 RSI: ffffffff8b4cf220 RDI: ffffffff8f8ef130
RBP: ffffc900042b7cb0 R08: 0000000000000000 R09: 0000000000000000
R10: dffffc0000000000 R11: fffffbfff1f17c43 R12: dffffc0000000000
R13: 1ffff92000856f80 R14: 0000000000000246 R15: ffff888050bf8ae8
FS:  00007fcb9bc8c6c0(0000) GS:ffff8881260fb000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007fcb9bc8bff8 CR3: 000000005cb4a000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 inode_unlock include/linux/fs.h:1039 [inline]
 __unlock_mount fs/namespace.c:2803 [inline]
 unlock_mount fs/namespace.c:2813 [inline]
 do_new_mount_fc fs/namespace.c:3781 [inline]
 do_new_mount+0x7c6/0xd30 fs/namespace.c:3834
 do_mount fs/namespace.c:4167 [inline]
 __do_sys_mount fs/namespace.c:4383 [inline]
 __se_sys_mount+0x31d/0x420 fs/namespace.c:4360
 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline]
 do_syscall_64+0x15f/0xf80 arch/x86/entry/syscall_64.c:94
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0033:0x7fcb9da7c819
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:00007fcb9bc8c028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007fcb9dcf6180 RCX: 00007fcb9da7c819
RDX: 00002000000000c0 RSI: 0000200000000180 RDI: 0000000000000000
RBP: 00007fcb9db12c91 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000001214040 R11: 0000000000000246 R12: 0000000000000000
R13: 00007fcb9dcf6218 R14: 00007fcb9dcf6180 R15: 00007ffe951d24c8
 </TASK>
----------------
Code disassembly (best guess):
   0:	8b 8f 48 c1 e8 03    	mov    0x3e8c148(%rdi),%ecx
   6:	42 0f b6 04 20       	movzbl (%rax,%r12,1),%eax
   b:	84 c0                	test   %al,%al
   d:	0f 85 c0 01 00 00    	jne    0x1d3
  13:	83 3d 74 58 5d 04 00 	cmpl   $0x0,0x45d5874(%rip)        # 0x45d588e
  1a:	75 13                	jne    0x2f
  1c:	48 8d 3d 87 67 60 04 	lea    0x4606787(%rip),%rdi        # 0x46067aa
  23:	48 c7 c6 20 f2 4c 8b 	mov    $0xffffffff8b4cf220,%rsi
* 2a:	67 48 0f b9 3a       	ud1    (%edx),%rdi <-- trapping instruction
  2f:	90                   	nop
  30:	e9 2a fa ff ff       	jmp    0xfffffa5f
  35:	90                   	nop
  36:	0f 0b                	ud2
  38:	90                   	nop
  39:	e9 4c fe ff ff       	jmp    0xfffffe8a
  3e:	be                   	.byte 0xbe
  3f:	02                   	.byte 0x2

Crashes (5):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/04/22 16:18 upstream 6596a02b2078 4595e353 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in do_new_mount
2026/03/07 13:07 upstream 651690480a96 5cb44a80 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in do_new_mount
2026/02/20 08:09 upstream 8bf22c33e7a1 17d780d6 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in do_new_mount
2026/02/14 14:05 upstream c22e26bd0906 1e62d198 .config console log report info [disk image] [vmlinux] [kernel image] ci2-upstream-fs WARNING in do_new_mount
2026/02/25 16:13 upstream 7dff99b35460 c162cde9 .config console log report [disk image (non-bootable)] [vmlinux] [kernel image] ci-snapshot-upstream-root WARNING in do_new_mount
* Struck through repros no longer work on HEAD.