syzbot


WARNING in lookup_slow

Status: upstream: reported C repro on 2023/12/02 22:03
Bug presence: origin:upstream
Labels: missing-backport
[Documentation on labels]
Reported-by: syzbot+06c698fb96b88f7018dc@syzkaller.appspotmail.com
First crash: 950d, last: 4d11h
Fix bisection: the issue occurs on the latest tested release (bisect log)
Crash: WARNING in lookup_slow (log)
Repro: C syz .config
  
Bug presence (3)
Date Name Commit Repro Result
2024/01/17 linux-6.1.y (ToT) fec3b1451d5f C [report] WARNING in lookup_slow
2023/12/03 upstream (ToT) 968f35f4ab1c C [report] WARNING in lookup_slow
2024/01/17 upstream (ToT) 052d534373b7 C Didn't crash
Similar bugs (8)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-5.15 WARNING in lookup_slow (2) -1 1 981d 981d 0/3 auto-obsoleted due to no activity on 2024/02/09 08:58
upstream WARNING in lookup_slow (2) fs -1 8 756d 787d 0/29 auto-obsoleted due to no activity on 2024/09/12 01:16
linux-6.6 WARNING in lookup_slow -1 1 183d 183d 0/2 auto-obsoleted due to no activity on 2026/04/17 12:20
upstream WARNING in lookup_slow (3) fs -1 1 563d 559d 0/29 auto-obsoleted due to no activity on 2025/02/21 12:31
linux-5.15 WARNING in lookup_slow (3) origin:lts-only -1 C error 8 27d 831d 0/3 upstream: reported C repro on 2024/03/30 12:27
upstream WARNING in lookup_slow (4) prio:high fs -1 23 6d05h 409d 0/29 moderation: reported on 2025/05/26 09:57
upstream WARNING in lookup_slow ntfs3 -1 C error inconclusive 34 898d 1298d 0/29 auto-obsoleted due to no activity on 2024/05/02 19:30
linux-5.15 WARNING in lookup_slow -1 1 1141d 1141d 0/3 auto-obsoleted due to no activity on 2023/09/02 18:27
Fix bisection attempts (2)
Created Duration User Patch Repo Result
2024/01/18 17:12 1h55m fix candidate upstream OK (0) job log
2024/01/02 04:25 1h56m bisect fix linux-6.1.y OK (0) job log log

Sample crash report:
------------[ cut here ]------------
DEBUG_RWSEMS_WARN_ON(!is_rwsem_reader_owned(sem)): count = 0x0, magic = 0xffff888068ac4cf0, owner = 0x0, curr 0xffff88802e17da00, list empty
WARNING: CPU: 0 PID: 6933 at kernel/locking/rwsem.c:1345 __up_read+0x628/0x6b0 kernel/locking/rwsem.c:1345
Modules linked in:
CPU: 0 PID: 6933 Comm: syz.0.834 Not tainted syzkaller #0
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 05/09/2026
RIP: 0010:__up_read+0x628/0x6b0 kernel/locking/rwsem.c:1345
Code: 0f 44 d0 48 c7 c7 20 0b 8c 8a 48 c7 c6 c0 0b 8c 8a 48 89 da 48 8b 4c 24 08 4d 89 e0 4d 89 f1 41 52 e8 5c 55 ea ff 48 83 c4 08 <0f> 0b 4c 8b 3c 24 e9 40 fb ff ff 48 c7 c1 68 56 21 8e 80 e1 07 80
RSP: 0018:ffffc9000631faa0 EFLAGS: 00010296
RAX: fadd6d61d7b74500 RBX: 0000000000000000 RCX: ffff88802e17da00
RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000002
RBP: ffffc9000631fb48 R08: ffffc9000631f727 R09: 1ffff92000c63ee4
R10: dffffc0000000000 R11: fffff52000c63ee5 R12: 0000000000000000
R13: 1ffff92000c63f58 R14: ffff88802e17da00 R15: ffff888068ac4d48
FS:  00007f980a7fe6c0(0000) GS:ffff8880b8e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033
CR2: 00007f980a7fdff8 CR3: 000000002535a000 CR4: 00000000003506f0
DR0: 0000000000000000 DR1: 0000000000000000 DR2: 0000000000000000
DR3: 0000000000000000 DR6: 00000000fffe0ff0 DR7: 0000000000000400
Call Trace:
 <TASK>
 inode_unlock_shared include/linux/fs.h:773 [inline]
 lookup_slow+0x5e/0x70 fs/namei.c:1716
 walk_component+0x2ad/0x3e0 fs/namei.c:2006
 lookup_last fs/namei.c:2463 [inline]
 path_lookupat+0x148/0x420 fs/namei.c:2487
 filename_lookup+0x229/0x580 fs/namei.c:2516
 user_path_at_empty+0x3e/0x60 fs/namei.c:2913
 user_path_at include/linux/namei.h:57 [inline]
 do_mount fs/namespace.c:3418 [inline]
 __do_sys_mount fs/namespace.c:3629 [inline]
 __se_sys_mount+0x2a4/0x3d0 fs/namespace.c:3606
 do_syscall_x64 arch/x86/entry/common.c:46 [inline]
 do_syscall_64+0x4c/0xa0 arch/x86/entry/common.c:76
 entry_SYSCALL_64_after_hwframe+0x68/0xd2
RIP: 0033:0x7f980b19de59
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:00007f980a7fe028 EFLAGS: 00000246 ORIG_RAX: 00000000000000a5
RAX: ffffffffffffffda RBX: 00007f980b426090 RCX: 00007f980b19de59
RDX: 0000000000000000 RSI: 0000200000000000 RDI: 0000000000000000
RBP: 00007f980b233e6f R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000800 R11: 0000000000000246 R12: 0000000000000000
R13: 00007f980b426128 R14: 00007f980b426090 R15: 00007ffc04cadce8
 </TASK>

Crashes (10):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/07/05 18:50 linux-6.1.y 090666d3cc90 fcece630 .config console log report syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan WARNING in lookup_slow
2024/04/02 03:15 linux-6.1.y e5cd595e23c1 6baf5069 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
2023/12/02 22:59 linux-6.1.y 6ac30d748bb0 f819d6f7 .config console log report syz C [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
2024/06/15 12:23 linux-6.1.y ae9f2a70d69e f429ab00 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in lookup_slow
2024/05/31 12:15 linux-6.1.y 88690811da69 0c378259 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in lookup_slow
2024/04/08 01:49 linux-6.1.y 347385861c50 ca620dd8 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan WARNING in lookup_slow
2025/08/13 19:42 linux-6.1.y 3594f306da12 22ec1469 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
2025/02/26 12:12 linux-6.1.y 3a8358583626 d34966d1 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
2024/08/22 09:01 linux-6.1.y ee5e09825b81 ca02180f .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
2023/12/02 22:02 linux-6.1.y 6ac30d748bb0 f819d6f7 .config console log report info [disk image] [vmlinux] [kernel image] ci2-linux-6-1-kasan-arm64 WARNING in lookup_slow
* Struck through repros no longer work on HEAD.