syzbot


lost connection to test machine

Status: upstream: reported C repro on 2023/03/08 15:21
Bug presence: origin:lts-only
[Documentation on labels]
Reported-by: syzbot+6e407b94010a7183c1bc@syzkaller.appspotmail.com
First crash: 904d, last: 38m
Bug presence (2)
Date Name Commit Repro Result
2025/06/30 linux-5.15.y (ToT) 3dea0e7f549e C [report] possible deadlock in ocfs2_get_system_file_inode
2025/06/30 upstream (ToT) d0b3b7b22dfa C Didn't crash
Similar bugs (23)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
android-44 lost connection to test machine (2) -1 6 2819d never 0/2 closed as invalid on 2017/12/09 08:45
android-5-15 lost connection to test machine origin:lts -1 C 276228 now 1058d 0/2 premoderation: reported C repro on 2022/10/05 10:32
android-44 lost connection to test machine (3) -1 C 259 2801d 2818d 0/2 closed as invalid on 2017/12/27 12:57
linux-4.14 lost connection to test machine -1 56267 932d 2331d 0/1 upstream: reported on 2019/04/11 15:39
android-44 lost connection to test machine (4) -1 C 62294 2094d 2328d 0/2 public: reported C repro on 2019/04/14 00:00
android-49 lost connection to test machine (3) -1 C 109581 2094d 2328d 0/3 public: reported C repro on 2019/04/14 08:51
android-44 lost connection to test machine -1 79 2849d 2849d 0/2 closed as invalid on 2017/11/09 08:47
android-6-1 lost connection to test machine origin:lts -1 C 215999 now 841d 0/2 premoderation: reported C repro on 2023/05/10 12:05
android-6-12 lost connection to test machine origin:downstream -1 C 17590 37m 70d 0/1 premoderation: reported C repro on 2025/06/19 05:52
linux-6.6 lost connection to test machine origin:upstream -1 C 5127 1h08m 72d 0/2 upstream: reported C repro on 2025/06/16 17:10
linux-4.4 lost connection to test machine -1 426 2166d 2326d 0/1 auto-closed as invalid on 2019/12/22 11:26
upstream lost connection to test machine (4) -1 C 1189 2739d 2754d 4/29 fixed on 2018/02/26 20:04
android-5-10 lost connection to test machine -1 C 478881 now 1395d 0/2 upstream: reported C repro on 2021/11/02 11:48
android-414 lost connection to test machine -1 C 23644 2094d 2330d 0/1 public: reported C repro on 2019/04/12 00:01
android-49 lost connection to test machine -1 C 8069 2849d 2849d 0/3 closed as invalid on 2017/11/09 10:06
upstream lost connection to test machine (2) -1 C 15874 2801d 2849d 0/29 closed as invalid on 2017/12/27 12:57
android-54 lost connection to test machine -1 syz 136755 94d 2057d 0/2 upstream: reported syz repro on 2020/01/10 15:22
upstream lost connection to test machine (5) -1 C error 2474073 now 2113d 0/29 moderation: reported C repro on 2019/11/15 12:45
upstream lost connection to test machine (3) -1 C 4251 2761d 2800d 4/29 fixed on 2018/02/04 23:45
upstream lost connection to test machine -1 C 25017 2849d 2849d 0/29 closed as invalid on 2017/11/09 10:06
linux-6.1 lost connection to test machine origin:upstream -1 C unreliable 64212 now 904d 0/3 upstream: reported C repro on 2023/03/08 14:43
android-49 lost connection to test machine (2) -1 C 2946 2801d 2849d 0/3 closed as invalid on 2017/12/27 12:57
linux-4.19 lost connection to test machine -1 30440 934d 2331d 0/1 upstream: reported on 2019/04/10 19:39
Crashes (26994):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2025/06/30 02:52 linux-5.15.y 3dea0e7f549e fc9d8ee5 .config console log syz / log C [disk image] [vmlinux] [kernel image] [mounted in repro (clean fs)] ci2-linux-5-15-kasan lost connection to test machine
2025/06/26 21:30 linux-5.15.y 1c700860e8bc 803ce19b .config console log syz / log C [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 11:06 linux-5.15.y c79648372d02 e12e5ba4 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 09:21 linux-5.15.y c79648372d02 e12e5ba4 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 18:25 linux-5.15.y c79648372d02 e12e5ba4 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 06:37 linux-5.15.y c79648372d02 bf27483f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/23 11:24 linux-5.15.y c79648372d02 bf27483f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/23 08:22 linux-5.15.y c79648372d02 bf27483f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/22 18:44 linux-5.15.y c79648372d02 bf27483f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/22 09:10 linux-5.15.y c79648372d02 bf27483f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/21 20:20 linux-5.15.y c79648372d02 3e79b825 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/18 05:38 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/18 03:50 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/17 09:11 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/16 09:54 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/16 04:10 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/16 01:20 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/15 21:56 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/15 10:01 linux-5.15.y c79648372d02 1804e95e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/14 16:13 linux-5.15.y c79648372d02 5d8c2ac2 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/13 17:37 linux-5.15.y c79648372d02 22ec1469 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/13 09:05 linux-5.15.y c79648372d02 22ec1469 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/13 08:49 linux-5.15.y c79648372d02 22ec1469 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/13 07:12 linux-5.15.y c79648372d02 22ec1469 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/13 01:03 linux-5.15.y c79648372d02 22ec1469 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/11 18:00 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/11 15:39 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/11 14:06 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/11 10:28 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] [mounted in repro] ci2-linux-5-15-kasan lost connection to test machine
2025/08/09 20:51 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/09 18:38 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/09 09:56 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/08 22:03 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/08 16:31 linux-5.15.y c79648372d02 32a0e5ed .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/08 00:45 linux-5.15.y c79648372d02 04cffc22 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/07 21:10 linux-5.15.y c79648372d02 04cffc22 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/07 19:58 linux-5.15.y c79648372d02 04cffc22 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/07 08:46 linux-5.15.y c79648372d02 9a42d6b1 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/07 02:07 linux-5.15.y c79648372d02 9a42d6b1 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/06 16:45 linux-5.15.y c79648372d02 ffe1dd46 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/06 15:02 linux-5.15.y c79648372d02 ffe1dd46 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/06 07:37 linux-5.15.y c79648372d02 ffe1dd46 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/06/13 05:50 linux-5.15.y c61bd26ae81a 2aa5052f .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/30 05:46 linux-5.15.y c61bd26ae81a 34889ee3 .config syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2024/05/30 03:52 linux-5.15.y c61bd26ae81a 34889ee3 .config syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/29 17:55 linux-5.15.y c61bd26ae81a 34889ee3 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2024/05/29 17:32 linux-5.15.y c61bd26ae81a 34889ee3 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/29 14:48 linux-5.15.y c61bd26ae81a 34889ee3 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/28 22:44 linux-5.15.y c61bd26ae81a 34889ee3 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/27 20:21 linux-5.15.y c61bd26ae81a 761766e6 .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/27 05:29 linux-5.15.y c61bd26ae81a a10a183e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/27 01:15 linux-5.15.y c61bd26ae81a a10a183e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/25 03:35 linux-5.15.y 83655231580b a10a183e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/24 06:08 linux-5.15.y 83655231580b 8f98448e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/24 04:11 linux-5.15.y 83655231580b 8f98448e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2024/05/28 15:48 linux-5.15.y c61bd26ae81a f550015e .config console log syz / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 lost connection to test machine
2024/05/26 21:54 linux-5.15.y c61bd26ae81a a10a183e .config console log syz [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 lost connection to test machine
2025/08/28 14:51 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 13:47 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 07:45 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 07:25 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 05:57 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 02:00 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 00:58 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/27 22:55 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 22:45 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 21:21 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 20:20 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 19:18 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 15:42 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 14:40 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 13:36 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 12:22 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 09:18 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/27 08:00 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 05:08 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 04:08 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/27 02:03 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 23:31 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 21:59 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/26 20:52 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/26 18:10 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/26 15:49 linux-5.15.y c79648372d02 e12e5ba4 .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 11:05 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 09:53 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 07:28 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 05:42 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 04:16 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/26 03:40 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/26 02:05 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 23:16 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/25 20:43 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 19:40 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 18:27 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 17:22 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 15:22 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/25 10:46 linux-5.15.y c79648372d02 bf27483f .config console log / log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/25 07:55 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/25 06:31 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
2025/08/25 05:21 linux-5.15.y c79648372d02 bf27483f .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-perf lost connection to test machine
2025/08/28 04:05 linux-5.15.y c79648372d02 e12e5ba4 .config console log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 lost connection to test machine
2025/08/26 19:17 linux-5.15.y c79648372d02 e12e5ba4 .config console log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 lost connection to test machine
2025/08/25 14:08 linux-5.15.y c79648372d02 bf27483f .config console log [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan-arm64 lost connection to test machine
2023/03/08 15:21 linux-5.15.y d9b4a0c83a2d 4fc6d98d .config console log info [disk image] [vmlinux] [kernel image] ci2-linux-5-15-kasan lost connection to test machine
* Struck through repros no longer work on HEAD.