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WARNING in task_participate_group_stop (2)

Status: upstream: reported C repro on 2018/04/29 17:00
Subsystems: kernel
[Documentation on labels]
Reported-by: syzbot+b109633ea805cac54a61@syzkaller.appspotmail.com
First crash: 2862d, last: 8d00h
▶ ▼ ✨ AI Jobs (4)
ID Workflow Result Correct Bug Created Started Finished Revision Error
ce5302dc-0b2a-43f4-b897-f9e821163895 patching 💥 WARNING in task_participate_group_stop (2) 2026/02/04 12:55 2026/02/04 13:21 2026/02/04 13:25 9b618abc0cd923b36c7a5ebc58a21174112d8f70 reproducer did not crash
e2858942-01eb-4e18-9b85-007e3229bf3b patching 🏃 WARNING in task_participate_group_stop (2) 2026/02/04 11:51 2026/02/04 12:37 a8a5086b62a3e3675c060a37e770833456f40888+
deb01e98-43c4-46e7-80dc-5fd59ac0612b patching 💥 WARNING in task_participate_group_stop (2) 2026/02/04 11:50 2026/02/04 11:50 2026/02/04 11:51 a8a5086b62a3e3675c060a37e770833456f40888+ Basic kernel testing failed: lost connection to test machine
2ba16071-edf4-4bab-a903-d91dc31506fa patching 💥 WARNING in task_participate_group_stop (2) 2026/02/04 11:32 2026/02/04 11:33 2026/02/04 11:43 a8a5086b62a3e3675c060a37e770833456f40888 Basic kernel testing failed: lost connection to test machine
Cause bisection: the issue happens on the oldest tested release (bisect log)
Crash: WARNING in corrupted (log)
Repro: C syz .config
  
Fix bisection: fixed by (bisect log) [merge commit]:
commit c32beba325d8c54d8affa158a0a54643ba87eab4
Author: Olof Johansson <olof@lixom.net>
Date: Thu May 16 06:23:43 2019 +0000

  Merge tag 'mvebu-arm-5.2-1' of git://git.infradead.org/linux-mvebu into arm/late

  
▶ ▼ Discussions (1)
Title Replies (including bot) Last reply
WARNING in task_participate_group_stop (2) 1 (2) 2018/04/30 13:22
▶ ▼ Similar bugs (9)
Kernel Title Rank 🛈 Repro Cause bisect Fix bisect Count Last Reported Patched Status
linux-4.14 WARNING in task_participate_group_stop -1 C inconclusive 8 1257d 2279d 0/1 upstream: reported C repro on 2019/12/02 14:36
android-6-12 WARNING in task_participate_group_stop origin:upstream -1 C 2 8d01h 165d 0/1 premoderation: reported C repro on 2025/09/15 18:43
android-414 WARNING in task_participate_group_stop -1 C 2 2550d 2514d 0/1 public: reported C repro on 2019/04/12 00:01
android-44 WARNING in task_participate_group_stop (2) -1 C 4 2550d 2513d 0/2 public: reported C repro on 2019/04/13 00:00
android-49 WARNING in task_participate_group_stop -1 C 15 2971d 3127d 2/3 fixed on 2018/02/06 12:55
upstream WARNING in task_participate_group_stop -1 C 29 3027d 3042d 4/29 fixed on 2018/02/02 04:39
linux-4.19 WARNING in task_participate_group_stop -1 C error 11 1258d 2279d 0/1 upstream: reported C repro on 2019/12/02 13:46
android-44 WARNING in task_participate_group_stop -1 C 10 2979d 2986d 2/2 fixed on 2018/02/06 10:09
android-49 WARNING in task_participate_group_stop (2) -1 C 11 2279d 2512d 0/3 public: reported C repro on 2019/04/14 00:00
▶ ▼ Last patch testing requests (10)
Created Duration User Patch Repo Result
2026/02/20 06:02 1h02m retest repro linux-next report log
2026/01/18 13:18 1h16m retest repro linux-next report log
2025/12/12 02:49 27m retest repro linux-next OK log
2025/12/12 02:49 27m retest repro linux-next OK log
2025/12/12 02:49 31m retest repro linux-next report log
2025/11/09 06:30 30m retest repro linux-next report log
2025/10/03 01:49 1m retest repro linux-next error
2025/10/03 01:49 1m retest repro linux-next error
2025/10/03 01:49 4m retest repro linux-next error
2025/08/31 03:57 48m retest repro linux-next error

Sample crash report:
process 'memfd:-BN4EyѧS:)' started with executable stack
------------[ cut here ]------------
sig->group_stop_count == 0
WARNING: kernel/signal.c:373 at task_participate_group_stop+0x215/0x2d0 kernel/signal.c:373, CPU#1: memfd:-BN4Ey/6054
Modules linked in:
CPU: 1 UID: 0 PID: 6054 Comm: memfd:-BN4Ey Not tainted syzkaller #0 PREEMPT(full) 
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:task_participate_group_stop+0x215/0x2d0 kernel/signal.c:373
Code: c0 41 89 04 24 b0 01 eb 07 e8 27 c5 3a 00 31 c0 48 83 c4 08 5b 41 5c 41 5d 41 5e 41 5f 5d c3 cc cc cc cc cc e8 0c c5 3a 00 90 <0f> 0b 90 43 0f b6 04 2f 84 c0 0f 85 8b 00 00 00 41 8b 2e e9 4d ff
RSP: 0018:ffffc90003027be0 EFLAGS: 00010093
RAX: ffffffff818b2d84 RBX: 0000000000060013 RCX: ffff888030933c80
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff52000604f80 R12: ffff88801d7bba00
R13: dffffc0000000000 R14: ffff88801d7bbaa8 R15: 1ffff11003af7755
FS:  0000000000000000(0000) GS:ffff888125102000(0000) knlGS:0000000000000000
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000ffc1b20b CR3: 000000005b4ba000 CR4: 00000000003526f0
Call Trace:
 <TASK>
 do_signal_stop+0x3be/0x5c0 kernel/signal.c:2617
 get_signal+0xa8c/0x1330 kernel/signal.c:2881
 arch_do_signal_or_restart+0xbc/0x830 arch/x86/kernel/signal.c:337
 __exit_to_user_mode_loop kernel/entry/common.c:64 [inline]
 exit_to_user_mode_loop+0x86/0x480 kernel/entry/common.c:98
 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:226 [inline]
 syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:256 [inline]
 syscall_exit_to_user_mode include/linux/entry-common.h:325 [inline]
 do_syscall_64+0x32d/0xf80 arch/x86/entry/syscall_64.c:100
 entry_SYSCALL_64_after_hwframe+0x77/0x7f
RIP: 0023:0x33e
Code: Unable to access opcode bytes at 0x314.
RSP: 002b:00000000ffc1b120 EFLAGS: 00000202 ORIG_RAX: 000000000000000b
RAX: 0000000000000000 RBX: 0000000000000000 RCX: 0000000000000000
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: 0000000000000000 R08: 0000000000000000 R09: 0000000000000000
R10: 0000000000000000 R11: 0000000000000000 R12: 0000000000000000
R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000
 </TASK>

Crashes (25):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/20 10:56 linux-next 44982d352c33 17d780d6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in task_participate_group_stop
2025/09/18 03:55 linux-next ae2d20002576 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in task_participate_group_stop
2021/08/13 19:33 linux-next 4b358aabb93a 3fd2ea69 .config console log report syz ci-upstream-linux-next-kasan-gce-root WARNING in task_participate_group_stop
2021/09/01 05:09 upstream 9c849ce86e0f 7eb7e152 .config console log report syz C ci-upstream-kasan-gce-selinux-root WARNING in task_participate_group_stop
2021/05/16 20:05 upstream 63d1cb53e26a f54a5c09 .config console log report syz C ci-upstream-kasan-gce WARNING in task_participate_group_stop
2018/04/28 22:08 upstream a97d8efd9d35 d5a5d045 .config console log report syz C ci-upstream-kasan-gce
2019/03/06 18:53 upstream 3717f613f48d 05cf83bf .config console log report syz C ci-upstream-kasan-gce
2019/03/06 18:52 upstream 3717f613f48d 05cf83bf .config console log report syz C ci-upstream-kasan-gce-root
2020/03/29 01:46 upstream 906c40438bb6 05736b29 .config console log report syz ci-upstream-kasan-gce
2019/12/03 10:35 upstream 596cf45cbf6e ab342da3 .config console log report syz ci-upstream-kasan-gce-root
2019/03/06 19:46 upstream 3717f613f48d 05cf83bf .config console log report syz ci-upstream-kasan-gce-selinux-root
2019/03/06 18:47 upstream 3717f613f48d 05cf83bf .config console log report syz ci-upstream-kasan-gce-smack-root
2018/05/02 13:48 upstream f2125992e7cb d5b114b4 .config console log report syz ci-upstream-kasan-gce-386
2019/12/02 14:55 upstream ceb307474506 f879db37 .config console log report syz ci-upstream-kasan-gce
2019/12/02 15:34 upstream ceb307474506 f879db37 .config console log report syz ci-upstream-kasan-gce-386
2019/03/06 18:46 upstream 3717f613f48d 05cf83bf .config console log report syz ci-upstream-kasan-gce-386
2020/04/21 08:59 linux-next ac935d227366 98a9f9e6 .config console log report syz ci-upstream-linux-next-kasan-gce-root
2021/08/06 20:40 upstream 902e7f373fff f9e341e3 .config console log report syz C ci-upstream-kasan-gce-selinux-root WARNING in task_participate_group_stop
2021/02/12 01:55 upstream 291009f656e8 a5f86b15 .config console log report syz C ci-upstream-kasan-gce WARNING in task_participate_group_stop
2023/04/23 16:09 upstream 622322f53c6d 2b32bd34 .config console log report info [disk image] [vmlinux] [kernel image] ci-upstream-kasan-gce-smack-root WARNING in task_participate_group_stop
2025/09/18 17:54 linux-next ae2d20002576 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in task_participate_group_stop
2025/09/18 11:25 linux-next ae2d20002576 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci-upstream-rust-kasan-gce WARNING in task_participate_group_stop
2018/04/29 02:26 upstream bf8f5de17442 d5a5d045 .config console log report syz C ci-upstream-kasan-gce-root
2020/01/30 16:06 upstream 39bed42de2e7 5ed23f9a .config console log report ci-upstream-kasan-gce
2018/10/07 07:37 upstream c1d84a1b42ef 8b311eaf .config console log report ci-upstream-kasan-gce-selinux-root
* Struck through repros no longer work on HEAD.