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WARNING in task_participate_group_stop

Status: premoderation: reported C repro on 2025/09/15 18:43
Bug presence: origin:upstream
[Documentation on labels]
Reported-by: syzbot+4d12e6a4ee1d58207e12@syzkaller.appspotmail.com
First crash: 167d, last: 10d
▶ ▼ Bug presence (2)
Date Name Commit Repro Result
2025/09/18 lts (merge base) d90ecb2b1308 C [report] WARNING in task_participate_group_stop
2025/09/18 upstream (ToT) 8b789f2b7602 C [report] WARNING in task_participate_group_stop
▶ ▼ 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 1259d 2282d 0/1 upstream: reported C repro on 2019/12/02 14:36
upstream WARNING in task_participate_group_stop (2) kernel -1 C inconclusive unreliable 25 10d 2864d 0/29 upstream: reported C repro on 2018/04/29 17:00
android-414 WARNING in task_participate_group_stop -1 C 2 2553d 2516d 0/1 public: reported C repro on 2019/04/12 00:01
android-44 WARNING in task_participate_group_stop (2) -1 C 4 2552d 2515d 0/2 public: reported C repro on 2019/04/13 00:00
android-49 WARNING in task_participate_group_stop -1 C 15 2973d 3130d 2/3 fixed on 2018/02/06 12:55
upstream WARNING in task_participate_group_stop -1 C 29 3030d 3044d 4/29 fixed on 2018/02/02 04:39
linux-4.19 WARNING in task_participate_group_stop -1 C error 11 1261d 2282d 0/1 upstream: reported C repro on 2019/12/02 13:46
android-44 WARNING in task_participate_group_stop -1 C 10 2981d 2988d 2/2 fixed on 2018/02/06 10:09
android-49 WARNING in task_participate_group_stop (2) -1 C 11 2282d 2514d 0/3 public: reported C repro on 2019/04/14 00:00
▶ ▼ Last patch testing requests (3)
Created Duration User Patch Repo Result
2026/02/17 01:44 10m retest repro android16-6.12 report log
2025/12/09 00:38 6m retest repro android16-6.12 error
2025/09/29 21:48 40m retest repro android16-6.12 report log

Sample crash report:
process 'memfd:-BN4EyѧS:)' started with executable stack
------------[ cut here ]------------
WARNING: CPU: 0 PID: 735 at kernel/signal.c:375 task_participate_group_stop+0x242/0x300 kernel/signal.c:375
Modules linked in:
CPU: 0 UID: 0 PID: 735 Comm: memfd:-BN4Ey Not tainted syzkaller #0 73dd41fee924560e78783f72ff837ca22365b77d
Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 02/12/2026
RIP: 0010:task_participate_group_stop+0x242/0x300 kernel/signal.c:375
Code: 74 08 4c 89 f7 e8 2e 0a 8c 00 4d 89 2e f0 83 44 24 fc 00 4c 89 f7 be 15 00 00 00 e8 58 91 10 00 e9 aa fe ff ff e8 ae 2f 34 00 <0f> 0b 42 0f b6 04 2b 84 c0 0f 85 8c 00 00 00 45 8b 3e e9 ee fe ff
RSP: 0018:ffffc90001d6fc28 EFLAGS: 00010093
RAX: ffffffff81536da2 RBX: 1ffff11023bb228e RCX: ffff88811c674c00
RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000000000000
RBP: ffffc90001d6fc58 R08: 0000000000000003 R09: 0000000000000004
R10: dffffc0000000000 R11: fffff520003adf8c R12: ffff88811dd91400
R13: dffffc0000000000 R14: ffff88811dd91470 R15: 0000000000000000
FS:  0000000000000000(0000) GS:ffff8881f6e00000(0000) knlGS:0000000000000000
CS:  0010 DS: 002b ES: 002b CR0: 0000000080050033
CR2: 00000000ff84ae6b CR3: 000000011df0a000 CR4: 00000000003526b0
Call Trace:
 <TASK>
 do_signal_stop+0x63b/0x840 kernel/signal.c:2516
 get_signal+0xab9/0x14e0 kernel/signal.c:2780
 arch_do_signal_or_restart+0xbc/0x760 arch/x86/kernel/signal.c:337
 exit_to_user_mode_loop kernel/entry/common.c:111 [inline]
 exit_to_user_mode_prepare include/linux/entry-common.h:328 [inline]
 __syscall_exit_to_user_mode_work kernel/entry/common.c:207 [inline]
 syscall_exit_to_user_mode+0x57/0xb0 kernel/entry/common.c:218
 do_syscall_64+0x63/0xf0 arch/x86/entry/common.c:84
 entry_SYSCALL_64_after_hwframe+0x76/0x7e
RIP: 0023:0x33e
Code: Unable to access opcode bytes at 0x314.
RSP: 002b:00000000ff84ad90 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>
---[ end trace 0000000000000000 ]---

Crashes (2):
Time Kernel Commit Syzkaller Config Log Report Syz repro C repro VM info Assets (help?) Manager Title
2026/02/20 10:19 android16-6.12 879c70c90804 17d780d6 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in task_participate_group_stop
2025/09/15 18:42 android16-6.12 78993dd6e8f8 e2beed91 .config console log report syz / log C [disk image] [vmlinux] [kernel image] ci2-android-6-12-rust WARNING in task_participate_group_stop
* Struck through repros no longer work on HEAD.