From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo1-f77.google.com (mail-oo1-f77.google.com [209.85.161.77]) (using TLSv1.2 with cipher ECDHE-RSA-AES128-GCM-SHA256 (128/128 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 5EAAC3803DA for ; Fri, 3 Apr 2026 17:50:26 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.77 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775238627; cv=none; b=dwj3cr64KOnrVn5oV1yOuF4lT513IlKLS1w9gJYJwkkub2WgH6i6o6mKFF8uFWAgjNTDRYDUMWzOchT7dJ7hK5a6XMFp5IibJogjYXzEyJ2nnBulM4Yd9t2fCvrsDWYkVBZtCnsvKlGnkZhZyamG/btflC01Rc2l82Mjyo5ry9k= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1775238627; c=relaxed/simple; bh=doi71RKRhlYNeG2BEPfuYmWIkh+Yx4p6/qxdq/wLtT8=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; 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006d021491bc7-68222108070mr1351552eaf.65.1775238625228; Fri, 03 Apr 2026 10:50:25 -0700 (PDT) Date: Fri, 03 Apr 2026 10:50:25 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <69cffde1.050a0220.182279.0016.GAE@google.com> Subject: [syzbot] [kernel?] INFO: rcu detected stall in kill From: syzbot To: anna-maria@linutronix.de, frederic@kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com, tglx@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 9147566d8016 Merge tag 'sched_ext-for-7.0-rc6-fixes' of gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=151c1516580000 kernel config: https://syzkaller.appspot.com/x/.config?x=6754c86e8d9e4c91 dashboard link: https://syzkaller.appspot.com/bug?extid=9b95da55ba5146a60734 compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=111973d6580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=12070dda580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c0b15aadfaef/disk-9147566d.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/9df2af7be859/vmlinux-9147566d.xz kernel image: https://storage.googleapis.com/syzbot-assets/87eba4cf352e/bzImage-9147566d.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+9b95da55ba5146a60734@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P5969/1:b..l rcu: (detected by 1, t=10502 jiffies, g=14521, q=2117 ncpus=2) task:syz-executor state:R running task stack:22432 pid:5969 tgid:5969 ppid:5967 task_flags:0x400140 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6911 preempt_schedule_irq+0x4d/0xa0 kernel/sched/core.c:7238 irqentry_exit+0x599/0x620 kernel/entry/common.c:239 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:697 RIP: 0010:lock_release+0x2d7/0x3d0 kernel/locking/lockdep.c:5893 Code: 16 7b 11 00 00 00 00 eb b5 e8 45 73 0d 0a f7 c3 00 02 00 00 74 b9 65 48 8b 05 c5 d0 7a 11 48 3b 44 24 28 75 44 fb 48 83 c4 30 <5b> 41 5c 41 5d 41 5e 41 5f 5d e9 95 81 6e ff cc 48 8d 3d 72 64 73 RSP: 0018:ffffc90003aafd78 EFLAGS: 00000286 RAX: d3d4042ff14ac900 RBX: 0000000000000202 RCX: 0000000000000046 RDX: 0000000000000000 RSI: ffffffff8e16b29d RDI: ffffffff8c27d100 RBP: ffff8880290229d8 R08: ffffffff9011ccb7 R09: 1ffffffff2023996 R10: dffffc0000000000 R11: fffffbfff2023997 R12: 0000000000000000 R13: 0000000000000000 R14: ffffffff8e75e5e0 R15: ffff888029021e80 rcu_lock_release include/linux/rcupdate.h:322 [inline] rcu_read_unlock include/linux/rcupdate.h:881 [inline] kill_proc_info+0x168/0x180 kernel/signal.c:1481 kill_something_info kernel/signal.c:1577 [inline] __do_sys_kill kernel/signal.c:3953 [inline] __se_sys_kill+0xd9/0x460 kernel/signal.c:3947 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x14d/0xf80 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7fb210b3dda7 RSP: 002b:00007ffe1e460eb8 EFLAGS: 00000217 ORIG_RAX: 000000000000003e RAX: ffffffffffffffda RBX: 0000000000000003 RCX: 00007fb210b3dda7 RDX: 0000000000000097 RSI: 0000000000000009 RDI: 0000000000000003 RBP: 00007ffe1e460efc R08: 7fffffffffffffff R09: 0000000000000000 R10: 4000000000000000 R11: 0000000000000217 R12: 0000000000000000 R13: 0000000000000064 R14: 000000000003f067 R15: 00007ffe1e460f50 rcu: rcu_preempt kthread starved for 3053 jiffies! g14521 f0x0 RCU_GP_WAIT_FQS(5) ->state=0x0 ->cpu=0 rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is now expected behavior. rcu: RCU grace-period kthread stack dump: task:rcu_preempt state:R running task stack:27744 pid:16 tgid:16 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5298 [inline] __schedule+0x15dd/0x52d0 kernel/sched/core.c:6911 __schedule_loop kernel/sched/core.c:6993 [inline] schedule+0x164/0x360 kernel/sched/core.c:7008 schedule_timeout+0x158/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x312/0x11d0 kernel/rcu/tree.c:2095 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2297 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 rcu: Stack dump where RCU GP kthread last ran: Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 3405 Comm: kworker/R-bat_e Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 03/18/2026 Workqueue: bat_events batadv_tt_purge RIP: 0010:get_current arch/x86/include/asm/current.h:25 [inline] RIP: 0010:__sanitizer_cov_trace_pc+0x8/0x70 kernel/kcov.c:216 Code: 8b 3d 04 8b 55 0c 48 89 de 5b e9 e3 99 5e 00 cc cc cc 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 48 8b 04 24 <65> 48 8b 0d 28 db 56 11 65 8b 15 49 db 56 11 81 e2 00 01 ff 00 74 RSP: 0018:ffffc900000078f0 EFLAGS: 00000046 RAX: ffffffff878d4630 RBX: 0000000000000000 RCX: 0000000000000100 RDX: ffff888033120000 RSI: 0000000000000000 RDI: 0000000000000000 RBP: ffff888156eed200 R08: 0000000000000003 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f0c R12: ffff88802b35bc00 R13: dffffc0000000000 R14: ffff888029c47000 R15: ffff888029c47408 FS: 0000000000000000(0000) GS:ffff888125457000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 0000557a11963a38 CR3: 00000000677c5000 CR4: 0000000000350ef0 Call Trace: dummy_validate_stream drivers/usb/gadget/udc/dummy_hcd.c:1244 [inline] dummy_urb_enqueue+0x270/0x780 drivers/usb/gadget/udc/dummy_hcd.c:1282 usb_hcd_submit_urb+0x328/0x1b70 drivers/usb/core/hcd.c:1542 ath9k_hif_usb_reg_in_cb+0x4d5/0x6f0 drivers/net/wireless/ath/ath9k/hif_usb.c:790 __usb_hcd_giveback_urb+0x376/0x540 drivers/usb/core/hcd.c:1657 dummy_timer+0xbbd/0x45d0 drivers/usb/gadget/udc/dummy_hcd.c:1995 __run_hrtimer kernel/time/hrtimer.c:1785 [inline] __hrtimer_run_queues+0x53a/0xcc0 kernel/time/hrtimer.c:1849 hrtimer_run_softirq+0x182/0x5a0 kernel/time/hrtimer.c:1866 handle_softirqs+0x22a/0x870 kernel/softirq.c:622 do_softirq+0x76/0xd0 kernel/softirq.c:523 __local_bh_enable_ip+0xf8/0x130 kernel/softirq.c:450 spin_unlock_bh include/linux/spinlock.h:395 [inline] batadv_tt_local_purge+0x2a7/0x340 net/batman-adv/translation-table.c:1315 batadv_tt_purge+0x35/0x9e0 net/batman-adv/translation-table.c:3509 process_one_work kernel/workqueue.c:3276 [inline] process_scheduled_works+0xb6e/0x18c0 kernel/workqueue.c:3359 rescuer_thread+0x827/0x1130 kernel/workqueue.c:3583 kthread+0x388/0x470 kernel/kthread.c:436 ret_from_fork+0x51e/0xb90 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 --- This report is generated by a bot. 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