From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oo2-f8.google.com (mail-oo2-f8.google.com [74.125.231.136]) (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 899583F54A7 for ; Thu, 3 Sep 2026 07:39:39 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=74.125.231.136 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788421181; cv=none; b=H4QHVvjrhJiFepBVf9ZXNdSBwjUbdiyuuMgUGORDbRA/FzlFZyVdV8Yd6vp92xf4SUhLisP7kRG3nRLVNaxf89cGrMVEF4dBAw8REDPlg7N3+OUiP2JqPYGUFfmlYA7SFzy+qsXnBYmRh3m8QlLhhLdj4fkXF66NSN3B5GMO9dM= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1788421181; c=relaxed/simple; bh=k4LOqtUosmr6ZyknwbppLFe4OcI5ltMy4YYox8qoGag=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=J2NiEXw+M40hkL8w2ZiRpVKDJcnbNsCr8bNcerzMME4q8qUhpffRYXSPP3qzqOWycRdr5QsdF2+/uPCDqjGgXOkyTsY5veCg9fXzsP572vFHa9+2WuYCFwI6HikJsJY1vJOjjquuaGfx0qZqF5JeffV7eTC77vYjtwtf9c/ZLl8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com; arc=none smtp.client-ip=74.125.231.136 Authentication-Results: smtp.subspace.kernel.org; dmarc=fail (p=none dis=none) header.from=syzkaller.appspotmail.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=M3KW2WVRGUFZ5GODRSRYTGD7.apphosting.bounces.google.com Received: by mail-oo2-f8.google.com with SMTP id 006d021491bc7-6b128c3af4bso99120eaf.0 for ; Thu, 03 Sep 2026 00:39:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1788421178; x=1789025978; h=content-type:to:from:subject:message-id:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to :content-type; bh=QkbPX+/Gt8vrXhrXwYE9Oil0+rxtEjRaW6SUbOfN9XQ=; b=pC9H8juuSnizfU5MDC+PE6O/QNnLDVUyVKP+4sb9UvPJVlA5i0J3eMMl9iweQAYskN b5g93rJuz9bMTRgggyEmiQRLI550jRqAkVW22Uy7MqdRyy9BrP+n75uqO3sQ/kGqN1y0 eMP5kSbyvVJ+f3zCC0DKldQIc70nT4IJC/8+pWHBXeB03xDoDJV8YGCOc5+8W9KyOPog 0jDMGsVyq+Z7Ua1k/RsOQpSiqBXmRoes/7pVFlWKH5oALTBZmeIsbUdbJcBVvUMxaEuk dmaRSqN6Lvyb9vkg8EZZ59RziUPkkv6rNvoYv9NcOYITsxXuuBCPDTs60BV9e9x8VJgf +dGA== X-Forwarded-Encrypted: i=1; AKwUvBy38crYn3HJ3M1UzvIdx+yaj9pTzQcuQ8eCvHMI1GVjF4CG6AxXC3rT0Jaqhs510AfjIEUvil+Ojmgfa+4=@vger.kernel.org X-Gm-Message-State: AFuF++l8PY6S3xm4sfUt0RJ5H5A2VUx4JJURJA0XUsttOTulmYtdnHNd DRoxdP/Lg/wl6h1b1ooyXIDjvuzYpg3jZ+sAzNyRA7mgQ1ZFTKHV944G5Qk8kaF03UqFqtkckAf WPHeWddhqesqooNFW9taN8qIDLWT4hfhnMlVVzwRaSw+v1vaeyHJ0KhLqJ18= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:619:b0:6ae:9815:7c8e with SMTP id 006d021491bc7-6b48102eaa1mr7838702eaf.21.1788421178408; Thu, 03 Sep 2026 00:39:38 -0700 (PDT) Date: Thu, 03 Sep 2026 00:39:38 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a99243a.2e567484.299ffc.0008.GAE@google.com> Subject: [syzbot] [kernfs?] INFO: rcu detected stall in kernfs_fop_release (3) From: syzbot To: driver-core@lists.linux.dev, gregkh@linuxfoundation.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, syzkaller-bugs@googlegroups.com, tj@kernel.org Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 1b78070aaef6 Merge tag 'net-7.3-rc1' of git://git.kernel.o.. git tree: net-next console output: https://syzkaller.appspot.com/x/log.txt?x=107d7d79580000 kernel config: https://syzkaller.appspot.com/x/.config?x=5e4e3a0e188a497e dashboard link: https://syzkaller.appspot.com/bug?extid=087d9dac1f398074ca9f compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 syz repro: https://syzkaller.appspot.com/x/repro.syz?x=13dc2379580000 C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1286ac15580000 Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/18856a03a9a3/disk-1b78070a.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/cc2bc68d7ef4/vmlinux-1b78070a.xz kernel image: https://storage.googleapis.com/syzbot-assets/05a5e00f8f91/bzImage-1b78070a.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+087d9dac1f398074ca9f@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: 0-...!: (1 GPs behind) idle=c15c/1/0x4000000000000000 softirq=16029/16030 fqs=6 rcu: (detected by 1, t=10504 jiffies, g=15973, q=1121 ncpus=2) Sending NMI from CPU 1 to CPUs 0: NMI backtrace for cpu 0 CPU: 0 UID: 0 PID: 5842 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:should_restart_cycle net/sched/sch_taprio.c:-1 [inline] RIP: 0010:advance_sched+0x2fe/0xc80 net/sched/sch_taprio.c:955 Code: 89 f8 48 c1 e8 03 48 b9 00 00 00 00 00 fc ff df 80 3c 08 00 74 08 4c 89 ff e8 3e fc 4b f8 4d 8b 3f 4d 39 e7 0f 84 a7 00 00 00 <48> 8b 04 24 48 8d 98 28 01 00 00 48 89 d8 48 c1 e8 03 48 b9 00 00 RSP: 0018:ffffc90000007cf8 EFLAGS: 00000006 RAX: 1ffff1100639ac28 RBX: 0000000000000000 RCX: dffffc0000000000 RDX: 0000000001000001 RSI: 0000000000000000 RDI: 0000001db0a1a72b RBP: 0000000000000000 R08: 0000000001000001 R09: 0000000000000004 R10: dffffc0000000000 R11: fffff52000000f90 R12: ffff888031cd6910 R13: 0000000000000001 R14: 0000001db0a1a72b R15: ffff888076d4bd40 FS: 00007ff72c957880(0000) GS:ffff888124ce0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe39b15f44 CR3: 0000000075580000 CR4: 00000000003526f0 Call Trace: __run_hrtimer kernel/time/hrtimer.c:2067 [inline] __hrtimer_run_queues+0x3bc/0xa10 kernel/time/hrtimer.c:2124 hrtimer_interrupt+0x4cd/0xaa0 kernel/time/hrtimer.c:2243 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x102/0x430 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:on_stack arch/x86/include/asm/stacktrace.h:58 [inline] RIP: 0010:stack_access_ok arch/x86/kernel/unwind_orc.c:409 [inline] RIP: 0010:deref_stack_reg arch/x86/kernel/unwind_orc.c:419 [inline] RIP: 0010:unwind_next_frame+0xb86/0x2550 arch/x86/kernel/unwind_orc.c:614 Code: fc ff df 41 80 3c 04 00 74 09 e8 a5 7f bf 00 4c 8b 04 24 49 8d 50 f8 4d 8b 6e 10 48 b8 00 00 00 00 00 fc ff df 48 8b 4c 24 10 <0f> b6 04 01 84 c0 0f 85 3b 14 00 00 41 83 3e 00 0f 95 c0 49 39 d7 RSP: 0018:ffffc90003cff8a0 EFLAGS: 00000246 RAX: dffffc0000000000 RBX: 1ffff9200079ff2a RCX: 1ffff9200079ff29 RDX: ffffc90003cffcb0 RSI: 0000000000000002 RDI: ffffc90003cff958 RBP: 1ffffffff22401c0 R08: ffffc90003cffcb8 R09: 0000000000000000 R10: 0000000000000000 R11: ffffffff8ed5c6e0 R12: 1ffff9200079ff2b R13: ffffc90003d00000 R14: ffffc90003cff948 R15: ffffc90003cf8000 arch_stack_walk+0x11b/0x150 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0xa9/0x100 kernel/stacktrace.c:122 kasan_save_stack mm/kasan/common.c:57 [inline] kasan_save_track+0x3e/0x80 mm/kasan/common.c:78 kasan_save_free_info+0x40/0x50 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:253 [inline] __kasan_slab_free+0x5c/0x80 mm/kasan/common.c:285 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6499 [inline] kmem_cache_free+0x182/0x650 mm/slub.c:6626 seq_release+0x63/0x70 fs/seq_file.c:357 kernfs_fop_release+0x2f8/0x440 fs/kernfs/file.c:777 __fput+0x418/0xa50 fs/file_table.c:512 fput_close_sync+0x11f/0x240 fs/file_table.c:617 __do_sys_close fs/open.c:1560 [inline] __se_sys_close fs/open.c:1545 [inline] __x64_sys_close+0x7e/0x110 fs/open.c:1545 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff72ca51a67 Code: 44 00 00 48 83 ec 10 48 63 ff 45 31 c9 45 31 c0 6a 01 31 c9 e8 ca 19 f9 ff 48 83 c4 18 c3 0f 1f 44 00 00 b8 03 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 01 c3 48 8b 15 61 b3 0d 00 f7 d8 64 89 02 b8 RSP: 002b:00007ffe39b145d8 EFLAGS: 00000297 ORIG_RAX: 0000000000000003 RAX: ffffffffffffffda RBX: 0000557f662c60d0 RCX: 00007ff72ca51a67 RDX: 00007ff72cb2bea0 RSI: 0000557f662dc3e0 RDI: 0000000000000008 RBP: 00007ff72cb2bff0 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000297 R12: 0000000000000000 R13: 3d45505954564544 R14: 3d5845444e494649 R15: 3d454d414e564544 rcu: rcu_preempt kthread starved for 10474 jiffies! g15973 f0x0 RCU_GP_WAIT_FQS(5) ->state=R ->cpu=1 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:27496 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5520 [inline] __schedule+0x17d4/0x5820 kernel/sched/core.c:7270 __schedule_loop kernel/sched/core.c:7347 [inline] schedule+0x164/0x2b0 kernel/sched/core.c:7362 schedule_timeout+0x152/0x2c0 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x30c/0x11f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x9e/0x2b0 kernel/rcu/tree.c:2330 kthread+0x38b/0x480 kernel/kthread.c:436 ret_from_fork+0x514/0xb70 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: CPU: 1 UID: 0 PID: 4986 Comm: udevd Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 RIP: 0010:csd_lock_wait kernel/smp.c:363 [inline] RIP: 0010:csd_lock kernel/smp.c:396 [inline] RIP: 0010:smp_call_function_many_cond+0x628/0x1500 kernel/smp.c:944 Code: 00 44 8b 3b 44 89 fe 83 e6 01 31 ff e8 51 51 0c 00 41 83 e7 01 75 07 e8 46 4c 0c 00 eb 3f f3 90 48 b8 00 00 00 00 00 fc ff df <41> 0f b6 04 04 84 c0 75 0f f7 03 01 00 00 00 74 1d e8 22 4c 0c 00 RSP: 0018:ffffc90002e0f420 EFLAGS: 00000293 RAX: dffffc0000000000 RBX: ffff8880b8643708 RCX: ffff88807e928000 RDX: 0000000000000000 RSI: 0000000000000001 RDI: 0000000000000000 RBP: ffffc90002e0f570 R08: ffff88807e92959f R09: 1ffff1100fd252b3 R10: dffffc0000000000 R11: 0000000000000000 R12: 1ffff110170c86e1 R13: 0000000000000000 R14: ffff8880b8643700 R15: 0000000000000001 FS: 00007ff72c957880(0000) GS:ffff888124de0000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007ffe39b19040 CR3: 000000007eae6000 CR4: 00000000003526f0 Call Trace: __flush_tlb_multi arch/x86/include/asm/paravirt.h:46 [inline] flush_tlb_multi arch/x86/mm/tlb.c:1361 [inline] flush_tlb_mm_range+0x8ff/0x1090 arch/x86/mm/tlb.c:1435 dup_mmap+0x1758/0x1dc0 mm/mmap.c:1884 dup_mm kernel/fork.c:1543 [inline] copy_mm+0x11a/0x480 kernel/fork.c:1595 copy_process+0x1e75/0x43e0 kernel/fork.c:2307 kernel_clone+0x2d7/0x940 kernel/fork.c:2766 __do_sys_clone kernel/fork.c:2908 [inline] __se_sys_clone kernel/fork.c:2892 [inline] __x64_sys_clone+0x1b6/0x230 kernel/fork.c:2892 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x166/0x520 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7ff72ca2d636 Code: 89 df e8 6d e8 f6 ff 45 31 c0 31 d2 31 f6 64 48 8b 04 25 10 00 00 00 bf 11 00 20 01 4c 8d 90 d0 02 00 00 b8 38 00 00 00 0f 05 <48> 3d 00 f0 ff ff 77 52 89 c5 85 c0 75 31 64 48 8b 04 25 10 00 00 RSP: 002b:00007ffe39b18a50 EFLAGS: 00000246 ORIG_RAX: 0000000000000038 RAX: ffffffffffffffda RBX: 00007ffe39b18a58 RCX: 00007ff72ca2d636 RDX: 0000000000000000 RSI: 0000000000000000 RDI: 0000000001200011 RBP: 0000557f662a4910 R08: 0000000000000000 R09: 0000557f662ac8e0 R10: 00007ff72c957b50 R11: 0000000000000246 R12: 00007ffe39b18e10 R13: 0000000000000000 R14: 0000000000000000 R15: 0000000000000000 --- This report is generated by a bot. It may contain errors. See https://goo.gl/tpsmEJ for more information about syzbot. syzbot engineers can be reached at syzkaller@googlegroups.com. syzbot will keep track of this issue. See: https://goo.gl/tpsmEJ#status for how to communicate with syzbot. If the report is already addressed, let syzbot know by replying with: #syz fix: exact-commit-title If you want syzbot to run the reproducer, reply with: #syz test: git://repo/address.git branch-or-commit-hash If you attach or paste a git patch, syzbot will apply it before testing. If you want to overwrite report's subsystems, reply with: #syz set subsystems: new-subsystem (See the list of subsystem names on the web dashboard) If the report is a duplicate of another one, reply with: #syz dup: exact-subject-of-another-report If you want to undo deduplication, reply with: #syz undup