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Mon, 19 Oct 2026 00:21:35 -0700 (PDT) Date: Mon, 19 Oct 2026 00:21:35 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6ad5c4ff.a6d1a155.34a93f.0112.GAE@google.com> Subject: [syzbot] [mm?] INFO: rcu detected stall in chrdev_open (7) From: syzbot To: davem@davemloft.net, david@ixit.cz, edumazet@kernel.org, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, oe-linux-nfc@lists.linux.dev, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" X-Rspamd-Server: rspam07 X-Rspam-User: X-Rspamd-Queue-Id: 188CB4000A X-Stat-Signature: xsncw9npzyfiw4pdgi4d5rzynsakmyjx X-HE-Tag: 1792394495-604390 X-HE-Meta: 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 LzPZLAsF 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 BgG4Xxec kx+k3VO5WqCzPOwHuaEUbXEz542AMB/3AX0U4QWJo7QHcGkujVvF1g/Kqt/zMut83n095Cs6BzVzjcso/yVwl3ZmJ6NdAJ18wMsbscH0cliZ6pjYyw4Y4oofkOQCva6IMdZfGt+17VJEGhSrWsjcUKXgteRNzSwplPPwUTJSHcmtoj8z9HsXPdXagEFRFoXw2W6TFQYJuBNJNIM3kmfggbpEUyXjFRH/DXe2DZEQ9VC55LXpYbZ4NKalO+FWyaurO+XLAh2P8Kpk+To9Ejyhjlo5LglmkZ6JzeHmOsxnefLmbIHXTirgYCI+SGe3VQhGcbNYiYkQB5+nnGjDzsEIU5GeEj60O14YgpuM7Y9awY/sJC7w4H4JDQ2rKc+x0cgYWlYlpTByHruBGYLyD8MYkbNf4ukOq+gpD1bUD3xel6b++JiHlObIrxBeAea93NyxTBEZj3gWFwQ= Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Hello, syzbot found the following issue on: HEAD commit: 24a19b953e2a Linux 7.3-rc7 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=16656f15580000 kernel config: https://syzkaller.appspot.com/x/.config?x=129d675874dbf896 dashboard link: https://syzkaller.appspot.com/bug?extid=899fe9063fef5929bd90 compiler: gcc (Debian 14.2.0-19) 14.2.0, GNU ld (GNU Binutils for Debian) 2.44 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/c36b6926be3e/disk-24a19b95.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/413d898eaf27/vmlinux-24a19b95.xz kernel image: https://storage.googleapis.com/syzbot-assets/ada3e66b70fc/bzImage-24a19b95.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+899fe9063fef5929bd90@syzkaller.appspotmail.com rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: rcu: Tasks blocked on level-0 rcu_node (CPUs 0-1): P12985/1:b..l rcu: (detected by 1, t=10502 jiffies, g=76689, q=368 ncpus=2) task:syz.0.1823 state:R running task stack:27232 pid:12985 tgid:12984 ppid:5600 task_flags:0x400040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 preempt_schedule_irq+0x4e/0x90 kernel/sched/core.c:7606 irqentry_exit_to_kernel_mode_preempt include/linux/irq-entry-common.h:468 [inline] irqentry_exit_to_kernel_mode include/linux/irq-entry-common.h:539 [inline] irqentry_exit+0x205/0xa10 kernel/entry/common.c:167 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 RIP: 0010:unwind_next_frame+0x17a/0x2090 arch/x86/kernel/unwind_orc.c:510 Code: ea 03 0f b6 04 02 4c 89 f2 83 e2 07 38 d0 7f 08 84 c0 0f 85 24 0a 00 00 48 89 e9 41 0f b6 45 35 48 ba 00 00 00 00 00 fc ff df <48> c1 e9 03 80 3c 11 00 0f 85 01 18 00 00 4d 8b 7d 48 3c 01 49 83 RSP: 0018:ffffc9000679f268 EFLAGS: 00000246 RAX: 0000000000000000 RBX: 0000000000000001 RCX: ffffc9000679f320 RDX: dffffc0000000000 RSI: ffffffff8c625500 RDI: ffffffff8e6af928 RBP: ffffc9000679f320 R08: 00000000c7ee03ff R09: 0000000000000007 R10: 0000000000000200 R11: 0000000000000001 R12: ffffc9000679f328 R13: ffffc9000679f2d8 R14: ffffc9000679f30d R15: ffff88803569cb00 arch_stack_walk+0x94/0xf0 arch/x86/kernel/stacktrace.c:25 stack_trace_save+0x8e/0xc0 kernel/stacktrace.c:122 kasan_save_stack+0x30/0x50 mm/kasan/common.c:57 kasan_save_track+0x14/0x30 mm/kasan/common.c:78 kasan_save_free_info+0x3b/0x70 mm/kasan/generic.c:584 poison_slab_object mm/kasan/common.c:264 [inline] __kasan_slab_free+0x5f/0x80 mm/kasan/common.c:296 kasan_slab_free include/linux/kasan.h:235 [inline] slab_free_hook mm/slub.c:2748 [inline] slab_free mm/slub.c:6509 [inline] kfree+0x22b/0x6d0 mm/slub.c:6802 apply_wqattrs_cleanup kernel/workqueue.c:5592 [inline] apply_workqueue_attrs_locked+0x96/0xe0 kernel/workqueue.c:5590 alloc_and_link_pwqs kernel/workqueue.c:5731 [inline] __alloc_workqueue+0x9a7/0x1950 kernel/workqueue.c:5984 alloc_workqueue_va kernel/workqueue.c:6033 [inline] alloc_workqueue_noprof+0xc7/0x130 kernel/workqueue.c:6049 nci_register_device+0x394/0xb80 net/nfc/nci/core.c:1269 virtual_ncidev_open+0x141/0x220 drivers/nfc/virtual_ncidev.c:153 misc_open+0x26d/0x450 drivers/char/misc.c:163 chrdev_open+0x234/0x6a0 fs/char_dev.c:411 do_dentry_open+0x6ab/0x14d0 fs/open.c:996 vfs_open+0x82/0x3f0 fs/open.c:1101 do_open fs/namei.c:4866 [inline] path_openat+0x19fa/0x2440 fs/namei.c:5029 do_file_open+0x20e/0x430 fs/namei.c:5058 do_sys_openat2+0x10f/0x1e0 fs/open.c:1417 do_sys_open fs/open.c:1423 [inline] __do_sys_openat fs/open.c:1439 [inline] __se_sys_openat fs/open.c:1434 [inline] __x64_sys_openat+0x12d/0x210 fs/open.c:1434 do_syscall_x64 arch/x86/entry/syscall_64.c:61 [inline] do_syscall_64+0x123/0x790 arch/x86/entry/syscall_64.c:84 entry_SYSCALL_64_after_hwframe+0x77/0x7f RIP: 0033:0x7f697c79e1d9 RSP: 002b:00007f697d6ac028 EFLAGS: 00000246 ORIG_RAX: 0000000000000101 RAX: ffffffffffffffda RBX: 00007f697ca25fa0 RCX: 00007f697c79e1d9 RDX: 0000000000000002 RSI: 0000200000000080 RDI: ffffffffffffff9c RBP: 00007f697c835888 R08: 0000000000000000 R09: 0000000000000000 R10: 0000000000000000 R11: 0000000000000246 R12: 0000000000000000 R13: 00007f697ca26038 R14: 00007f697ca25fa0 R15: 00007ffc729ea0a8 rcu: rcu_preempt kthread starved for 10502 jiffies! g76689 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:27560 pid:17 tgid:17 ppid:2 task_flags:0x208040 flags:0x00080000 Call Trace: context_switch kernel/sched/core.c:5533 [inline] __schedule+0x1259/0x6920 kernel/sched/core.c:7284 __schedule_loop kernel/sched/core.c:7361 [inline] schedule+0xdd/0x2c0 kernel/sched/core.c:7376 schedule_timeout+0x127/0x280 kernel/time/sleep_timeout.c:99 rcu_gp_fqs_loop+0x1a9/0x8f0 kernel/rcu/tree.c:2122 rcu_gp_kthread+0x17a/0x220 kernel/rcu/tree.c:2330 kthread+0x373/0x450 kernel/kthread.c:436 ret_from_fork+0x730/0xd60 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: 0 Comm: swapper/1 Tainted: G L syzkaller #0 PREEMPT(full) Tainted: [L]=SOFTLOCKUP Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 08/05/2026 RIP: 0010:pv_native_safe_halt+0xf/0x20 arch/x86/kernel/paravirt.c:64 Code: a7 96 02 e9 53 50 03 00 0f 1f 00 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 90 f3 0f 1e fa 66 90 0f 00 2d 93 48 17 00 fb f4 cc cc cc cc 66 2e 0f 1f 84 00 00 00 00 00 66 90 90 90 90 90 90 RSP: 0018:ffffc900001a7e00 EFLAGS: 00000242 RAX: 0000000001ea4ae3 RBX: ffff888020684b00 RCX: ffffffff8bd47235 RDX: 0000000000000001 RSI: ffffffff8e3e3486 RDI: ffffffff8c625580 RBP: ffffed10040d0960 R08: 0000000000000001 R09: ffffed10170667bd R10: ffff8880b8333deb R11: 0000000000000001 R12: 0000000000000000 R13: 0000000000000000 R14: 1ffff92000034fc4 R15: dffffc0000000000 FS: 0000000000000000(0000) GS:ffff888122a46000(0000) knlGS:0000000000000000 CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 CR2: 00007f38c4787800 CR3: 0000000036854000 CR4: 00000000003526f0 Call Trace: arch_safe_halt arch/x86/include/asm/paravirt.h:62 [inline] default_idle+0x9/0x10 arch/x86/kernel/process.c:768 default_idle_call+0x6c/0xb0 kernel/sched/idle.c:122 cpuidle_idle_call kernel/sched/idle.c:199 [inline] do_idle+0x3ae/0x5b0 kernel/sched/idle.c:355 cpu_startup_entry+0x4f/0x60 kernel/sched/idle.c:454 start_secondary+0x21d/0x2d0 arch/x86/kernel/smpboot.c:312 common_startup_64+0x13e/0x158 --- 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 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