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X-CSE-MsgGUID: Xg7zxYz8TLC+L6NGk6zaPA== X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="6.19,226,1754982000"; d="scan'208";a="186809381" Received: from vcostago-desk1.jf.intel.com (HELO vcostago-desk1) ([10.88.27.140]) by orviesa005-auth.jf.intel.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 13 Oct 2025 14:51:00 -0700 From: Vinicius Costa Gomes To: Jamal Hadi Salim , Eric Dumazet Cc: syzbot , davem@davemloft.net, dsahern@kernel.org, hdanton@sina.com, horms@kernel.org, kuba@kernel.org, linux-kernel@vger.kernel.org, linux-mm@kvack.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com, tglx@linutronix.de Subject: Re: [syzbot] [net?] [mm?] INFO: rcu detected stall in inet_rtm_newaddr (2) In-Reply-To: References: <681a1770.050a0220.a19a9.000d.GAE@google.com> <68ea0a24.050a0220.91a22.01ca.GAE@google.com> Date: Mon, 13 Oct 2025 14:51:18 -0700 Message-ID: <87347mmpwp.fsf@intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=utf-8 Content-Transfer-Encoding: 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X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: List-Subscribe: List-Unsubscribe: Jamal Hadi Salim writes: > On Sat, Oct 11, 2025 at 5:42=E2=80=AFAM Eric Dumazet wrote: >> >> On Sat, Oct 11, 2025 at 12:41=E2=80=AFAM syzbot >> wrote: >> > >> > syzbot has found a reproducer for the following issue on: >> > >> > HEAD commit: 18a7e218cfcd Merge tag 'net-6.18-rc1' of git://git.ker= nel... >> > git tree: net-next >> > console output: https://syzkaller.appspot.com/x/log.txt?x=3D12504dcd98= 0000 >> > kernel config: https://syzkaller.appspot.com/x/.config?x=3D61ab7fa743= df0ec1 >> > dashboard link: https://syzkaller.appspot.com/bug?extid=3D51cd74c5dfea= fd65e488 >> > compiler: Debian clang version 20.1.8 (++20250708063551+0c9f909b= 7976-1~exp1~20250708183702.136), Debian LLD 20.1.8 >> > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=3D14d2a542= 580000 >> > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=3D142149e258= 0000 >> > >> > Downloadable assets: >> > disk image: https://storage.googleapis.com/syzbot-assets/7a01e6dce97e/= disk-18a7e218.raw.xz >> > vmlinux: https://storage.googleapis.com/syzbot-assets/5e1b7e41427f/vml= inux-18a7e218.xz >> > kernel image: https://storage.googleapis.com/syzbot-assets/69b55860120= 9/bzImage-18a7e218.xz >> > >> > IMPORTANT: if you fix the issue, please add the following tag to the c= ommit: >> > Reported-by: syzbot+51cd74c5dfeafd65e488@syzkaller.appspotmail.com >> > >> > sched: DL replenish lagged too much >> > rcu: INFO: rcu_preempt detected stalls on CPUs/tasks: >> > rcu: 0-...!: (2 GPs behind) idle=3D7754/1/0x4000000000000000 softir= q=3D15464/15465 fqs=3D1 >> > rcu: (detected by 1, t=3D10502 jiffies, g=3D11321, q=3D371 ncpus=3D= 2) >> > Sending NMI from CPU 1 to CPUs 0: >> > NMI backtrace for cpu 0 >> > CPU: 0 UID: 0 PID: 5948 Comm: syz-executor Not tainted syzkaller #0 PR= EEMPT(full) >> > Hardware name: Google Google Compute Engine/Google Compute Engine, BIO= S Google 10/02/2025 >> > RIP: 0010:rb_insert_color_cached include/linux/rbtree.h:113 [inline] >> > RIP: 0010:rb_add_cached include/linux/rbtree.h:183 [inline] >> > RIP: 0010:timerqueue_add+0x1a8/0x200 lib/timerqueue.c:40 >> > Code: e7 31 f6 e8 6a 0c de f6 42 80 3c 2b 00 74 08 4c 89 f7 e8 7b 0a d= e f6 4d 89 26 4d 8d 7e 08 4c 89 f8 48 c1 e8 03 42 80 3c 28 00 <74> 08 4c 89= ff e8 5e 0a de f6 4d 89 27 4d 85 e4 40 0f 95 c5 eb 07 >> > RSP: 0018:ffffc90000007cf0 EFLAGS: 00000046 >> > RAX: 1ffff110170c4f83 RBX: 1ffff110170c4f82 RCX: 0000000000000000 >> > RDX: 0000000000000000 RSI: 0000000000000000 RDI: ffff88805de72358 >> > RBP: 0000000000000000 R08: ffff88805de72357 R09: 0000000000000000 >> > R10: ffff88805de72340 R11: ffffed100bbce46b R12: ffff88805de72340 >> > R13: dffffc0000000000 R14: ffff8880b8627c10 R15: ffff8880b8627c18 >> > FS: 000055557c657500(0000) GS:ffff888125d0f000(0000) knlGS:0000000000= 000000 >> > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >> > CR2: 0000200000000600 CR3: 000000002ee76000 CR4: 00000000003526f0 >> > Call Trace: >> > >> > __run_hrtimer kernel/time/hrtimer.c:1794 [inline] >> > __hrtimer_run_queues+0x656/0xc60 kernel/time/hrtimer.c:1841 >> > hrtimer_interrupt+0x45b/0xaa0 kernel/time/hrtimer.c:1903 >> > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1041 [inline] >> > __sysvec_apic_timer_interrupt+0x108/0x410 arch/x86/kernel/apic/apic.c= :1058 >> > instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1052 [i= nline] >> > sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1052 >> > >> > >> > asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtent= ry.h:702 >> > RIP: 0010:pv_vcpu_is_preempted arch/x86/include/asm/paravirt.h:579 [in= line] >> > RIP: 0010:vcpu_is_preempted arch/x86/include/asm/qspinlock.h:63 [inlin= e] >> > RIP: 0010:owner_on_cpu include/linux/sched.h:2282 [inline] >> > RIP: 0010:mutex_spin_on_owner+0x189/0x360 kernel/locking/mutex.c:361 >> > Code: b6 04 30 84 c0 0f 85 59 01 00 00 48 8b 44 24 08 8b 18 48 8b 44 2= 4 48 42 80 3c 30 00 74 0c 48 c7 c7 90 8c fa 8d e8 a7 cd 88 00 <48> 83 3d ff= 27 5e 0c 00 0f 84 b9 01 00 00 48 89 df e8 41 e0 d5 ff >> > RSP: 0018:ffffc900034c7428 EFLAGS: 00000246 >> > RAX: 1ffffffff1bf5192 RBX: 0000000000000001 RCX: ffffffff819c6588 >> > RDX: 0000000000000000 RSI: 0000000000000008 RDI: ffffffff8f4df8a0 >> > RBP: 1ffffffff1e9bf14 R08: ffffffff8f4df8a7 R09: 1ffffffff1e9bf14 >> > R10: dffffc0000000000 R11: fffffbfff1e9bf15 R12: ffffffff8f4df8a0 >> > R13: ffffffff8f4df8f0 R14: dffffc0000000000 R15: ffff8880267a9e40 >> > mutex_optimistic_spin kernel/locking/mutex.c:464 [inline] >> > __mutex_lock_common kernel/locking/mutex.c:602 [inline] >> > __mutex_lock+0x311/0x1350 kernel/locking/mutex.c:760 >> > rtnl_net_lock include/linux/rtnetlink.h:130 [inline] >> > inet_rtm_newaddr+0x3b0/0x18b0 net/ipv4/devinet.c:978 >> > rtnetlink_rcv_msg+0x7cf/0xb70 net/core/rtnetlink.c:6954 >> > netlink_rcv_skb+0x205/0x470 net/netlink/af_netlink.c:2552 >> > netlink_unicast_kernel net/netlink/af_netlink.c:1320 [inline] >> > netlink_unicast+0x82f/0x9e0 net/netlink/af_netlink.c:1346 >> > netlink_sendmsg+0x805/0xb30 net/netlink/af_netlink.c:1896 >> > sock_sendmsg_nosec net/socket.c:727 [inline] >> > __sock_sendmsg+0x21c/0x270 net/socket.c:742 >> > __sys_sendto+0x3bd/0x520 net/socket.c:2244 >> > __do_sys_sendto net/socket.c:2251 [inline] >> > __se_sys_sendto net/socket.c:2247 [inline] >> > __x64_sys_sendto+0xde/0x100 net/socket.c:2247 >> > do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] >> > do_syscall_64+0xfa/0xfa0 arch/x86/entry/syscall_64.c:94 >> > entry_SYSCALL_64_after_hwframe+0x77/0x7f >> > RIP: 0033:0x7faade790d5c >> > Code: 2a 5f 02 00 44 8b 4c 24 2c 4c 8b 44 24 20 89 c5 44 8b 54 24 28 4= 8 8b 54 24 18 b8 2c 00 00 00 48 8b 74 24 10 8b 7c 24 08 0f 05 <48> 3d 00 f0= ff ff 77 34 89 ef 48 89 44 24 08 e8 70 5f 02 00 48 8b >> > RSP: 002b:00007ffdd2e3b670 EFLAGS: 00000293 ORIG_RAX: 000000000000002c >> > RAX: ffffffffffffffda RBX: 00007faadf514620 RCX: 00007faade790d5c >> > RDX: 0000000000000028 RSI: 00007faadf514670 RDI: 0000000000000003 >> > RBP: 0000000000000000 R08: 00007ffdd2e3b6c4 R09: 000000000000000c >> > R10: 0000000000000000 R11: 0000000000000293 R12: 0000000000000003 >> > R13: 0000000000000000 R14: 00007faadf514670 R15: 0000000000000000 >> > >> > rcu: rcu_preempt kthread timer wakeup didn't happen for 10499 jiffies!= g11321 f0x0 RCU_GP_WAIT_FQS(5) ->state=3D0x402 >> > rcu: Possible timer handling issue on cpu=3D0 timer-softirq=3D4286 >> > rcu: rcu_preempt kthread starved for 10500 jiffies! g11321 f0x0 RCU_GP= _WAIT_FQS(5) ->state=3D0x402 ->cpu=3D0 >> > rcu: Unless rcu_preempt kthread gets sufficient CPU time, OOM is no= w expected behavior. >> > rcu: RCU grace-period kthread stack dump: >> > task:rcu_preempt state:I stack:27224 pid:16 tgid:16 ppid:2 = task_flags:0x208040 flags:0x00080000 >> > Call Trace: >> > >> > context_switch kernel/sched/core.c:5325 [inline] >> > __schedule+0x1798/0x4cc0 kernel/sched/core.c:6929 >> > __schedule_loop kernel/sched/core.c:7011 [inline] >> > schedule+0x165/0x360 kernel/sched/core.c:7026 >> > schedule_timeout+0x12b/0x270 kernel/time/sleep_timeout.c:99 >> > rcu_gp_fqs_loop+0x301/0x1540 kernel/rcu/tree.c:2083 >> > rcu_gp_kthread+0x99/0x390 kernel/rcu/tree.c:2285 >> > kthread+0x711/0x8a0 kernel/kthread.c:463 >> > ret_from_fork+0x4bc/0x870 arch/x86/kernel/process.c:158 >> > ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 >> > >> > >> > >> > --- >> > 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 testin= g. >> >> Yet another taprio report. >> >> If taprio can not be fixed, perhaps we should remove it from the >> kernel, or clearly marked as broken. >> (Then ask syzbot to no longer include it) > > Agreed on the challenge with taprio. > We need the stakeholders input: Vinicius - are you still working in > this space? Vladimir you also seem to have interest (or maybe nxp > does) in this? No, I am not working on this space anymore. I will talk with other Intel folks (and my manager) and see what we can do. But if others that find it useful can help even better. > At a minimum, we should mark it as broken unless the stakeholders want > to actively fix these issues. > Would syzbot still look at it if it was marked broken? > > cheers, > jamal > Cheers, --=20 Vinicius