From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from mail-oi1-f205.google.com (mail-oi1-f205.google.com [209.85.167.205]) (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 0FB853EB111 for ; Wed, 12 Aug 2026 08:52:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.167.205 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786524762; cv=none; b=BUT5gqFkcb6NQTKi+vKyyr7koBtaKEb6e44RgB/JxARSc94qQ9ap2Hu/wYaysFL3yLVyttH51SM5nZ0vOwe0BYdWACVDJsVm0xFsHaHFyj1yOsI9Vm064JMrRpfjLWp1GgsnmkWliNpu2W+ICBHsoH+JH8ZMPWKtp2SomwvdPW0= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1786524762; c=relaxed/simple; bh=rdvdAZ/LIltJL6/ZqnNsATM1FdCywDLJ5OVcE/EqH6M=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=obYvsl2RPxkMG8cDtYlcIGcVT7716cne0uSalB2ISuDixIiNQgWPbWkSL0jXOSVxyn9b3jA2kAYXbYM2lN77TnsIeWEWSR+aVxnPC3EJnV6T4MgVXUY+NASawbQi7uJX5VNuBIfK8wK+8lKd4VcS7hyTrzeFkvE0daTtVg9r7O4= 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=209.85.167.205 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-oi1-f205.google.com with SMTP id 5614622812f47-4b19ce23e5cso328983b6e.1 for ; Wed, 12 Aug 2026 01:52:40 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1786524760; x=1787129560; 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=geG1mDOLSLjhAUKKy7yx1hwfYe0E0r539anreB4VsuE=; b=Kfl8ECdILvlT8rx+EQ4Dv7O7fZVVh3jXgY2+aOPJDYTToBW4p2KfM3kZSFIV0kKCPb qnuRbni4OajUHDPPGyhHTuOx8BBF20/j4q4rpMnXR6Z20WxmC78kKys+EEhiPMzbtsZD MIu8zkAwhQi3rcJCDoZprJbshtpA8eVTqBKc4Uf4PgSkJ5elnTnF4QeNgiKqiTQE3Tkk 3gtw5i+PSvTqrG3kLUIg94E0h3bbUfJBon/9tPvusB0qJPrAkak+VO9OcWItsOVnASu6 T+BJtwhdBxaaqnDw33aSjVjcWfMbho9hfWYv5+0q+mZmc53CuUjF7WgRfJDMqsRrdih5 0zsA== X-Forwarded-Encrypted: i=1; AHgh+Rr/fMO56XgzoKp5albN5+hv2nOM+QJBOU921oIs95cXpc5wmmIrzrFv//8oUpWKyzPZwqpQJKq4b1I0KHs=@vger.kernel.org X-Gm-Message-State: AOJu0YxVIxFHYl/15mJDrtJy3q5zIIEFe9JGydXndw8KxXlP6RUAWxUK 7t4+RrOFA4s9L0tIWuJz8B9kv15wXKNu7MqEL05OnFchXlnNIA3ELT5amCfDOX8nMDZQt7nn2b6 h9pJyL7W3YiY2UijVGIEghIwuuAkG4ASgbsXTxgE+hayPW+e3jMM5qc6Qsjo= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6808:2209:b0:497:df42:1e04 with SMTP id 5614622812f47-4b210c4e4fbmr3012471b6e.18.1786524759956; Wed, 12 Aug 2026 01:52:39 -0700 (PDT) Date: Wed, 12 Aug 2026 01:52:39 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a7c3457.d5f0ebe7.22d851.000a.GAE@google.com> Subject: [syzbot] [net?] KCSAN: data-race in advance_sched / netdev_set_num_tc (2) From: syzbot To: davem@davemloft.net, edumazet@google.com, horms@kernel.org, jhs@mojatatu.com, jiri@resnulli.us, kuba@kernel.org, linux-kernel@vger.kernel.org, netdev@vger.kernel.org, pabeni@redhat.com, syzkaller-bugs@googlegroups.com Content-Type: text/plain; charset="UTF-8" Hello, syzbot found the following issue on: HEAD commit: 06cf61899d64 Merge tag 'x86-urgent-2026-08-08' of git://gi.. git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=10e95fb9580000 kernel config: https://syzkaller.appspot.com/x/.config?x=33c5ac947f6be69e dashboard link: https://syzkaller.appspot.com/bug?extid=a181d44496a497911353 compiler: Debian clang version 22.1.8 (++20260613092233+e80beda6e255-1~exp1~20260613092250.77), Debian LLD 22.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/d9d74d5e3090/disk-06cf6189.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/3933e211e222/vmlinux-06cf6189.xz kernel image: https://storage.googleapis.com/syzbot-assets/73924770119d/bzImage-06cf6189.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+a181d44496a497911353@syzkaller.appspotmail.com ================================================================== BUG: KCSAN: data-race in advance_sched / netdev_set_num_tc write to 0xffff88811ac5c036 of 2 bytes by task 4421 on cpu 0: netdev_set_num_tc+0x1b2/0x1d0 net/core/dev.c:3117 mqprio_init+0x68b/0xb90 net/sched/sch_mqprio.c:417 qdisc_create+0x57f/0x9c0 net/sched/sch_api.c:1346 __tc_modify_qdisc net/sched/sch_api.c:1780 [inline] tc_modify_qdisc+0x102a/0x1550 net/sched/sch_api.c:1844 rtnetlink_rcv_msg+0x6a7/0x720 net/core/rtnetlink.c:7085 netlink_rcv_skb+0x11e/0x220 net/netlink/af_netlink.c:2556 rtnetlink_rcv+0x1c/0x30 net/core/rtnetlink.c:7103 netlink_unicast_kernel net/netlink/af_netlink.c:1319 [inline] netlink_unicast+0x5a7/0x680 net/netlink/af_netlink.c:1345 netlink_sendmsg+0x5be/0x6f0 net/netlink/af_netlink.c:1900 sock_sendmsg_nosec net/socket.c:775 [inline] __sock_sendmsg net/socket.c:790 [inline] ____sys_sendmsg+0x532/0x580 net/socket.c:2684 ___sys_sendmsg+0x195/0x1e0 net/socket.c:2738 __sys_sendmsg net/socket.c:2770 [inline] __do_sys_sendmsg net/socket.c:2775 [inline] __se_sys_sendmsg net/socket.c:2773 [inline] __x64_sys_sendmsg+0xd4/0x160 net/socket.c:2773 x64_sys_call+0x194c/0x3020 arch/x86/include/generated/asm/syscalls_64.h:47 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x136/0x3c0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffff88811ac5c036 of 2 bytes by interrupt on cpu 1: netdev_get_num_tc include/linux/netdevice.h:2684 [inline] taprio_set_budgets net/sched/sch_taprio.c:667 [inline] advance_sched+0x58f/0x730 net/sched/sch_taprio.c:984 __run_hrtimer kernel/time/hrtimer.c:2032 [inline] __hrtimer_run_queues+0x1f8/0x510 kernel/time/hrtimer.c:2096 hrtimer_interrupt+0x257/0x810 kernel/time/hrtimer.c:2215 local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1051 [inline] __sysvec_apic_timer_interrupt+0x5f/0x1c0 arch/x86/kernel/apic/apic.c:1068 instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1062 [inline] sysvec_apic_timer_interrupt+0x6f/0x80 arch/x86/kernel/apic/apic.c:1062 asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:674 encoded_page_ptr include/linux/mm_types.h:268 [inline] free_pages_and_swap_cache+0xe1/0x3b0 mm/swap_state.c:577 __tlb_batch_free_encoded_pages mm/mmu_gather.c:138 [inline] tlb_batch_pages_flush mm/mmu_gather.c:151 [inline] tlb_flush_mmu_free mm/mmu_gather.c:417 [inline] tlb_flush_mmu+0x552/0x6d0 mm/mmu_gather.c:424 zap_pte_range mm/memory.c:1973 [inline] zap_pmd_range mm/memory.c:2020 [inline] zap_pud_range mm/memory.c:2048 [inline] zap_p4d_range mm/memory.c:2069 [inline] __zap_vma_range+0x2521/0x2c70 mm/memory.c:2109 unmap_vmas+0x200/0x310 mm/memory.c:2178 exit_mmap+0x1a2/0x5e0 mm/mmap.c:1300 __mmput+0x28/0x1c0 kernel/fork.c:1187 mmput+0x40/0x50 kernel/fork.c:1210 exit_mm+0x113/0x1a0 kernel/exit.c:615 do_exit+0x438/0x1500 kernel/exit.c:997 do_group_exit+0xfe/0x140 kernel/exit.c:1152 get_signal+0xe07/0xf10 kernel/signal.c:3046 arch_do_signal_or_restart+0x96/0x480 arch/x86/kernel/signal.c:337 __exit_to_user_mode_loop kernel/entry/common.c:66 [inline] exit_to_user_mode_loop+0x15d/0x8c0 kernel/entry/common.c:101 __exit_to_user_mode_prepare include/linux/irq-entry-common.h:207 [inline] syscall_exit_to_user_mode_prepare include/linux/irq-entry-common.h:230 [inline] syscall_exit_to_user_mode include/linux/entry-common.h:318 [inline] do_syscall_64+0x23c/0x3c0 arch/x86/entry/syscall_64.c:100 entry_SYSCALL_64_after_hwframe+0x77/0x7f value changed: 0x0000 -> 0x0001 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 4434 Comm: syz.1.244 Not tainted syzkaller #0 PREEMPT(lazy) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/24/2026 ================================================================== --- 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