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 92F7C45BD7A for ; Mon, 18 May 2026 12:55:26 +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=1779108928; cv=none; b=WngCkt/LYQvuJF/Wfp+oNJbES9jDhcvJGxXKLQB2/KwpX+0nJsxjBpXq0+l5Z6R6egDCwJaAZ8+ODA0U+NKunNiP5toQhHVqxE0YMFjngcjYGHbLQHgH2CmXMK+yBT9uYO9wrzTc9hy9rvG6vhmxWXyGTj4KGZkVmbWyv3wn7gw= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1779108928; c=relaxed/simple; bh=tK840hvZ43HKLNXZMViigHa1fyiKBLarM4XHWNLIb3I=; h=MIME-Version:Date:Message-ID:Subject:From:To:Content-Type; b=Dqszsd7evYmur///ATj0tEvQBx+5WOyeEx7mJpdvBvQLbgpaPN6JXTB4cnrfJxWqmeoHZ9q2NN47tQpzOpZsZfy7/yYrtTaUE/IrnvBegb7dvBN01dbCTO+QisNxL79Gu1VmzO0C3IZBCnqNKhkBRCNUzVcf+JxporMfuROEZFM= 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=209.85.161.77 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-oo1-f77.google.com with SMTP id 006d021491bc7-69b4c167215so4861831eaf.0 for ; Mon, 18 May 2026 05:55:26 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1779108925; x=1779713725; h=to:from:subject:message-id:date:mime-version:x-gm-message-state :from:to:cc:subject:date:message-id:reply-to; bh=50RR+AgzK0YnVUZK+aMpMmbSzPep288wPSaMMJAJSKk=; b=STS2TKY9XkiF3KVrqHdt26CPGv4GeHSCrBBt/1POw2ILbxpdkJrHvyfCnVQyG/x6/o GmXqNI3yO5QW1O2IPKYHvoVMAoy/zlky5qXYH3kh2hN3yDqE8k8p4uh7vMEA5VUxNY+y wPzEJ1LeWFsLkpeZ4c+wVJ7DulLxHuFsKdpgduqd9uxsxoL7vhLO+aKZZo6v6iCrnRGe yGOUvuEH0A3sFp4ny4G3llMXc49kpFSOvIffXGY79pxqBNf4wMmCpnZD2d0HmBZTysQS kol/4/8WTjQ+kKMQHvYlK98yumIxBOuR/RlyXjbF2UH2/n3kRIAmbtUrWOVgJ3gsUdgT RNWQ== X-Forwarded-Encrypted: i=1; AFNElJ9frgtGGnrLm2uEcN5I76x3ykPuivQ/73TiZvZ3aST3Axt9OHZ6eFHU+Sxys7w8BO1KxvgJnl6OMht9hXA=@vger.kernel.org X-Gm-Message-State: AOJu0YwS59+1A462ONvrA47D7pPm7kTyzXcpnXmaO5QNCGvhc55lTdq8 9qq2CJJli8fhbbd4lRE0ePRqMsYKWKoBr1gaO9BCa7+b8OEnE3WTY1V17WmUctC6NPSg3kOUFrE 7vtQseqTaN0jD3X6bBsutrP4Dcc0bQuWxEE1MQWrndtRKJEAQ+k/qeXEW09Q= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a4a:e6b7:0:b0:696:8cb7:3167 with SMTP id 006d021491bc7-69b8803f382mr7832663eaf.14.1779108925664; Mon, 18 May 2026 05:55:25 -0700 (PDT) Date: Mon, 18 May 2026 05:55:25 -0700 X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a0b0c3d.050a0220.2251c6.000e.GAE@google.com> Subject: [syzbot] [kernel?] KCSAN: data-race in ktime_get_real_seconds / timekeeping_update_from_shadow (4) From: syzbot To: jstultz@google.com, linux-kernel@vger.kernel.org, sboyd@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: 5200f5f493f7 Linux 7.1-rc4 git tree: upstream console output: https://syzkaller.appspot.com/x/log.txt?x=11cba536580000 kernel config: https://syzkaller.appspot.com/x/.config?x=2e40c0f41e01837e dashboard link: https://syzkaller.appspot.com/bug?extid=72789cd1697965e714ca compiler: Debian clang version 21.1.8 (++20251221033036+2078da43e25a-1~exp1~20251221153213.50), Debian LLD 21.1.8 Unfortunately, I don't have any reproducer for this issue yet. Downloadable assets: disk image: https://storage.googleapis.com/syzbot-assets/f68e006a0a6d/disk-5200f5f4.raw.xz vmlinux: https://storage.googleapis.com/syzbot-assets/0eab03c0765f/vmlinux-5200f5f4.xz kernel image: https://storage.googleapis.com/syzbot-assets/9a6094a6b4b6/bzImage-5200f5f4.xz IMPORTANT: if you fix the issue, please add the following tag to the commit: Reported-by: syzbot+72789cd1697965e714ca@syzkaller.appspotmail.com ================================================================== BUG: KCSAN: data-race in ktime_get_real_seconds / timekeeping_update_from_shadow write to 0xffffffff893a8488 of 304 bytes by task 5194 on cpu 0: timekeeping_update_from_shadow+0x40d/0x440 kernel/time/timekeeping.c:829 __timekeeping_inject_offset+0x45c/0x490 kernel/time/timekeeping.c:1661 __do_adjtimex kernel/time/timekeeping.c:2881 [inline] do_adjtimex+0x390/0x7f0 kernel/time/timekeeping.c:2914 posix_clock_realtime_adj+0x15/0x20 kernel/time/posix-timers.c:207 do_clock_adjtime kernel/time/posix-timers.c:1154 [inline] __do_sys_clock_adjtime kernel/time/posix-timers.c:1166 [inline] __se_sys_clock_adjtime kernel/time/posix-timers.c:1157 [inline] __x64_sys_clock_adjtime+0x145/0x1d0 kernel/time/posix-timers.c:1157 x64_sys_call+0x2794/0x3020 arch/x86/include/generated/asm/syscalls_64.h:306 do_syscall_x64 arch/x86/entry/syscall_64.c:63 [inline] do_syscall_64+0x12c/0x3b0 arch/x86/entry/syscall_64.c:94 entry_SYSCALL_64_after_hwframe+0x77/0x7f read to 0xffffffff893a84c0 of 8 bytes by task 3377 on cpu 1: ktime_get_real_seconds+0x15/0x30 kernel/time/timekeeping.c:1156 sched_sync_hw_clock kernel/time/ntp.c:508 [inline] sync_hw_clock+0x2a8/0x380 kernel/time/ntp.c:665 process_one_work kernel/workqueue.c:3314 [inline] process_scheduled_works+0x4f0/0x9c0 kernel/workqueue.c:3397 worker_thread+0x58a/0x780 kernel/workqueue.c:3478 kthread+0x22a/0x280 kernel/kthread.c:436 ret_from_fork+0x146/0x330 arch/x86/kernel/process.c:158 ret_from_fork_asm+0x1a/0x30 arch/x86/entry/entry_64.S:245 value changed: 0x0000000077359b00 -> 0x0000000077359c00 Reported by Kernel Concurrency Sanitizer on: CPU: 1 UID: 0 PID: 3377 Comm: kworker/1:3 Not tainted syzkaller #0 PREEMPT(full) Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 04/18/2026 Workqueue: events_freezable_pwr_efficient sync_hw_clock ================================================================== --- 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