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bh=TXiU2Y758Ana+gXTRNJ7cGEemsdXEpDtx+PeKTGcMqo=; b=KP8uSR4vsTWPAj3XhOCpB6QeNPLsFVVnfwtNXrb8yxbL9CUeZ5TuJv6v1/pw/w2vAEq4q7 GFlGL7xgTuUCqZ6D5iYCKmZriLQtkD+P4+aR75nKuDgYbFtpqSHWSkWrUe205xx5CoYtAd BMLKDW3vJ3hfcgCdcoaATGFOTlhFhiG3K63N36+nNZLoHXu5gSr4BIJQvuM8qmKhzPLlpL UIincmwjgtwnc+JVOytWCiHp2/xMIXr2XRsYwES3nPv5RVx8Rh/s7+7VaCd4MUmhKMzXCG O/29mOwQe41wFwTUwTdq64AQ9nB5OSXiCrXiRGk6b4Efi/+oIsXr1sSDT7HTfw== DKIM-Signature: v=1; a=ed25519-sha256; c=relaxed/relaxed; d=linutronix.de; s=2020e; t=1757534834; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:mime-version:mime-version:content-type:content-type: in-reply-to:in-reply-to:references:references; bh=TXiU2Y758Ana+gXTRNJ7cGEemsdXEpDtx+PeKTGcMqo=; b=WJb1KelVPWpq3gcmn+l2dHPcoeqYU3JdCmGEZUz0GVZlpx3Rvb+6OOlgAkTVC4Ei0v+GqJ Ja6q20EF7aLzHzCg== To: syzbot , anna-maria@linutronix.de, frederic@kernel.org, linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Cc: Peter Zijlstra , Juri Lelli Subject: Re: [syzbot] [kernel?] WARNING in hrtimer_forward (4) In-Reply-To: <68b25b42.a70a0220.1c57d1.00f6.GAE@google.com> References: <68b25b42.a70a0220.1c57d1.00f6.GAE@google.com> Date: Wed, 10 Sep 2025 22:07:13 +0200 Message-ID: <87qzwers0e.ffs@tglx> Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain On Fri, Aug 29 2025 at 19:00, syzbot wrote: > HEAD commit: b6add54ba618 Merge tag 'pinctrl-v6.17-2' of git://git.kern.. > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1130eef0580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=e1e1566c7726877e > dashboard link: https://syzkaller.appspot.com/bug?extid=8b3a2e23253b50098164 > compiler: Debian clang version 20.1.7 (++20250616065708+6146a88f6049-1~exp1~20250616065826.132), Debian LLD 20.1.7 > > Unfortunately, I don't have any reproducer for this issue yet. > > Downloadable assets: > disk image: https://storage.googleapis.com/syzbot-assets/102656909b6f/disk-b6add54b.raw.xz > vmlinux: https://storage.googleapis.com/syzbot-assets/fa30d1d80a47/vmlinux-b6add54b.xz > kernel image: https://storage.googleapis.com/syzbot-assets/c25ee8abf30a/bzImage-b6add54b.xz > > IMPORTANT: if you fix the issue, please add the following tag to the commit: > Reported-by: syzbot+8b3a2e23253b50098164@syzkaller.appspotmail.com > > ------------[ cut here ]------------ > WARNING: CPU: 1 PID: 1186 at kernel/time/hrtimer.c:1052 hrtimer_forward+0x1d6/0x2b0 kernel/time/hrtimer.c:1052 > Modules linked in: > CPU: 1 UID: 0 PID: 1186 Comm: irq/33-virtio1- Not tainted syzkaller #0 PREEMPT_{RT,(full)} > Hardware name: Google Google Compute Engine/Google Compute Engine, BIOS Google 07/12/2025 > RIP: 0010:hrtimer_forward+0x1d6/0x2b0 kernel/time/hrtimer.c:1052 It compains that the timer is enqueued when it is attempted to be forwarded > Code: 4c 89 33 48 8b 04 24 eb 07 e8 86 34 12 00 31 c0 48 83 c4 18 5b 41 5c 41 5d 41 5e 41 5f 5d e9 01 d8 4d 09 cc e8 6b 34 12 00 90 <0f> 0b 90 eb df 48 89 e8 4c 09 f8 48 c1 e8 20 74 0a 48 89 e8 31 d2 > RSP: 0018:ffffc90000a78bd0 EFLAGS: 00010006 > RAX: ffffffff81ac27e5 RBX: ffff8880b883b508 RCX: ffff888026c19dc0 > RDX: 0000000000000100 RSI: 0000000000010000 RDI: 0000000000010100 > RBP: 000000000009d057 R08: 0000000000010000 R09: 0000000000010100 > R10: dffffc0000000000 R11: ffffffff8167a890 R12: ffff8880b883b520 > R13: 0000000000184487 R14: 1ffff110171076a4 R15: 0000000000000001 > FS: 0000000000000000(0000) GS:ffff8881269c2000(0000) knlGS:0000000000000000 > CS: 0010 DS: 0000 ES: 0000 CR0: 0000000080050033 > CR2: 00007f95323cbf98 CR3: 0000000064088000 CR4: 00000000003526f0 > Call Trace: > > hrtimer_forward_now include/linux/hrtimer.h:366 [inline] > dl_server_timer kernel/sched/deadline.c:1193 [inline] which is strange as this is with the timer callback itself, so it shouldn't be enqueued, unless there is a possiblilty to have: CPU0 CPU1 timer_expires() callback() ???? dl_task_timer() rq_lock() rq_lock() hrtimer_start() rq_unlock() hrtimer_forward() No idea whether that's possible, but that's the only sensible explanation. > dl_task_timer+0xa42/0x12d0 kernel/sched/deadline.c:1234 > __run_hrtimer kernel/time/hrtimer.c:1761 [inline] > __hrtimer_run_queues+0x503/0xd40 kernel/time/hrtimer.c:1825 > hrtimer_interrupt+0x45d/0xa90 kernel/time/hrtimer.c:1887 > local_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1039 [inline] > __sysvec_apic_timer_interrupt+0x10b/0x410 arch/x86/kernel/apic/apic.c:1056 > instr_sysvec_apic_timer_interrupt arch/x86/kernel/apic/apic.c:1050 [inline] > sysvec_apic_timer_interrupt+0xa1/0xc0 arch/x86/kernel/apic/apic.c:1050 > > > asm_sysvec_apic_timer_interrupt+0x1a/0x20 arch/x86/include/asm/idtentry.h:702