From nobody Mon Jun 8 05:24:56 2026 Received: from mail-oo1-f69.google.com (mail-oo1-f69.google.com [209.85.161.69]) (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 4BADC3FFFA7 for ; Fri, 5 Jun 2026 15:15:40 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=209.85.161.69 ARC-Seal: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780672541; cv=none; b=G6zpFvVhYdbPc7fn/RVep3VLqIA7ygs0cqc/L70RYX/OnYbxZBO49qucRZi5docZIlbLd2vniPM/zt9MiBaVrjQaGHXpFEIFuq0wNlQIuarOZYupMit4UQiYFsEFGWONmPj8w2MBQ3JtfvgN9QDiVLI2qzfGjdeGcn9jVFbC7o8= ARC-Message-Signature: i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1780672541; c=relaxed/simple; bh=42GB1GxVdq3Qyuw+w7CXIsyy93X1Bs9PH62AQcOG0qg=; h=MIME-Version:Date:In-Reply-To:Message-ID:Subject:From:To: Content-Type; b=WHnit+y47VhOdy150qr//D65urHF0PbcMuVBNUTOXhQES8EVHFToU1q9pfWat9/9vgtZRdlP+EhJ4ESvzFpc8bTlUcEhU7Eyw95vKmVLzdJjzQT++V35x3vBUcoZZN5HMkzkXcdZ87qSHBY0oDK2bagYzoyw7qgjvesPV87aeVY= 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=209.85.161.69 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-f69.google.com with SMTP id 006d021491bc7-69d85c328c7so1890661eaf.3 for ; Fri, 05 Jun 2026 08:15:39 -0700 (PDT) X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20251104; t=1780672539; x=1781277339; h=to:from:subject:message-id:in-reply-to:date:mime-version :x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=XNAHNrPO5T51xQ9HzflKlrlhTCyfi985O3GaF+76THo=; b=q/7WKbPs2/G+/VjMDJEf3z8qpzDgB6uLi3HIfJgakJL2IuPOoYGVLJLLdShsDBwZSM VEP8qlxFXo4Jt1LwujtjOWYwHUsGhJByX3AK+gHKxbm3ZSXUbGEDlCV61YnURK0hR+ev cqRIlt6sconRc4IT9nyyTVmEDLMDT6HaXcqXS8rmqCyYJl4j10A5sJCGlx8IEMvF8yXD M/0sw0Nwws8v3diF/um7S2SEgUy6o1SxE+vX1hw78Pmbefex9adqOiW3bIzq0oo9+c5v G85pBT/N6X4c/6a5OEgEuW6+OuEvwaXimBZtsq/Op92LFiZFUd4ijGjz0Z+R/CE5W/ox eAoA== X-Gm-Message-State: AOJu0YwaZ/PE+jlOwOIVy8Rrc8JORY3OuLcplXNTG+j8NkF9fHgvtWUa AzquEF66xCu7m2RSjwfViCykyyJa7UeJGA6vG5tAcrzjp8tKZ6q8DuIZnK80rpPzsL3zuLl2N9z F92R91UYk/pRqbSQzKAwpHoDHZSnYK9E7cGoG3RyOB6hcJCqZKgTr4qXPb6E= Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 X-Received: by 2002:a05:6820:1909:b0:69d:fb2c:77ff with SMTP id 006d021491bc7-69e68c18a26mr1986880eaf.30.1780672539273; Fri, 05 Jun 2026 08:15:39 -0700 (PDT) Date: Fri, 05 Jun 2026 08:15:39 -0700 In-Reply-To: <694f53ba.050a0220.35954c.0084.GAE@google.com> X-Google-Appengine-App-Id: s~syzkaller X-Google-Appengine-App-Id-Alias: syzkaller Message-ID: <6a22e81b.39669fcc.2372e3.0002.GAE@google.com> Subject: Forwarded: Re: [syzbot] [kvm?] [kvm-x86?] INFO: rcu detected stall in kvm_vcpu_ioctl (4) From: syzbot To: linux-kernel@vger.kernel.org Content-Transfer-Encoding: quoted-printable Content-Type: text/plain; charset="utf-8" For archival purposes, forwarding an incoming command email to linux-kernel@vger.kernel.org. *** Subject: Re: [syzbot] [kvm?] [kvm-x86?] INFO: rcu detected stall in kvm_vcp= u_ioctl (4) Author: clopez@suse.de #syz test: upstream master diff --git a/arch/x86/kvm/hyperv.c b/arch/x86/kvm/hyperv.c index 4438ecac9a89..d0e250d33ff0 100644 --- a/arch/x86/kvm/hyperv.c +++ b/arch/x86/kvm/hyperv.c @@ -626,6 +626,17 @@ static enum hrtimer_restart stimer_timer_callback(stru= ct hrtimer *timer) return HRTIMER_NORESTART; } =20 +/* + * Translate a stimer expiry given in 100 ns Hyper-V reference ticks into + * an absolute deadline. Saturates on overflow. + */ +static ktime_t stimer_add_delta(ktime_t now, u64 delta_100ns) +{ + if (delta_100ns > KTIME_MAX / 100) + return KTIME_MAX; + return ktime_add_safe(now, 100 * delta_100ns); +} + /* * stimer_start() assumptions: * a) stimer->count is not equal to 0 @@ -635,6 +646,7 @@ static int stimer_start(struct kvm_vcpu_hv_stimer *stim= er) { u64 time_now; ktime_t ktime_now; + ktime_t deadline; =20 time_now =3D get_time_ref_counter(hv_stimer_to_vcpu(stimer)->kvm); ktime_now =3D ktime_get(); @@ -657,10 +669,8 @@ static int stimer_start(struct kvm_vcpu_hv_stimer *sti= mer) stimer->index, time_now, stimer->exp_time); =20 - hrtimer_start(&stimer->timer, - ktime_add_ns(ktime_now, - 100 * (stimer->exp_time - time_now)), - HRTIMER_MODE_ABS); + deadline =3D stimer_add_delta(ktime_now, stimer->exp_time - time_now); + hrtimer_start(&stimer->timer, deadline, HRTIMER_MODE_ABS); return 0; } stimer->exp_time =3D stimer->count; @@ -679,9 +689,9 @@ static int stimer_start(struct kvm_vcpu_hv_stimer *stim= er) stimer->index, time_now, stimer->count); =20 - hrtimer_start(&stimer->timer, - ktime_add_ns(ktime_now, 100 * (stimer->count - time_now)), - HRTIMER_MODE_ABS); + deadline =3D stimer_add_delta(ktime_now, stimer->count - time_now); + hrtimer_start(&stimer->timer, deadline, HRTIMER_MODE_ABS); + return 0; }