From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from smtp153-163.sina.com.cn (smtp153-163.sina.com.cn [61.135.153.163]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id 0507441A8F for ; Wed, 3 Sep 2025 02:33:45 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=61.135.153.163 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756866835; cv=none; b=QzNA+kY4KxzRU0brfxTR/rKiti0x0H8C7rx36TRpWBdHNlcyHzxZf5ogDLzXKq3OpDfxp8WS3xTHSo8BlQF9NiUpt0kkfY/m8TWHEss43khGWj0JneRXpMZcszzu7iJuLFVFGDz4qkj9dJaeBhhXvSUsvIb5DTf3DoeyNPJmh/c= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1756866835; c=relaxed/simple; bh=6xZfxtcaUzl5/9Cm6wTgROkR0boDAFypzIxXKko+w9o=; h=From:To:Cc:Subject:Date:Message-ID:In-Reply-To:References: MIME-Version; b=P4CN6z+i5OmnLiGM1Bd24dyMHdVdGnAMzxM21gTsMPwtQhAomM0379Ghrw6RVEjFpxEBe4lJn+ZEu2h1sZT6hJ/+h7kFuppFunJpHUK5DT/KHWL6r/Cao9SRvOcan1I5JPNQE9PejvLE4L7DL3gA6Iu9+wq1IukRp3KOuc37UIY= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com; spf=pass smtp.mailfrom=sina.com; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b=dgpAtYmU; arc=none smtp.client-ip=61.135.153.163 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=sina.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=sina.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=sina.com header.i=@sina.com header.b="dgpAtYmU" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=sina.com; s=201208; t=1756866826; bh=nU9T5G15JS845jaGvFfo+n9HslrBJXYb/KPr7JZHe3k=; h=From:Subject:Date:Message-ID; b=dgpAtYmUXQDTCivW4AFqAyjGoHvgMsJOlKYnSeZsiFeboPkp3E1qzBn4OpTNzQ0Ak OzAZRbF6ZLOJMOYRXCppYOKHsMAMuCUOfTqA9gMtXGMYYjR78cisD1t3s3i/JuE3ND 8D3EnqAeppr5H9Z3lEmA/GxzmgzVnDn8v7C1Vwz0= X-SMAIL-HELO: localhost.localdomain Received: from unknown (HELO localhost.localdomain)([114.249.58.236]) by sina.com (10.54.253.32) with ESMTP id 68B7A8FE00007E03; Wed, 3 Sep 2025 10:33:36 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com Authentication-Results: sina.com; spf=none smtp.mailfrom=hdanton@sina.com; dkim=none header.i=none; dmarc=none action=none header.from=hdanton@sina.com X-SMAIL-MID: 4886904456632 X-SMAIL-UIID: 0E16182F2EF54347BF04119F51E20543-20250903-103336-1 From: Hillf Danton To: syzbot Cc: linux-kernel@vger.kernel.org, syzkaller-bugs@googlegroups.com Subject: Re: [syzbot] [block?] [mm?] INFO: rcu detected stall in wb_workfn (4) Date: Wed, 3 Sep 2025 10:33:25 +0800 Message-ID: <20250903023326.6389-1-hdanton@sina.com> In-Reply-To: <68b70218.050a0220.3db4df.01d1.GAE@google.com> References: Precedence: bulk X-Mailing-List: linux-kernel@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Transfer-Encoding: 8bit > Date: Tue, 02 Sep 2025 07:41:28 -0700 [thread overview] > syzbot has found a reproducer for the following issue on: > > HEAD commit: b320789d6883 Linux 6.17-rc4 > git tree: upstream > console output: https://syzkaller.appspot.com/x/log.txt?x=1406ae62580000 > kernel config: https://syzkaller.appspot.com/x/.config?x=d4703ac89d9e185a > dashboard link: https://syzkaller.appspot.com/bug?extid=5b4f4f81240931b16844 > compiler: gcc (Debian 12.2.0-14+deb12u1) 12.2.0, GNU ld (GNU Binutils for Debian) 2.40 > syz repro: https://syzkaller.appspot.com/x/repro.syz?x=133b5e34580000 > C reproducer: https://syzkaller.appspot.com/x/repro.c?x=1639ca42580000 #syz test upstream master --- x/kernel/rcu/tree_stall.h +++ y/kernel/rcu/tree_stall.h @@ -590,8 +590,15 @@ static void rcu_check_gp_kthread_starvat if (cpu_is_offline(cpu)) { pr_err("RCU GP kthread last ran on offline CPU %d.\n", cpu); } else if (!(data_race(READ_ONCE(rdp->mynode->qsmask)) & rdp->grpmask)) { + int i; pr_err("Stack dump where RCU GP kthread last ran:\n"); dump_cpu_task(cpu); + for_each_online_cpu(i) { + if (i == cpu) + continue; + pr_err("Stack dump on CPU%d\n", i); + dump_cpu_task(i); + } } wake_up_process(gpk); } --