From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from us-smtp-delivery-124.mimecast.com (us-smtp-delivery-124.mimecast.com [170.10.129.124]) (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 B5DAE2905 for ; Tue, 30 Jul 2024 03:15:34 +0000 (UTC) Authentication-Results: smtp.subspace.kernel.org; arc=none smtp.client-ip=170.10.129.124 ARC-Seal:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722309336; cv=none; b=ENgNcoQgX5Rbwq5ahA0kMCDVh5yKG9ndg4CEi1cqGSTKSZ3r3vowGiI2sVUOdAfoUOcsYJW705QdlYDQwesGvLmOpsujLqGdgBNpeapP0djJQESnunTxRugAsFN51MyyngLS3gZ02xG3hUQozqzqKAYAjY2h2qXcQzgd9VbkoBA= ARC-Message-Signature:i=1; a=rsa-sha256; d=subspace.kernel.org; s=arc-20240116; t=1722309336; c=relaxed/simple; bh=rHFV5LxTvCi8ppfT7h9UEuUOdoZOpakOV28TNR4w/Ww=; h=Message-ID:Date:MIME-Version:Subject:To:Cc:References:From: In-Reply-To:Content-Type; b=UClgCZBpdRKnlQQ8XupoZTL224vqMBDILm77ybdVL8DJjYeo+YvP0M8oRKOFaAAF7z0+qxPvDpsdPEgwMruA67oCpdQ9NJ6MgosQJRJVc+1yCBktJBsGTCib+CFj+r4U1wMKkwecC3KTv/9luyk3jBs/KorKk8jjeHmai9xL5g8= ARC-Authentication-Results:i=1; smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com; spf=pass smtp.mailfrom=redhat.com; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b=RCMA8po4; arc=none smtp.client-ip=170.10.129.124 Authentication-Results: smtp.subspace.kernel.org; dmarc=pass (p=none dis=none) header.from=redhat.com Authentication-Results: smtp.subspace.kernel.org; spf=pass smtp.mailfrom=redhat.com Authentication-Results: smtp.subspace.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="RCMA8po4" DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1722309333; 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: content-transfer-encoding:content-transfer-encoding: in-reply-to:in-reply-to:references:references; bh=xPcpg+QMPUVRrYNQm9FrtSfNfOo7KqJjD9nMBOe921k=; b=RCMA8po4vnVB+PaAHYRgBr61QC4S1zd4Z27hXBXlZNFaUqT7aKMZmFlcI4ZgQqVDgGUIHL ENeRzKZxgOpXbwl/hUo0caP/wutxAeucdhgO+b4gj0q7QC+Yd+k5TteuZuxgDnmg7v1C3s 0s9pDvQydQDpSmnQmhfXiGbqlx2BBIk= Received: from mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (ec2-54-186-198-63.us-west-2.compute.amazonaws.com [54.186.198.63]) by relay.mimecast.com with ESMTP with STARTTLS (version=TLSv1.3, cipher=TLS_AES_256_GCM_SHA384) id us-mta-213-tWu4k1AnPWehQSEfZfMTdg-1; Mon, 29 Jul 2024 23:15:21 -0400 X-MC-Unique: tWu4k1AnPWehQSEfZfMTdg-1 Received: from mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com [10.30.177.17]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits) server-digest SHA256) (No client certificate requested) by mx-prod-mc-04.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTPS id C32971955D44; Tue, 30 Jul 2024 03:15:18 +0000 (UTC) Received: from [10.2.16.36] (unknown [10.2.16.36]) by mx-prod-int-05.mail-002.prod.us-west-2.aws.redhat.com (Postfix) with ESMTP id A560D1955F40; Tue, 30 Jul 2024 03:15:16 +0000 (UTC) Message-ID: Date: Mon, 29 Jul 2024 23:15:15 -0400 Precedence: bulk X-Mailing-List: cgroups@vger.kernel.org List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 User-Agent: Mozilla Thunderbird Subject: Re: [PATCH] cgroup/cpuset: fix panic caused by partcmd_update To: chenridong , tj@kernel.org, lizefan.x@bytedance.com, hannes@cmpxchg.org, adityakali@google.com, sergeh@kernel.org Cc: bpf@vger.kernel.org, cgroups@vger.kernel.org, linux-kernel@vger.kernel.org References: <20240730015316.2324188-1-chenridong@huawei.com> <0ba00b7c-5292-4242-b648-4ca8d4a457c6@redhat.com> <425f1151-14e6-43f6-810e-efe95f6f401e@huawei.com> Content-Language: en-US From: Waiman Long In-Reply-To: <425f1151-14e6-43f6-810e-efe95f6f401e@huawei.com> Content-Type: text/plain; charset=UTF-8; format=flowed Content-Transfer-Encoding: 8bit X-Scanned-By: MIMEDefang 3.0 on 10.30.177.17 On 7/29/24 22:55, chenridong wrote: > > > On 2024/7/30 10:34, Waiman Long wrote: >> On 7/29/24 21:53, Chen Ridong wrote: >>> We find a bug as below: >>> BUG: unable to handle page fault for address: 00000003 >>> PGD 0 P4D 0 >>> Oops: 0000 [#1] PREEMPT SMP NOPTI >>> CPU: 3 PID: 358 Comm: bash Tainted: G        W I 6.6.0-10893-g60d6 >>> Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.15.0-1 >>> 04/4 >>> RIP: 0010:partition_sched_domains_locked+0x483/0x600 >>> Code: 01 48 85 d2 74 0d 48 83 05 29 3f f8 03 01 f3 48 0f bc c2 89 c0 >>> 48 9 >>> RSP: 0018:ffffc90000fdbc58 EFLAGS: 00000202 >>> RAX: 0000000100000003 RBX: ffff888100b3dfa0 RCX: 0000000000000000 >>> RDX: 0000000000000000 RSI: 0000000000000000 RDI: 000000000002fe80 >>> RBP: ffff888100b3dfb0 R08: 0000000000000001 R09: 0000000000000000 >>> R10: ffffc90000fdbcb0 R11: 0000000000000004 R12: 0000000000000002 >>> R13: ffff888100a92b48 R14: 0000000000000000 R15: 0000000000000000 >>> FS:  00007f44a5425740(0000) GS:ffff888237d80000(0000) >>> knlGS:0000000000000 >>> CS:  0010 DS: 0000 ES: 0000 CR0: 0000000080050033 >>> CR2: 0000000100030973 CR3: 000000010722c000 CR4: 00000000000006e0 >>> Call Trace: >>>   >>>   ? show_regs+0x8c/0xa0 >>>   ? __die_body+0x23/0xa0 >>>   ? __die+0x3a/0x50 >>>   ? page_fault_oops+0x1d2/0x5c0 >>>   ? partition_sched_domains_locked+0x483/0x600 >>>   ? search_module_extables+0x2a/0xb0 >>>   ? search_exception_tables+0x67/0x90 >>>   ? kernelmode_fixup_or_oops+0x144/0x1b0 >>>   ? __bad_area_nosemaphore+0x211/0x360 >>>   ? up_read+0x3b/0x50 >>>   ? bad_area_nosemaphore+0x1a/0x30 >>>   ? exc_page_fault+0x890/0xd90 >>>   ? __lock_acquire.constprop.0+0x24f/0x8d0 >>>   ? __lock_acquire.constprop.0+0x24f/0x8d0 >>>   ? asm_exc_page_fault+0x26/0x30 >>>   ? partition_sched_domains_locked+0x483/0x600 >>>   ? partition_sched_domains_locked+0xf0/0x600 >>>   rebuild_sched_domains_locked+0x806/0xdc0 >>>   update_partition_sd_lb+0x118/0x130 >>>   cpuset_write_resmask+0xffc/0x1420 >>>   cgroup_file_write+0xb2/0x290 >>>   kernfs_fop_write_iter+0x194/0x290 >>>   new_sync_write+0xeb/0x160 >>>   vfs_write+0x16f/0x1d0 >>>   ksys_write+0x81/0x180 >>>   __x64_sys_write+0x21/0x30 >>>   x64_sys_call+0x2f25/0x4630 >>>   do_syscall_64+0x44/0xb0 >>>   entry_SYSCALL_64_after_hwframe+0x78/0xe2 >>> RIP: 0033:0x7f44a553c887 >>> >>> It can be reproduced with cammands: >>> cd /sys/fs/cgroup/ >>> mkdir test >>> cd test/ >>> echo +cpuset > ../cgroup.subtree_control >>> echo root > cpuset.cpus.partition >>> echo 0-3 > cpuset.cpus // 3 is nproc >> What do you mean by "3 is nproc"? Are there only 3 CPUs in the >> system? What are the value of /sys/fs/cgroup/cpuset.cpu*? > Yes, I tested it with qemu, only 3 cpus are available. > # cat /sys/fs/cgroup/cpuset.cpus.effective > 0-3 > This case is taking all cpus away from root, test should fail to be a > valid root, it should not rebuild scheduling domains. I see. So there are 4 CPUs in the systems. So nproc should be 4. That is why I got confused when you said nproc is 3. I think you should clarify this in your patch. > >>> >>> This issue is caused by the incorrect rebuilding of scheduling domains. >>> In this scenario, test/cpuset.cpus.partition should be an invalid root >>> and should not trigger the rebuilding of scheduling domains. When >>> calling >>> update_parent_effective_cpumask with partcmd_update, if newmask is not >>> null, it should recheck newmask whether there are cpus is available >>> for parect/cs that has tasks. >>> >>> Fixes: 0c7f293efc87 ("cgroup/cpuset: Add >>> cpuset.cpus.exclusive.effective for v2") >>> Signed-off-by: Chen Ridong >>> --- >>>   kernel/cgroup/cpuset.c | 2 ++ >>>   1 file changed, 2 insertions(+) >>> >>> diff --git a/kernel/cgroup/cpuset.c b/kernel/cgroup/cpuset.c >>> index 40ec4abaf440..a9b6d56eeffa 100644 >>> --- a/kernel/cgroup/cpuset.c >>> +++ b/kernel/cgroup/cpuset.c >>> @@ -1991,6 +1991,8 @@ static int >>> update_parent_effective_cpumask(struct cpuset *cs, int cmd, >>>               part_error = PERR_CPUSEMPTY; >>>               goto write_error; >>>           } >>> +        /* Check newmask again, whether cpus are available for >>> parent/cs */ >>> +        nocpu |= tasks_nocpu_error(parent, cs, newmask); >>>           /* >>>            * partcmd_update with newmask: >> >> The code change looks reasonable to me. However, I would like to know >> more about the reproduction steps. I am OK with this patch other than missing some information in your reproduction step. Cheers, Longman