Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751801AbcAAA6u (ORCPT ); Thu, 31 Dec 2015 19:58:50 -0500 Received: from h2.hallyn.com ([78.46.35.8]:48127 "EHLO h2.hallyn.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751179AbcAAA6s (ORCPT ); Thu, 31 Dec 2015 19:58:48 -0500 Date: Thu, 31 Dec 2015 18:58:43 -0600 From: "Serge E. Hallyn" To: Sergey Senozhatsky Cc: serge.hallyn@ubuntu.com, Stephen Rothwell , linux-api@vger.kernel.org, containers@lists.linux-foundation.org, hannes@cmpxchg.org, linux-kernel@vger.kernel.org, linux-next@vger.kernel.org, ebiederm@xmission.com, lxc-devel@lists.linuxcontainers.org, gregkh@linuxfoundation.org, tj@kernel.org, cgroups@vger.kernel.org, akpm@linux-foundation.org Subject: Re: [PATCH 6/8] cgroup: mount cgroupns-root when inside non-init cgroupns Message-ID: <20160101005843.GA26243@mail.hallyn.com> References: <1450844609-9194-1-git-send-email-serge.hallyn@ubuntu.com> <1450844609-9194-7-git-send-email-serge.hallyn@ubuntu.com> <20151231133822.GA463@swordfish> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20151231133822.GA463@swordfish> User-Agent: Mutt/1.5.21 (2010-09-15) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 4665 Lines: 112 On Thu, Dec 31, 2015 at 10:38:22PM +0900, Sergey Senozhatsky wrote: > On (12/22/15 22:23), serge.hallyn@ubuntu.com wrote: > [..] > > root = kzalloc(sizeof(*root), GFP_KERNEL); > > if (!root) { > > ret = -ENOMEM; > > @@ -2124,12 +2143,30 @@ out_free: > > kfree(opts.release_agent); > > kfree(opts.name); > > > > - if (ret) > > + if (ret) { > > + put_cgroup_ns(ns); > > return ERR_PTR(ret); > > + } > > out_mount: > > dentry = kernfs_mount(fs_type, flags, root->kf_root, > > is_v2 ? CGROUP2_SUPER_MAGIC : CGROUP_SUPER_MAGIC, > > &new_sb); > > + > > + /* > > + * In non-init cgroup namespace, instead of root cgroup's > > + * dentry, we return the dentry corresponding to the > > + * cgroupns->root_cgrp. > > + */ > > + if (!IS_ERR(dentry) && ns != &init_cgroup_ns) { > > + struct dentry *nsdentry; > > + struct cgroup *cgrp; > > + > > + cgrp = cset_cgroup_from_root(ns->root_cset, root); > > + nsdentry = kernfs_node_dentry(cgrp->kn, dentry->d_sb); > > + dput(dentry); > > + dentry = nsdentry; > > + } > > + > > if (IS_ERR(dentry) || !new_sb) > > cgroup_put(&root->cgrp); > > > > @@ -2142,6 +2179,7 @@ out_mount: > > deactivate_super(pinned_sb); > > } > > > > + put_cgroup_ns(ns); > > return dentry; > > } > > Hello, > > didn't investigate, just let you know that I'm seeing some warning on linux-next 20151231 > > 1159 is lockdep_assert_held(&css_set_lock) > > [ 2.880978] WARNING: CPU: 1 PID: 198 at kernel/cgroup.c:1159 cset_cgroup_from_root+0xa8/0xaf() > [ 2.880981] Modules linked in: mousedev arc4 nls_iso8859_1 nls_cp437 vfat fat serio_raw iwlmvm psmouse i915 atkbd mac80211 libps2 mxm_wmi i2c_algo_bit drm_kms_helper coretemp cfbfillrect iwlwifi syscopyarea hwmon cfbimgblt crc32c_intel sysfillrect sysimgblt fb_sys_fops cfg80211 ie31200_edac cfbcopyarea evdev r8169 lpc_ich drm i2c_i801 mii intel_gtt edac_core i2c_core mfd_core thermal video i8042 wmi serio button acpi_cpufreq ext4 crc16 mbcache jbd2 sd_mod ehci_pci ehci_hcd ahci libahci libata xhci_pci scsi_mod xhci_hcd usbcore usb_common > [ 2.881040] CPU: 1 PID: 198 Comm: kworker/1:2 Tainted: G W 4.4.0-rc7-next-20151231-dbg-00012-gc1e64b7-dirty #316 > [ 2.881045] Workqueue: events cgroup_release_agent > [ 2.881048] 0000000000000000 ffff88041b7f3cb8 ffffffff811e8bc6 0000000000000000 > [ 2.881053] ffff88041b7f3cf0 ffffffff81040889 ffffffff810b2d27 ffffffff8163f3c0 > [ 2.881057] ffff88041cc84000 ffff88041b7c0000 ffff88042fa58a00 ffff88041b7f3d00 > [ 2.881062] Call Trace: > [ 2.881068] [] dump_stack+0x4b/0x63 > [ 2.881073] [] warn_slowpath_common+0x99/0xb2 > [ 2.881076] [] ? cset_cgroup_from_root+0xa8/0xaf > [ 2.881080] [] warn_slowpath_null+0x1a/0x1c > [ 2.881083] [] cset_cgroup_from_root+0xa8/0xaf > [ 2.881086] [] cgroup_path+0x51/0x83 > [ 2.881090] [] cgroup_release_agent+0x75/0xed > [ 2.881094] [] process_one_work+0x292/0x54b > [ 2.881098] [] worker_thread+0x291/0x383 > [ 2.881102] [] ? rescuer_thread+0x2cf/0x2cf > [ 2.881105] [] kthread+0xf8/0x100 > [ 2.881108] [] ? kthread_create_on_node+0x1c7/0x1c7 > [ 2.881114] [] ret_from_fork+0x3f/0x70 > [ 2.881117] [] ? kthread_create_on_node+0x1c7/0x1c7 > [ 2.881119] ---[ end trace aa407df654d6b05d ]--- Thanks! Following trivial patch should fix this: >From fc54592077533ff2ff90ed54b72bf03b4378ca9f Mon Sep 17 00:00:00 2001 From: Serge Hallyn Date: Thu, 31 Dec 2015 16:55:19 -0800 Subject: [PATCH 1/1] cgroup_release_agent: grab css_set_lock around cgroup_path() Reported-by: Sergey Senozhatsky Signed-off-by: Serge Hallyn --- kernel/cgroup.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 4812f59..d10f127 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -5769,7 +5769,9 @@ static void cgroup_release_agent(struct work_struct *work) if (!pathbuf || !agentbuf) goto out; + spin_lock_bh(&css_set_lock); path = cgroup_path(cgrp, pathbuf, PATH_MAX); + spin_unlock_bh(&css_set_lock); if (!path) goto out; -- 2.5.0 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/