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2016-07-29Merge branch 'for-4.7-fixes' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull more cgroup updates from Tejun Heo: "I forgot to include the patches which got applied to for-4.7-fixes late during last cycle. Eric's three patches fix bugs introduced with the namespace support" * 'for-4.7-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroupns: Only allow creation of hierarchies in the initial cgroup namespace cgroupns: Close race between cgroup_post_fork and copy_cgroup_ns cgroupns: Fix the locking in copy_cgroup_ns
2016-07-27Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-nextLinus Torvalds
Pull networking updates from David Miller: 1) Unified UDP encapsulation offload methods for drivers, from Alexander Duyck. 2) Make DSA binding more sane, from Andrew Lunn. 3) Support QCA9888 chips in ath10k, from Anilkumar Kolli. 4) Several workqueue usage cleanups, from Bhaktipriya Shridhar. 5) Add XDP (eXpress Data Path), essentially running BPF programs on RX packets as soon as the device sees them, with the option to mirror the packet on TX via the same interface. From Brenden Blanco and others. 6) Allow qdisc/class stats dumps to run lockless, from Eric Dumazet. 7) Add VLAN support to b53 and bcm_sf2, from Florian Fainelli. 8) Simplify netlink conntrack entry layout, from Florian Westphal. 9) Add ipv4 forwarding support to mlxsw spectrum driver, from Ido Schimmel, Yotam Gigi, and Jiri Pirko. 10) Add SKB array infrastructure and convert tun and macvtap over to it. From Michael S Tsirkin and Jason Wang. 11) Support qdisc packet injection in pktgen, from John Fastabend. 12) Add neighbour monitoring framework to TIPC, from Jon Paul Maloy. 13) Add NV congestion control support to TCP, from Lawrence Brakmo. 14) Add GSO support to SCTP, from Marcelo Ricardo Leitner. 15) Allow GRO and RPS to function on macsec devices, from Paolo Abeni. 16) Support MPLS over IPV4, from Simon Horman. * git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next: (1622 commits) xgene: Fix build warning with ACPI disabled. be2net: perform temperature query in adapter regardless of its interface state l2tp: Correctly return -EBADF from pppol2tp_getname. net/mlx5_core/health: Remove deprecated create_singlethread_workqueue net: ipmr/ip6mr: update lastuse on entry change macsec: ensure rx_sa is set when validation is disabled tipc: dump monitor attributes tipc: add a function to get the bearer name tipc: get monitor threshold for the cluster tipc: make cluster size threshold for monitoring configurable tipc: introduce constants for tipc address validation net: neigh: disallow transition to NUD_STALE if lladdr is unchanged in neigh_update() MAINTAINERS: xgene: Add driver and documentation path Documentation: dtb: xgene: Add MDIO node dtb: xgene: Add MDIO node drivers: net: xgene: ethtool: Use phy_ethtool_gset and sset drivers: net: xgene: Use exported functions drivers: net: xgene: Enable MDIO driver drivers: net: xgene: Add backward compatibility drivers: net: phy: xgene: Add MDIO driver ...
2016-07-26Merge branch 'for-4.8' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup updates from Tejun Heo: "Nothing too exciting. - updates to the pids controller so that pid limit breaches can be noticed and monitored from userland. - cleanups and non-critical bug fixes" * 'for-4.8' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: remove duplicated include from cgroup.c cgroup: Use lld instead of ld when printing pids controller events_limit cgroup: Add pids controller event when fork fails because of pid limit cgroup: allow NULL return from ss->css_alloc() cgroup: remove unnecessary 0 check from css_from_id() cgroup: fix idr leak for the first cgroup root
2016-07-19cgroup: remove duplicated include from cgroup.cWei Yongjun
Remove duplicated include. Signed-off-by: Wei Yongjun <yongjun_wei@trendmicro.com.cn> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-07-15cgroupns: Only allow creation of hierarchies in the initial cgroup namespaceEric W. Biederman
Unprivileged users can't use hierarchies if they create them as they do not have privilieges to the root directory. Which means the only thing a hiearchy created by an unprivileged user is good for is expanding the number of cgroup links in every css_set, which is a DOS attack. We could allow hierarchies to be created in namespaces in the initial user namespace. Unfortunately there is only a single namespace for the names of heirarchies, so that is likely to create more confusion than not. So do the simple thing and restrict hiearchy creation to the initial cgroup namespace. Cc: stable@vger.kernel.org Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-07-15cgroupns: Close race between cgroup_post_fork and copy_cgroup_nsEric W. Biederman
In most code paths involving cgroup migration cgroup_threadgroup_rwsem is taken. There are two exceptions: - remove_tasks_in_empty_cpuset calls cgroup_transfer_tasks - vhost_attach_cgroups_work calls cgroup_attach_task_all With cgroup_threadgroup_rwsem held it is guaranteed that cgroup_post_fork and copy_cgroup_ns will reference the same css_set from the process calling fork. Without such an interlock there process after fork could reference one css_set from it's new cgroup namespace and another css_set from task->cgroups, which semantically is nonsensical. Cc: stable@vger.kernel.org Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-07-15cgroupns: Fix the locking in copy_cgroup_nsEric W. Biederman
If "clone(CLONE_NEWCGROUP...)" is called it results in a nice lockdep valid splat. In __cgroup_proc_write the lock ordering is: cgroup_mutex -- through cgroup_kn_lock_live cgroup_threadgroup_rwsem In copy_process the guts of clone the lock ordering is: cgroup_threadgroup_rwsem -- through threadgroup_change_begin cgroup_mutex -- through copy_namespaces -- copy_cgroup_ns lockdep reports some a different call chains for the first ordering of cgroup_mutex and cgroup_threadgroup_rwsem but it is harder to trace. This is most definitely deadlock potential under the right circumstances. Fix this by by skipping the cgroup_mutex and making the locking in copy_cgroup_ns mirror the locking in cgroup_post_fork which also runs during fork under the cgroup_threadgroup_rwsem. Cc: stable@vger.kernel.org Fixes: a79a908fd2b0 ("cgroup: introduce cgroup namespaces") Signed-off-by: "Eric W. Biederman" <ebiederm@xmission.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-07-01cgroup: Add cgroup_get_from_fdMartin KaFai Lau
Add a helper function to get a cgroup2 from a fd. It will be stored in a bpf array (BPF_MAP_TYPE_CGROUP_ARRAY) which will be introduced in the later patch. Signed-off-by: Martin KaFai Lau <kafai@fb.com> Cc: Alexei Starovoitov <ast@fb.com> Cc: Daniel Borkmann <daniel@iogearbox.net> Cc: Tejun Heo <tj@kernel.org> Acked-by: Tejun Heo <tj@kernel.org> Signed-off-by: David S. Miller <davem@davemloft.net>
2016-06-23cgroup: Disable IRQs while holding css_set_lockDaniel Bristot de Oliveira
While testing the deadline scheduler + cgroup setup I hit this warning. [ 132.612935] ------------[ cut here ]------------ [ 132.612951] WARNING: CPU: 5 PID: 0 at kernel/softirq.c:150 __local_bh_enable_ip+0x6b/0x80 [ 132.612952] Modules linked in: (a ton of modules...) [ 132.612981] CPU: 5 PID: 0 Comm: swapper/5 Not tainted 4.7.0-rc2 #2 [ 132.612981] Hardware name: QEMU Standard PC (i440FX + PIIX, 1996), BIOS 1.8.2-20150714_191134- 04/01/2014 [ 132.612982] 0000000000000086 45c8bb5effdd088b ffff88013fd43da0 ffffffff813d229e [ 132.612984] 0000000000000000 0000000000000000 ffff88013fd43de0 ffffffff810a652b [ 132.612985] 00000096811387b5 0000000000000200 ffff8800bab29d80 ffff880034c54c00 [ 132.612986] Call Trace: [ 132.612987] <IRQ> [<ffffffff813d229e>] dump_stack+0x63/0x85 [ 132.612994] [<ffffffff810a652b>] __warn+0xcb/0xf0 [ 132.612997] [<ffffffff810e76a0>] ? push_dl_task.part.32+0x170/0x170 [ 132.612999] [<ffffffff810a665d>] warn_slowpath_null+0x1d/0x20 [ 132.613000] [<ffffffff810aba5b>] __local_bh_enable_ip+0x6b/0x80 [ 132.613008] [<ffffffff817d6c8a>] _raw_write_unlock_bh+0x1a/0x20 [ 132.613010] [<ffffffff817d6c9e>] _raw_spin_unlock_bh+0xe/0x10 [ 132.613015] [<ffffffff811388ac>] put_css_set+0x5c/0x60 [ 132.613016] [<ffffffff8113dc7f>] cgroup_free+0x7f/0xa0 [ 132.613017] [<ffffffff810a3912>] __put_task_struct+0x42/0x140 [ 132.613018] [<ffffffff810e776a>] dl_task_timer+0xca/0x250 [ 132.613027] [<ffffffff810e76a0>] ? push_dl_task.part.32+0x170/0x170 [ 132.613030] [<ffffffff8111371e>] __hrtimer_run_queues+0xee/0x270 [ 132.613031] [<ffffffff81113ec8>] hrtimer_interrupt+0xa8/0x190 [ 132.613034] [<ffffffff81051a58>] local_apic_timer_interrupt+0x38/0x60 [ 132.613035] [<ffffffff817d9b0d>] smp_apic_timer_interrupt+0x3d/0x50 [ 132.613037] [<ffffffff817d7c5c>] apic_timer_interrupt+0x8c/0xa0 [ 132.613038] <EOI> [<ffffffff81063466>] ? native_safe_halt+0x6/0x10 [ 132.613043] [<ffffffff81037a4e>] default_idle+0x1e/0xd0 [ 132.613044] [<ffffffff810381cf>] arch_cpu_idle+0xf/0x20 [ 132.613046] [<ffffffff810e8fda>] default_idle_call+0x2a/0x40 [ 132.613047] [<ffffffff810e92d7>] cpu_startup_entry+0x2e7/0x340 [ 132.613048] [<ffffffff81050235>] start_secondary+0x155/0x190 [ 132.613049] ---[ end trace f91934d162ce9977 ]--- The warn is the spin_(lock|unlock)_bh(&css_set_lock) in the interrupt context. Converting the spin_lock_bh to spin_lock_irq(save) to avoid this problem - and other problems of sharing a spinlock with an interrupt. Cc: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Juri Lelli <juri.lelli@arm.com> Cc: Steven Rostedt <rostedt@goodmis.org> Cc: cgroups@vger.kernel.org Cc: stable@vger.kernel.org # 4.5+ Cc: linux-kernel@vger.kernel.org Reviewed-by: Rik van Riel <riel@redhat.com> Reviewed-by: "Luis Claudio R. Goncalves" <lgoncalv@redhat.com> Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com> Acked-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-06-21cgroup: allow NULL return from ss->css_alloc()Tejun Heo
cgroup core expected css_alloc to return an ERR_PTR value on failure and caused NULL deref if it returned NULL. It's an easy mistake to make from an alloc function and there's no ambiguity in what's being indicated. Update css_create() so that it interprets NULL return from css_alloc as -ENOMEM. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-06-17cgroup: remove unnecessary 0 check from css_from_id()Johannes Weiner
css_idr allocation starts at 1, so index 0 will never point to an item. css_from_id() currently filters that before asking idr_find(), but idr_find() would also just return NULL, so this is not needed. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-06-17cgroup: fix idr leak for the first cgroup rootJohannes Weiner
The valid cgroup hierarchy ID range includes 0, so we can't filter for positive numbers when freeing it, or it'll leak the first ID. No big deal, just disruptive when reading the code. The ID is freed during error handling and when the reference count hits zero, so the double-free test is not necessary; remove it. Signed-off-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-06-16cgroup: set css->id to -1 during initTejun Heo
If percpu_ref initialization fails during css_create(), the free path can end up trying to free css->id of zero. As ID 0 is unused, it doesn't cause a critical breakage but it does trigger a warning message. Fix it by setting css->id to -1 from init_and_link_css(). Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Wenwei Tao <ww.tao0320@gmail.com> Fixes: 01e586598b22 ("cgroup: release css->id after css_free") Cc: stable@vger.kernel.org # v4.0+ Signed-off-by: Tejun Heo <tj@kernel.org>
2016-05-26cgroup: remove redundant cleanup in css_createWenwei Tao
When create css failed, before call css_free_rcu_fn, we remove the css id and exit the percpu_ref, but we will do these again in css_free_work_fn, so they are redundant. Especially the css id, that would cause problem if we remove it twice, since it may be assigned to another css after the first remove. tj: This was broken by two commits updating the free path without synchronizing the creation failure path. This can be easily triggered by trying to create more than 64k memory cgroups. Signed-off-by: Wenwei Tao <ww.tao0320@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Vladimir Davydov <vdavydov@parallels.com> Fixes: 9a1049da9bd2 ("percpu-refcount: require percpu_ref to be exited explicitly") Fixes: 01e586598b22 ("cgroup: release css->id after css_free") Cc: stable@vger.kernel.org # v3.17+
2016-05-12cgroup: fix compile warningFelipe Balbi
commit 4f41fc59620f ("cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces") added the following compile warning: kernel/cgroup.c: In function ‘cgroup_show_path’: kernel/cgroup.c:1634:15: warning: unused variable ‘ret’ [-Wunused-variable] int len = 0, ret = 0; ^ fix it. Fixes: 4f41fc59620f ("cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespaces") Signed-off-by: Felipe Balbi <felipe.balbi@linux.intel.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-05-09cgroup, kernfs: make mountinfo show properly scoped path for cgroup namespacesSerge E. Hallyn
Patch summary: When showing a cgroupfs entry in mountinfo, show the path of the mount root dentry relative to the reader's cgroup namespace root. Short explanation (courtesy of mkerrisk): If we create a new cgroup namespace, then we want both /proc/self/cgroup and /proc/self/mountinfo to show cgroup paths that are correctly virtualized with respect to the cgroup mount point. Previous to this patch, /proc/self/cgroup shows the right info, but /proc/self/mountinfo does not. Long version: When a uid 0 task which is in freezer cgroup /a/b, unshares a new cgroup namespace, and then mounts a new instance of the freezer cgroup, the new mount will be rooted at /a/b. The root dentry field of the mountinfo entry will show '/a/b'. cat > /tmp/do1 << EOF mount -t cgroup -o freezer freezer /mnt grep freezer /proc/self/mountinfo EOF unshare -Gm bash /tmp/do1 > 330 160 0:34 / /sys/fs/cgroup/freezer rw,nosuid,nodev,noexec,relatime - cgroup cgroup rw,freezer > 355 133 0:34 /a/b /mnt rw,relatime - cgroup freezer rw,freezer The task's freezer cgroup entry in /proc/self/cgroup will simply show '/': grep freezer /proc/self/cgroup 9:freezer:/ If instead the same task simply bind mounts the /a/b cgroup directory, the resulting mountinfo entry will again show /a/b for the dentry root. However in this case the task will find its own cgroup at /mnt/a/b, not at /mnt: mount --bind /sys/fs/cgroup/freezer/a/b /mnt 130 25 0:34 /a/b /mnt rw,nosuid,nodev,noexec,relatime shared:21 - cgroup cgroup rw,freezer In other words, there is no way for the task to know, based on what is in mountinfo, which cgroup directory is its own. Example (by mkerrisk): First, a little script to save some typing and verbiage: echo -e "\t/proc/self/cgroup:\t$(cat /proc/self/cgroup | grep freezer)" cat /proc/self/mountinfo | grep freezer | awk '{print "\tmountinfo:\t\t" $4 "\t" $5}' Create cgroup, place this shell into the cgroup, and look at the state of the /proc files: 2653 2653 # Our shell 14254 # cat(1) /proc/self/cgroup: 10:freezer:/a/b mountinfo: / /sys/fs/cgroup/freezer Create a shell in new cgroup and mount namespaces. The act of creating a new cgroup namespace causes the process's current cgroups directories to become its cgroup root directories. (Here, I'm using my own version of the "unshare" utility, which takes the same options as the util-linux version): Look at the state of the /proc files: /proc/self/cgroup: 10:freezer:/ mountinfo: / /sys/fs/cgroup/freezer The third entry in /proc/self/cgroup (the pathname of the cgroup inside the hierarchy) is correctly virtualized w.r.t. the cgroup namespace, which is rooted at /a/b in the outer namespace. However, the info in /proc/self/mountinfo is not for this cgroup namespace, since we are seeing a duplicate of the mount from the old mount namespace, and the info there does not correspond to the new cgroup namespace. However, trying to create a new mount still doesn't show us the right information in mountinfo: # propagating to other mountns /proc/self/cgroup: 7:freezer:/ mountinfo: /a/b /mnt/freezer The act of creating a new cgroup namespace caused the process's current freezer directory, "/a/b", to become its cgroup freezer root directory. In other words, the pathname directory of the directory within the newly mounted cgroup filesystem should be "/", but mountinfo wrongly shows us "/a/b". The consequence of this is that the process in the cgroup namespace cannot correctly construct the pathname of its cgroup root directory from the information in /proc/PID/mountinfo. With this patch, the dentry root field in mountinfo is shown relative to the reader's cgroup namespace. So the same steps as above: /proc/self/cgroup: 10:freezer:/a/b mountinfo: / /sys/fs/cgroup/freezer /proc/self/cgroup: 10:freezer:/ mountinfo: /../.. /sys/fs/cgroup/freezer /proc/self/cgroup: 10:freezer:/ mountinfo: / /mnt/freezer cgroup.clone_children freezer.parent_freezing freezer.state tasks cgroup.procs freezer.self_freezing notify_on_release 3164 2653 # First shell that placed in this cgroup 3164 # Shell started by 'unshare' 14197 # cat(1) Signed-off-by: Serge Hallyn <serge.hallyn@ubuntu.com> Tested-by: Michael Kerrisk <mtk.manpages@gmail.com> Acked-by: Michael Kerrisk <mtk.manpages@gmail.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-04-25cgroup, cpuset: replace cpuset_post_attach_flush() with ↵Tejun Heo
cgroup_subsys->post_attach callback Since e93ad19d0564 ("cpuset: make mm migration asynchronous"), cpuset kicks off asynchronous NUMA node migration if necessary during task migration and flushes it from cpuset_post_attach_flush() which is called at the end of __cgroup_procs_write(). This is to avoid performing migration with cgroup_threadgroup_rwsem write-locked which can lead to deadlock through dependency on kworker creation. memcg has a similar issue with charge moving, so let's convert it to an official callback rather than the current one-off cpuset specific function. This patch adds cgroup_subsys->post_attach callback and makes cpuset register cpuset_post_attach_flush() as its ->post_attach. The conversion is mostly one-to-one except that the new callback is called under cgroup_mutex. This is to guarantee that no other migration operations are started before ->post_attach callbacks are finished. cgroup_mutex is one of the outermost mutex in the system and has never been and shouldn't be a problem. We can add specialized synchronization around __cgroup_procs_write() but I don't think there's any noticeable benefit. Signed-off-by: Tejun Heo <tj@kernel.org> Cc: Li Zefan <lizefan@huawei.com> Cc: Johannes Weiner <hannes@cmpxchg.org> Cc: Michal Hocko <mhocko@kernel.org> Cc: <stable@vger.kernel.org> # 4.4+ prerequisite for the next patch
2016-03-21Merge branch 'for-4.6-ns' of ↵Linus Torvalds
git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup Pull cgroup namespace support from Tejun Heo: "These are changes to implement namespace support for cgroup which has been pending for quite some time now. It is very straight-forward and only affects what part of cgroup hierarchies are visible. After unsharing, mounting a cgroup fs will be scoped to the cgroups the task belonged to at the time of unsharing and the cgroup paths exposed to userland would be adjusted accordingly" * 'for-4.6-ns' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: fix and restructure error handling in copy_cgroup_ns() cgroup: fix alloc_cgroup_ns() error handling in copy_cgroup_ns() Add FS_USERNS_FLAG to cgroup fs cgroup: Add documentation for cgroup namespaces cgroup: mount cgroupns-root when inside non-init cgroupns kernfs: define kernfs_node_dentry cgroup: cgroup namespace setns support cgroup: introduce cgroup namespaces sched: new clone flag CLONE_NEWCGROUP for cgroup namespace kernfs: Add API to generate relative kernfs path
2016-03-16cgroup: avoid false positive gcc-6 warningArnd Bergmann
When all subsystems are disabled, gcc notices that cgroup_subsys_enabled_key is a zero-length array and that any access to it must be out of bounds: In file included from ../include/linux/cgroup.h:19:0, from ../kernel/cgroup.c:31: ../kernel/cgroup.c: In function 'cgroup_add_cftypes': ../kernel/cgroup.c:261:53: error: array subscript is above array bounds [-Werror=array-bounds] return static_key_enabled(cgroup_subsys_enabled_key[ssid]); ~~~~~~~~~~~~~~~~~~~~~~~~~^~~~~~ ../include/linux/jump_label.h:271:40: note: in definition of macro 'static_key_enabled' static_key_count((struct static_key *)x) > 0; \ ^ We should never call the function in this particular case, so this is not a bug. In order to silence the warning, this adds an explicit check for the CGROUP_SUBSYS_COUNT==0 case. Signed-off-by: Arnd Bergmann <arnd@arndb.de> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-16cgroup: ignore css_sets associated with dead cgroups during migrationTejun Heo
Before 2e91fa7f6d45 ("cgroup: keep zombies associated with their original cgroups"), all dead tasks were associated with init_css_set. If a zombie task is requested for migration, while migration prep operations would still be performed on init_css_set, the actual migration would ignore zombie tasks. As init_css_set is always valid, this worked fine. However, after 2e91fa7f6d45, zombie tasks stay with the css_set it was associated with at the time of death. Let's say a task T associated with cgroup A on hierarchy H-1 and cgroup B on hiearchy H-2. After T becomes a zombie, it would still remain associated with A and B. If A only contains zombie tasks, it can be removed. On removal, A gets marked offline but stays pinned until all zombies are drained. At this point, if migration is initiated on T to a cgroup C on hierarchy H-2, migration path would try to prepare T's css_set for migration and trigger the following. WARNING: CPU: 0 PID: 1576 at kernel/cgroup.c:474 cgroup_get+0x121/0x160() CPU: 0 PID: 1576 Comm: bash Not tainted 4.4.0-work+ #289 ... Call Trace: [<ffffffff8127e63c>] dump_stack+0x4e/0x82 [<ffffffff810445e8>] warn_slowpath_common+0x78/0xb0 [<ffffffff810446d5>] warn_slowpath_null+0x15/0x20 [<ffffffff810c33e1>] cgroup_get+0x121/0x160 [<ffffffff810c349b>] link_css_set+0x7b/0x90 [<ffffffff810c4fbc>] find_css_set+0x3bc/0x5e0 [<ffffffff810c5269>] cgroup_migrate_prepare_dst+0x89/0x1f0 [<ffffffff810c7547>] cgroup_attach_task+0x157/0x230 [<ffffffff810c7a17>] __cgroup_procs_write+0x2b7/0x470 [<ffffffff810c7bdc>] cgroup_tasks_write+0xc/0x10 [<ffffffff810c4790>] cgroup_file_write+0x30/0x1b0 [<ffffffff811c68fc>] kernfs_fop_write+0x13c/0x180 [<ffffffff81151673>] __vfs_write+0x23/0xe0 [<ffffffff81152494>] vfs_write+0xa4/0x1a0 [<ffffffff811532d4>] SyS_write+0x44/0xa0 [<ffffffff814af2d7>] entry_SYSCALL_64_fastpath+0x12/0x6f It doesn't make sense to prepare migration for css_sets pointing to dead cgroups as they are guaranteed to contain only zombies which are ignored later during migration. This patch makes cgroup destruction path mark all affected css_sets as dead and updates the migration path to ignore them during preparation. Signed-off-by: Tejun Heo <tj@kernel.org> Fixes: 2e91fa7f6d45 ("cgroup: keep zombies associated with their original cgroups") Cc: stable@vger.kernel.org # v4.4+
2016-03-08cgroup: implement cgroup_subsys->implicit_on_dflTejun Heo
Some controllers, perf_event for now and possibly freezer in the future, don't really make sense to control explicitly through "cgroup.subtree_control". For example, the primary role of perf_event is identifying the cgroups of tasks; however, because the controller also keeps a small amount of state per cgroup, it can't be replaced with simple cgroup membership tests. This patch implements cgroup_subsys->implicit_on_dfl flag. When set, the controller is implicitly enabled on all cgroups on the v2 hierarchy so that utility type controllers such as perf_event can be enabled and function transparently. An implicit controller doesn't show up in "cgroup.controllers" or "cgroup.subtree_control", is exempt from no internal process rule and can be stolen from the default hierarchy even if there are non-root csses. v2: Reimplemented on top of the recent updates to css handling and subsystem rebinding. Rebinding implicit subsystems is now a simple matter of exempting it from the busy subsystem check. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-08cgroup: use css_set->mg_dst_cgrp for the migration target cgroupTejun Heo
Migration can be multi-target on the default hierarchy when a controller is enabled - processes belonging to each child cgroup have to be moved to the child cgroup itself to refresh css association. This isn't a problem for cgroup_migrate_add_src() as each source css_set still maps to single source and target cgroups; however, cgroup_migrate_prepare_dst() is called once after all source css_sets are added and thus might not have a single destination cgroup. This is currently worked around by specifying NULL for @dst_cgrp and using the source's default cgroup as destination as the only multi-target migration in use is self-targetting. While this works, it's subtle and clunky. As all taget cgroups are already specified while preparing the source css_sets, this clunkiness can easily be removed by recording the target cgroup in each source css_set. This patch adds css_set->mg_dst_cgrp which is recorded on cgroup_migrate_src() and used by cgroup_migrate_prepare_dst(). This also makes migration code ready for arbitrary multi-target migration. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-08cgroup: make cgroup[_taskset]_migrate() take cgroup_root instead of cgroupTejun Heo
On the default hierarchy, a migration can be multi-source and/or multi-destination. cgroup_taskest_migrate() used to incorrectly assume single destination cgroup but the bug has been fixed by 1f7dd3e5a6e4 ("cgroup: fix handling of multi-destination migration from subtree_control enabling"). Since the commit, @dst_cgrp to cgroup[_taskset]_migrate() is only used to determine which subsystems are affected or which cgroup_root the migration is taking place in. As such, @dst_cgrp is misleading. This patch replaces @dst_cgrp with @root. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-08cgroup: move migration destination verification out of ↵Tejun Heo
cgroup_migrate_prepare_dst() cgroup_migrate_prepare_dst() verifies whether the destination cgroup is allowable; however, the test doesn't really belong there. It's too deep and common in the stack and as a result the test itself is gated by another test. Separate the test out into cgroup_may_migrate_to() and update cgroup_attach_task() and cgroup_transfer_tasks() to perform the test directly. This doesn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-08cgroup: fix incorrect destination cgroup in cgroup_update_dfl_csses()Tejun Heo
cgroup_update_dfl_csses() should move each task in the subtree to self; however, it was incorrectly calling cgroup_migrate_add_src() with the root of the subtree as @dst_cgrp. Fortunately, cgroup_migrate_add_src() currently uses @dst_cgrp only to determine the hierarchy and the bug doesn't cause any actual breakages. Fix it. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-03-03cgroup: update css iteration in cgroup_update_dfl_csses()Tejun Heo
The existing sequences of operations ensure that the offlining csses are drained before cgroup_update_dfl_csses(), so even though cgroup_update_dfl_csses() uses css_for_each_descendant_pre() to walk the target cgroups, it doesn't end up operating on dead cgroups. Also, the function explicitly excludes the subtree root from operation. This is fragile and inconsistent with the rest of css update operations. This patch updates cgroup_update_dfl_csses() to use cgroup_for_each_live_descendant_pre() instead and include the subtree root. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: allocate 2x cgrp_cset_links when setting up a new rootTejun Heo
During prep, cgroup_setup_root() allocates cgrp_cset_links matching the number of existing css_sets to later link the new root. This is fine for now as the only operation which can happen inbetween is rebind_subsystems() and rebinding of empty subsystems doesn't create new css_sets. However, while not yet allowed, with the recent reimplementation, rebind_subsystems() can rebind subsystems with descendant csses and thus can create new css_sets. This patch makes cgroup_setup_root() allocate 2x of the existing css_sets so that later use of live subsystem rebinding doesn't blow up. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: make cgroup_calc_subtree_ss_mask() take @this_ss_maskTejun Heo
cgroup_calc_subtree_ss_mask() currently takes @cgrp and @subtree_control. @cgrp is used for two purposes - to decide whether it's for default hierarchy and the mask of available subsystems. The former doesn't matter as the results are the same regardless. The latter can be specified directly through a subsystem mask. This patch makes cgroup_calc_subtree_ss_mask() perform the same calculations for both default and legacy hierarchies and take @this_ss_mask for available subsystems. @cgrp is no longer used and dropped. This is to allow using the function in contexts where available controllers can't be decided from the cgroup. v2: cgroup_refres_subtree_ss_mask() is removed by a previous patch. Updated accordingly. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: reimplement rebind_subsystems() using cgroup_apply_control() and friendsTejun Heo
rebind_subsystem() open codes quite a bit of css and interface file manipulations. It tries to be fail-safe but doesn't quite achieve it. It can be greatly simplified by using the new css management helpers. This patch reimplements rebind_subsytsems() using cgroup_apply_control() and friends. * The half-baked rollback on file creation failure is dropped. It is an extremely cold path, failure isn't critical, and, aside from kernel bugs, the only reason it can fail is memory allocation failure which pretty much doesn't happen for small allocations. * As cgroup_apply_control_disable() is now used to clean up root cgroup on rebind, make sure that it doesn't end up killing root csses. * All callers of rebind_subsystems() are updated to use cgroup_lock_and_drain_offline() as the apply_control functions require drained subtree. * This leaves cgroup_refresh_subtree_ss_mask() without any user. Removed. * css_populate_dir() and css_clear_dir() no longer needs @cgrp_override parameter. Dropped. * While at it, add WARN_ON() to rebind_subsystem() calls which are expected to always succeed just in case. While the rules visible to userland aren't changed, this reimplementation not only simplifies rebind_subsystems() but also allows it to disable and enable csses recursively. This can be used to implement more flexible rebinding. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: use cgroup_apply_enable_control() in cgroup creation pathTejun Heo
cgroup_create() manually updates control masks and creates child csses which cgroup_mkdir() then manually populates. Both can be simplified by using cgroup_apply_enable_control() and friends. The only catch is that it calls css_populate_dir() with NULL cgroup->kn during cgroup_create(). This is worked around by making the function noop on NULL kn. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: combine cgroup_mutex locking and offline css drainingTejun Heo
cgroup_drain_offline() is used to wait for csses being offlined to uninstall itself from cgroup->subsys[] array so that new csses can be installed. The function's only user, cgroup_subtree_control_write(), calls it after performing some checks and restarts the whole process via restart_syscall() if draining has to release cgroup_mutex to wait. This can be simplified by draining before other synchronized operations so that there's nothing to restart. This patch converts cgroup_drain_offline() to cgroup_lock_and_drain_offline() which performs both locking and draining and updates cgroup_kn_lock_live() use it instead of cgroup_mutex() if requested. This combined locking and draining operations are easier to use and less error-prone. While at it, add WARNs in control_apply functions which triggers if the subtree isn't properly drained. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: factor out cgroup_{apply|finalize}_control() from ↵Tejun Heo
cgroup_subtree_control_write() Factor out cgroup_{apply|finalize}_control() so that control mask update can be done in several simple steps. This patch doesn't introduce behavior changes. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: introduce cgroup_{save|propagate|restore}_control()Tejun Heo
While controllers are being enabled and disabled in cgroup_subtree_control_write(), the original subsystem masks are stashed in local variables so that they can be restored if the operation fails in the middle. This patch adds dedicated fields to struct cgroup to be used instead of the local variables and implements functions to stash the current values, propagate the changes and restore them recursively. Combined with the previous changes, this makes subsystem management operations fully recursive and modularlized. This will be used to expand cgroup core functionalities. While at it, remove now unused @css_enable and @css_disable from cgroup_subtree_control_write(). Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: make cgroup_drain_offline() and ↵Tejun Heo
cgroup_apply_control_{disable|enable}() recursive The three factored out css management operations - cgroup_drain_offline() and cgroup_apply_control_{disable|enable}() - only depend on the current state of the target cgroups and idempotent and thus can be easily made to operate on the subtree instead of the immediate children. This patch introduces the iterators which walk live subtree and converts the three functions to operate on the subtree including self instead of the children. While this leads to spurious walking and be slightly more expensive, it will allow them to be used for wider scope of operations. Note that cgroup_drain_offline() now tests for whether a css is dying before trying to drain it. This is to avoid trying to drain live csses as there can be mix of live and dying csses in a subtree unlike children of the same parent. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: factor out cgroup_apply_control_enable() from ↵Tejun Heo
cgroup_subtree_control_write() Factor out css enabling and showing into cgroup_apply_control_enable(). * Nest subsystem walk inside child walk. The child walk will later be converted to subtree walk which is a bit more expensive. * Instead of operating on the differential masks @css_enable, simply enable or show csses according to the current cgroup_control() and cgroup_ss_mask(). This leads to the same result and is simpler and more robust. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: factor out cgroup_apply_control_disable() from ↵Tejun Heo
cgroup_subtree_control_write() Factor out css disabling and hiding into cgroup_apply_control_disable(). * Nest subsystem walk inside child walk. The child walk will later be converted to subtree walk which is a bit more expensive. * Instead of operating on the differential masks @css_enable and @css_disable, simply disable or hide csses according to the current cgroup_control() and cgroup_ss_mask(). This leads to the same result and is simpler and more robust. * This allows error handling path to share the same code. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: factor out cgroup_drain_offline() from cgroup_subtree_control_write()Tejun Heo
Factor out async css offline draining into cgroup_drain_offline(). * Nest subsystem walk inside child walk. The child walk will later be converted to subtree walk which is a bit more expensive. * Relocate the draining above subsystem mask preparation, which doesn't create any behavior differences but helps further refactoring. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: introduce cgroup_control() and cgroup_ss_mask()Tejun Heo
When a controller is enabled and visible on a non-root cgroup is determined by subtree_control and subtree_ss_mask of the parent cgroup. For a root cgroup, by the type of the hierarchy and which controllers are attached to it. Deciding the above on each usage is fragile and unnecessarily complicates the users. This patch introduces cgroup_control() and cgroup_ss_mask() which calculate and return the [visibly] enabled subsyste mask for the specified cgroup and conver the existing usages. * cgroup_e_css() is restructured for simplicity. * cgroup_calc_subtree_ss_mask() and cgroup_subtree_control_write() no longer need to distinguish root and non-root cases. * With cgroup_control(), cgroup_controllers_show() can now handle both root and non-root cases. cgroup_root_controllers_show() is removed. v2: cgroup_control() updated to yield the correct result on v1 hierarchies too. cgroup_subtree_control_write() converted. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: factor out cgroup_create() out of cgroup_mkdir()Tejun Heo
We're in the process of refactoring cgroup and css management paths to separate them out to eventually allow cgroups which aren't visible through cgroup fs. This patch factors out cgroup_create() out of cgroup_mkdir(). cgroup_create() contains all internal object creation and initialization. cgroup_mkdir() uses cgroup_create() to create the internal cgroup and adds interface directory and file creation. This patch doesn't cause any behavior differences. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: reorder operations in cgroup_mkdir()Tejun Heo
Currently, operations to initialize internal objects and create interface directory and files are intermixed in cgroup_mkdir(). We're in the process of refactoring cgroup and css management paths to separate them out to eventually allow cgroups which aren't visible through cgroup fs. This patch reorders operations inside cgroup_mkdir() so that interface directory and file handling comes after internal object initialization. This will enable further refactoring. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: explicitly track whether a cgroup_subsys_state is visible to userlandTejun Heo
Currently, whether a css (cgroup_subsys_state) has its interface files created is not tracked and assumed to change together with the owning cgroup's lifecycle. cgroup directory and interface creation is being separated out from internal object creation to help refactoring and eventually allow cgroups which are not visible through cgroupfs. This patch adds CSS_VISIBLE to track whether a css has its interface files created and perform management operations only when necessary which helps decoupling interface file handling from internal object lifecycle. After this patch, all css interface file management functions can be called regardless of the current state and will achieve the expected result. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: separate out interface file creation from css creationTejun Heo
Currently, interface files are created when a css is created depending on whether @visible is set. This patch separates out the two into separate steps to help code refactoring and eventually allow cgroups which aren't visible through cgroup fs. Move css_populate_dir() out of create_css() and drop @visible. While at it, rename the function to css_create() for consistency. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: suppress spurious de-populated eventsTejun Heo
During task migration, tasks may transfer between two css_sets which are associated with the same cgroup. If those tasks are the only tasks in the cgroup, this currently triggers a spurious de-populated event on the cgroup. Fix it by bumping up populated count before bumping it down during migration to ensure that it doesn't reach zero spuriously. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-03cgroup: re-hash init_css_set after subsystems are initializedTejun Heo
css_sets are hashed by their subsys[] contents and in cgroup_init() init_css_set is hashed early, before subsystem inits, when all entries in its subsys[] are NULL, so that cgroup_dfl_root initialization can find and link to it. As subsystems are initialized, init_css_set.subsys[] is filled up but the hashing is never updated making init_css_set hashed in the wrong place. While incorrect, this doesn't cause a critical failure as css_set management code would create an identical css_set dynamically. Fix it by rehashing init_css_set after subsystems are initialized. While at it, drop unnecessary @key local variable. Signed-off-by: Tejun Heo <tj@kernel.org> Acked-by: Zefan Li <lizefan@huawei.com>
2016-03-01cgroup: reset css on destructionVladimir Davydov
An associated css can be around for quite a while after a cgroup directory has been removed. In general, it makes sense to reset it to defaults so as not to worry about any remnants. For instance, memory cgroup needs to reset memory.low, otherwise pages charged to a dead cgroup might never get reclaimed. There's ->css_reset callback, which would fit perfectly for the purpose. Currently, it's only called when a subsystem is disabled in the unified hierarchy and there are other subsystems dependant on it. Let's call it on css destruction as well. Suggested-by: Johannes Weiner <hannes@cmpxchg.org> Signed-off-by: Vladimir Davydov <vdavydov@virtuozzo.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-02-29cgroup: fix and restructure error handling in copy_cgroup_ns()Tejun Heo
copy_cgroup_ns()'s error handling was broken and the attempt to fix it d22025570e2e ("cgroup: fix alloc_cgroup_ns() error handling in copy_cgroup_ns()") was broken too in that it ended up trying an ERR_PTR() value. There's only one place where copy_cgroup_ns() needs to perform cleanup after failure. Simplify and fix the error handling by removing the goto's. Signed-off-by: Tejun Heo <tj@kernel.org> Reported-by: Dan Carpenter <dan.carpenter@oracle.com> Acked-by: Serge E. Hallyn <serge.hallyn@ubuntu.com>
2016-02-27cgroup: fix a mistake in warning messageXiubo Li
There is a mistake about the print format name:id <--> %d:%s, which the name is 'char *' type and id is 'int' type. Change "name:id" to "id:name" instead to be consistent with "cgroup_subsys %d:%s". Signed-off-by: Xiubo Li <lixiubo@cmss.chinamobile.com> Acked-by: Zefan Li <lizefan@huawei.com> Signed-off-by: Tejun Heo <tj@kernel.org>
2016-02-23cgroup: use ->subtree_control when testing no internal process ruleTejun Heo
No internal process rule is enforced by cgroup_migrate_prepare_dst() during process migration. It tests whether the target cgroup's ->child_subsys_mask is zero which is different from "subtree_control" write path which tests ->subtree_control. This hasn't mattered because up until now, both ->child_subsys_mask and ->subtree_control are zero or non-zero at the same time. However, with the planned addition of implicit controllers, this will no longer be true. This patch prepares for the change by making cgorup_migrate_prepare_dst() test ->subtree_control instead. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-02-23cgroup: make css_tryget_online_from_dir() also recognize cgroup2 fsTejun Heo
The function currently returns -EBADF for a directory on the default hierarchy. Make it also recognize cgroup2_fs_type. This will be used for perf_event cgroup2 support. Signed-off-by: Tejun Heo <tj@kernel.org>
2016-02-23cgroup: s/cgrp_dfl_root_/cgrp_dfl_/Tejun Heo
These var names are unnecessarily unwiedly and another similar variable will be added. Let's shorten them. Signed-off-by: Tejun Heo <tj@kernel.org>