linux-toradex.git/kernel/cgroup, branch v4.12-rc4

Merge branch 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2017-05-01T20:52:24+00:00

Pull cgroup updates from Tejun Heo:
 "Nothing major. Two notable fixes are Li's second stab at fixing the
  long-standing race condition in the mount path and suppression of
  spurious warning from cgroup_get(). All other changes are trivial"

* 'for-4.12' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: mark cgroup_get() with __maybe_unused
  cgroup: avoid attaching a cgroup root to two different superblocks, take 2
  cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc()
  cgroup: move cgroup_subsys_state parent field for cache locality
  cpuset: Remove cpuset_update_active_cpus()'s parameter.
  cgroup: switch to BUG_ON()
  cgroup: drop duplicate header nsproxy.h
  kernel: convert css_set.refcount from atomic_t to refcount_t
  kernel: convert cgroup_namespace.count from atomic_t to refcount_t

cgroup: mark cgroup_get() with __maybe_unused

2017-05-01T19:24:14+00:00

a590b90d472f ("cgroup: fix spurious warnings on cgroup_is_dead() from
cgroup_sk_alloc()") converted most cgroup_get() usages to
cgroup_get_live() leaving cgroup_sk_alloc() the sole user of
cgroup_get().  When !CONFIG_SOCK_CGROUP_DATA, this ends up triggering
unused warning for cgroup_get().

Silence the warning by adding __maybe_unused to cgroup_get().

Reported-by: Stephen Rothwell 
Link: http://lkml.kernel.org/r/20170501145340.17e8ef86@canb.auug.org.au
Signed-off-by: Tejun Heo

cgroup: avoid attaching a cgroup root to two different superblocks, take 2

2017-04-28T22:04:54+00:00

Commit bfb0b80db5f9 ("cgroup: avoid attaching a cgroup root to two
different superblocks") is broken.  Now we try to fix the race by
delaying the initialization of cgroup root refcnt until a superblock
has been allocated.

Reported-by: Dmitry Vyukov 
Reported-by: Andrei Vagin 
Tested-by: Andrei Vagin 
Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo

cgroup: fix spurious warnings on cgroup_is_dead() from cgroup_sk_alloc()

2017-04-28T19:28:20+00:00

cgroup_get() expected to be called only on live cgroups and triggers
warning on a dead cgroup; however, cgroup_sk_alloc() may be called
while cloning a socket which is left in an empty and removed cgroup
and thus may legitimately duplicate its reference on a dead cgroup.
This currently triggers the following warning spuriously.

 WARNING: CPU: 14 PID: 0 at kernel/cgroup.c:490 cgroup_get+0x55/0x60
 ...
  [] __warn+0xd3/0xf0
  [] warn_slowpath_null+0x1e/0x20
  [] cgroup_get+0x55/0x60
  [] cgroup_sk_alloc+0x51/0xe0
  [] sk_clone_lock+0x2db/0x390
  [] inet_csk_clone_lock+0x16/0xc0
  [] tcp_create_openreq_child+0x23/0x4b0
  [] tcp_v6_syn_recv_sock+0x91/0x670
  [] tcp_check_req+0x3a6/0x4e0
  [] tcp_v6_rcv+0x693/0xa00
  [] ip6_input_finish+0x59/0x3e0
  [] ip6_input+0x32/0xb0
  [] ip6_rcv_finish+0x57/0xa0
  [] ipv6_rcv+0x318/0x4d0
  [] __netif_receive_skb_core+0x2d7/0x9a0
  [] __netif_receive_skb+0x16/0x70
  [] netif_receive_skb_internal+0x23/0x80
  [] napi_gro_frags+0x208/0x270
  [] mlx4_en_process_rx_cq+0x74c/0xf40
  [] mlx4_en_poll_rx_cq+0x30/0x90
  [] net_rx_action+0x210/0x350
  [] __do_softirq+0x106/0x2c7
  [] irq_exit+0x9d/0xa0 [] do_IRQ+0x54/0xd0
  [] common_interrupt+0x7f/0x7f 
  [] cpuidle_enter+0x17/0x20
  [] cpu_startup_entry+0x2a9/0x2f0
  [] start_secondary+0xf1/0x100

This patch renames the existing cgroup_get() with the dead cgroup
warning to cgroup_get_live() after cgroup_kn_lock_live() and
introduces the new cgroup_get() which doesn't check whether the cgroup
is live or dead.

All existing cgroup_get() users except for cgroup_sk_alloc() are
converted to use cgroup_get_live().

Fixes: d979a39d7242 ("cgroup: duplicate cgroup reference when cloning sockets")
Cc: stable@vger.kernel.org # v4.5+
Cc: Johannes Weiner 
Reported-by: Chris Mason 
Signed-off-by: Tejun Heo

Merge branch 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2017-04-16T18:48:10+00:00

Pull cgroup fix from Tejun Heo:
 "Unfortunately, the commit to fix the cgroup mount race in the previous
  pull request can lead to hangs.

  The original bug has been around for a while and isn't too likely to
  be triggered in usual use cases. Revert the commit for now"

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  Revert "cgroup: avoid attaching a cgroup root to two different superblocks"

Revert "cgroup: avoid attaching a cgroup root to two different superblocks"

2017-04-16T14:17:37+00:00

This reverts commit bfb0b80db5f9dca5ac0a5fd0edb765ee555e5a8e.

Andrei reports CRIU test hangs with the patch applied.  The bug fixed
by the patch isn't too likely to trigger in actual uses.  Revert the
patch for now.

Signed-off-by: Tejun Heo 
Reported-by: Andrei Vagin 
Link: http://lkml.kernel.org/r/20170414232737.GC20350@outlook.office365.com

Merge branch 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

2017-04-12T06:38:16+00:00

Pull cgroup fixes from Tejun Heo:
 "This contains fixes for two long standing subtle bugs:

   - kthread_bind() on a new kthread binds it to specific CPUs and
     prevents userland from messing with the affinity or cgroup
     membership. Unfortunately, for cgroup membership, there's a window
     between kthread creation and kthread_bind*() invocation where the
     kthread can be moved into a non-root cgroup by userland.

     Depending on what controllers are in effect, this can assign the
     kthread unexpected attributes. For example, in the reported case,
     workqueue workers ended up in a non-root cpuset cgroups and had
     their CPU affinities overridden. This broke workqueue invariants
     and led to workqueue stalls.

     Fixed by closing the window between kthread creation and
     kthread_bind() as suggested by Oleg.

   - There was a bug in cgroup mount path which could allow two
     competing mount attempts to attach the same cgroup_root to two
     different superblocks.

     This was caused by mishandling return value from kernfs_pin_sb().

     Fixed"

* 'for-4.11-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup: avoid attaching a cgroup root to two different superblocks
  cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups

cgroup: avoid attaching a cgroup root to two different superblocks

2017-04-11T00:00:57+00:00

Run this:

    touch file0
    for ((; ;))
    {
        mount -t cpuset xxx file0
    }

And this concurrently:

    touch file1
    for ((; ;))
    {
        mount -t cpuset xxx file1
    }

We'll trigger a warning like this:

 ------------[ cut here ]------------
 WARNING: CPU: 1 PID: 4675 at lib/percpu-refcount.c:317 percpu_ref_kill_and_confirm+0x92/0xb0
 percpu_ref_kill_and_confirm called more than once on css_release!
 CPU: 1 PID: 4675 Comm: mount Not tainted 4.11.0-rc5+ #5
 Hardware name: Bochs Bochs, BIOS Bochs 01/01/2007
 Call Trace:
  dump_stack+0x63/0x84
  __warn+0xd1/0xf0
  warn_slowpath_fmt+0x5f/0x80
  percpu_ref_kill_and_confirm+0x92/0xb0
  cgroup_kill_sb+0x95/0xb0
  deactivate_locked_super+0x43/0x70
  deactivate_super+0x46/0x60
 ...
 ---[ end trace a79f61c2a2633700 ]---

Here's a race:

  Thread A				Thread B

  cgroup1_mount()
    # alloc a new cgroup root
    cgroup_setup_root()
					cgroup1_mount()
					  # no sb yet, returns NULL
					  kernfs_pin_sb()

					  # but succeeds in getting the refcnt,
					  # so re-use cgroup root
					  percpu_ref_tryget_live()
    # alloc sb with cgroup root
    cgroup_do_mount()

  cgroup_kill_sb()
					  # alloc another sb with same root
					  cgroup_do_mount()

					cgroup_kill_sb()

We end up using the same cgroup root for two different superblocks,
so percpu_ref_kill() will be called twice on the same root when the
two superblocks are destroyed.

We should fix to make sure the superblock pinning is really successful.

Cc: stable@vger.kernel.org # 3.16+
Reported-by: Dmitry Vyukov 
Signed-off-by: Zefan Li 
Signed-off-by: Tejun Heo

cpuset: Remove cpuset_update_active_cpus()'s parameter.

2017-04-10T23:57:54+00:00

In cpuset_update_active_cpus(), cpu_online isn't used anymore. Remove
it.

Signed-off-by: Rakib Mullick
Acked-by: Zefan Li 
Signed-off-by: Tejun Heo

cgroup: switch to BUG_ON()

2017-03-27T17:59:12+00:00

Use BUG_ON() rather than an explicit if followed by BUG() for
improved readability and also consistency.

Signed-off-by: Nicholas Mc Guire 
Signed-off-by: Tejun Heo