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bfb0b80db5
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Zefan Li bfb0b80db5 cgroup: avoid attaching a cgroup root to two different superblocks 
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 <dvyukov@google.com>
Signed-off-by: Zefan Li <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2017-04-11 09:00:57 +09:00
..
bpf Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2017-03-04 17:31:39 -08:00
cgroup cgroup: avoid attaching a cgroup root to two different superblocks 2017-04-11 09:00:57 +09:00
configs config: android-base: enable hardened usercopy and kernel ASLR 2017-02-27 18:43:46 -08:00
debug sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
events sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq sched/headers: Prepare to move the get_task_struct()/put_task_struct() and related APIs from <linux/sched.h> to <linux/sched/task.h> 2017-03-02 08:42:40 +01:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
power Merge branch 'WIP.sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2017-03-03 10:16:38 -08:00
printk sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
rcu sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
sched sched/headers: Move cputime functionality from <linux/sched.h> and <linux/cputime.h> into <linux/sched/cputime.h> 2017-03-03 01:45:22 +01:00
time sched/headers: Prepare to move exit_files() and exit_itimers() from <linux/sched.h> to <linux/sched/task.h> 2017-03-02 08:42:40 +01:00
trace sched/headers: Prepare to use <linux/rcuupdate.h> instead of <linux/rculist.h> in <linux/sched.h> 2017-03-02 08:42:38 +01:00
.gitignore
acct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
async.c
audit_fsnotify.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit_tree.c Merge branch 'stable-4.10' of git://git.infradead.org/users/pcmoore/audit 2017-01-05 23:06:06 -08:00
audit_watch.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2016-12-17 18:44:00 -08:00
audit.c Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
audit.h Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
auditfilter.c audit: add support for session ID user filter 2016-11-29 15:10:12 -05:00
auditsc.c Merge branch 'stable-4.11' of git://git.infradead.org/users/pcmoore/audit 2017-02-21 13:25:50 -08:00
backtracetest.c
bounds.c
capability.c capability: export has_capability 2017-01-12 07:01:56 -07:00
compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
configs.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
context_tracking.c
cpu_pm.c
cpu.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
crash_dump.c
cred.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h> 2017-03-02 08:42:28 +01:00
delayacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
extable.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2017-02-22 10:15:09 -08:00
fork.c sched/headers, RCU: Move rcu_copy_process() from <linux/sched/task.h> to kernel/fork.c 2017-03-03 01:43:46 +01:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex_compat.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
futex.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/mm.h> 2017-03-02 08:42:28 +01:00
groups.c Replace <asm/uaccess.h> with <linux/uaccess.h> globally 2016-12-24 11:46:01 -08:00
hung_task.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
irq_work.c
jump_label.c This release has no new tracing features, just clean ups, minor fixes 2017-02-27 13:26:17 -08:00
kallsyms.c bpf: make jited programs visible in traces 2017-02-17 13:40:05 -05:00
kcmp.c
Kconfig.freezer
Kconfig.hz
Kconfig.locks locking/mutex: Allow MUTEX_SPIN_ON_OWNER when DEBUG_MUTEXES 2016-10-25 11:31:51 +02:00
Kconfig.preempt
kcov.c kcov: make kcov work properly with KASLR enabled 2016-12-20 09:48:47 -08:00
kexec_core.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/pmladek/printk 2017-02-22 17:33:34 -08:00
kexec_file.c ima: on soft reboot, save the measurement list 2016-12-20 09:48:44 -08:00
kexec_internal.h kexec_file: Allow arch-specific memory walking for kexec_add_buffer 2016-11-30 23:14:57 +11:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kmod.c sched/headers, vfs/execve: Prepare to move the do_execve*() prototypes from <linux/sched.h> to <linux/binfmts.h> 2017-03-02 08:42:39 +01:00
kprobes.c powerpc updates for 4.11 part 1. 2017-02-22 10:30:38 -08:00
ksysfs.c kernel/ksysfs.c: add __ro_after_init to bin_attribute structure 2017-02-24 17:46:56 -08:00
kthread.c cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups 2017-03-17 10:18:47 -04:00
latencytop.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
Makefile cgroup: move cgroup files under kernel/cgroup/ 2016-12-27 14:49:05 -05:00
membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-01-23 11:32:16 -08:00
memremap.c mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done} 2017-02-24 17:46:53 -08:00
module_signing.c
module-internal.h
module.c Modules updates for v4.11 2017-02-22 17:08:33 -08:00
notifier.c kernel/notifier.c: simplify expression 2017-02-24 17:46:56 -08:00
nsproxy.c
padata.c padata: Remove unused but set variables 2016-10-25 11:08:10 +08:00
panic.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
params.c
pid_namespace.c sched/headers: Prepare for the reduction of <linux/sched.h>'s signal API dependency 2017-03-02 08:42:37 +01:00
pid.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
profile.c sched/headers: Prepare to move sched_info_on() and force_schedstat_enabled() from <linux/sched.h> to <linux/sched/stat.h> 2017-03-02 08:42:39 +01:00
ptrace.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
range.c
reboot.c
relay.c lib/vsprintf.c: remove %Z support 2017-02-27 18:43:47 -08:00
resource.c
seccomp.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task_stack.h> 2017-03-02 08:42:36 +01:00
signal.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
smp.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/idle.h> 2017-03-02 08:42:26 +01:00
smpboot.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
smpboot.h
softirq.c softirq: Display IRQ_POLL for irq-poll statistics 2016-10-21 15:45:47 -06:00
stacktrace.c stacktrace, lockdep: Fix address, newline ugliness 2017-02-08 08:21:31 +01:00
stop_machine.c locking/core, stop_machine: Yield the CPU during stop machine() 2016-11-16 10:15:09 +01:00
sys_ni.c move aio compat to fs/aio.c 2016-12-22 22:58:37 -05:00
sys.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
sysctl_binary.c sysctl: add KERN_CONT to deprecated_sysctl_warning() 2016-12-14 16:04:07 -08:00
sysctl.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/coredump.h> 2017-03-02 08:42:28 +01:00
task_work.c task_work: use READ_ONCE/lockless_dereference, avoid pi_lock if !task_works 2016-08-02 19:35:02 -04:00
taskstats.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net 2016-11-15 10:54:36 -05:00
test_kprobes.c
torture.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/clock.h> 2017-03-02 08:42:27 +01:00
tracepoint.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/task.h> 2017-03-02 08:42:35 +01:00
tsacct.c sched/headers: Prepare to move cputime functionality from <linux/sched.h> into <linux/sched/cputime.h> 2017-03-02 08:42:39 +01:00
ucount.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
uid16.c sched/headers: Prepare to remove <linux/cred.h> inclusion from <linux/sched.h> 2017-03-02 08:42:31 +01:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user_namespace.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/signal.h> 2017-03-02 08:42:29 +01:00
user-return-notifier.c
user.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/user.h> 2017-03-02 08:42:29 +01:00
utsname_sysctl.c sched/headers: Remove <linux/rwsem.h> from <linux/sched.h> 2017-03-03 01:45:36 +01:00
utsname.c sched/headers: Prepare to move the task_lock()/unlock() APIs to <linux/sched/task.h> 2017-03-02 08:42:38 +01:00
watchdog_hld.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
watchdog.c sched/headers: Prepare for new header dependencies before moving code to <linux/sched/debug.h> 2017-03-02 08:42:34 +01:00
workqueue_internal.h
workqueue.c time: Remove CONFIG_TIMER_STATS 2017-02-10 11:15:08 +01:00