linux/kernel
Anjana V Kumar 5be794dc4b cgroup: fix to break the while loop in cgroup_attach_task() correctly
commit ea84753c98 upstream.

Both Anjana and Eunki reported a stall in the while_each_thread loop
in cgroup_attach_task().

It's because, when we attach a single thread to a cgroup, if the cgroup
is exiting or is already in that cgroup, we won't break the loop.

If the task is already in the cgroup, the bug can lead to another thread
being attached to the cgroup unexpectedly:

  # echo 5207 > tasks
  # cat tasks
  5207
  # echo 5207 > tasks
  # cat tasks
  5207
  5215

What's worse, if the task to be attached isn't the leader of the thread
group, we might never exit the loop, hence cpu stall. Thanks for Oleg's
analysis.

This bug was introduced by commit 081aa458c3
("cgroup: consolidate cgroup_attach_task() and cgroup_attach_proc()")

[ lizf: - fixed the first continue, pointed out by Oleg,
        - rewrote changelog. ]

Reported-by: Eunki Kim <eunki_kim@samsung.com>
Reported-by: Anjana V Kumar <anjanavk12@gmail.com>
Signed-off-by: Anjana V Kumar <anjanavk12@gmail.com>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2013-11-13 12:05:30 +09:00
..
cpu idle: Enable interrupts in the weak arch_cpu_idle() implementation 2013-06-14 23:01:05 +02:00
debug kgdb/sysrq: fix inconstistent help message of sysrq key 2013-04-30 17:04:10 -07:00
events uprobes: Fix utask->depth accounting in handle_trampoline() 2013-09-26 17:18:27 -07:00
gcov kernel/gcov: remove depends on CONFIG_EXPERIMENTAL 2013-01-11 11:39:33 -08:00
irq genirq: Fix can_request_irq() for IRQs without an action 2013-07-21 18:21:27 -07:00
power PM / QoS: Fix workqueue deadlock when using pm_qos_update_request_timeout() 2013-08-20 08:43:05 -07:00
sched sched/fair: Fix small race where child->se.parent,cfs_rq might point to invalid ones 2013-10-01 09:17:45 -07:00
time timekeeping: Fix HRTICK related deadlock from ntp lock changes 2013-10-01 09:17:45 -07:00
trace ftrace: Check module functions being traced on reload 2013-08-29 09:47:34 -07:00
.gitignore kernel/hz.bc: ignore. 2013-04-22 07:09:06 -07:00
acct.c fs: Fix hang with BSD accounting on frozen filesystem 2013-05-04 14:57:58 -04:00
async.c async: rename and redefine async_func_ptr 2013-03-12 13:59:14 -07:00
audit_tree.c kernel/audit_tree.c:audit_add_tree_rule(): protect `rule' from kill_rules() 2013-06-12 16:29:46 -07:00
audit_watch.c audit: catch possible NULL audit buffers 2013-01-11 14:54:55 -08:00
audit.c audit: fix endless wait in audit_log_start() 2013-10-01 09:17:48 -07:00
audit.h Merge git://git.infradead.org/users/eparis/audit 2013-05-11 14:29:11 -07:00
auditfilter.c auditfilter.c: fix kernel-doc warnings 2013-05-24 16:22:52 -07:00
auditsc.c audit: Make testing for a valid loginuid explicit. 2013-05-07 22:27:15 -04:00
backtracetest.c
bounds.c
capability.c Add file_ns_capable() helper function for open-time capability checking 2013-04-14 10:06:31 -07:00
cgroup_freezer.c cgroup: rename ->create/post_create/pre_destroy/destroy() to ->css_alloc/online/offline/free() 2012-11-19 08:13:38 -08:00
cgroup.c cgroup: fix to break the while loop in cgroup_attach_task() correctly 2013-11-13 12:05:30 +09:00
compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-05-01 07:21:43 -07:00
configs.c proc: Supply PDE attribute setting accessor functions 2013-05-01 17:29:18 -04:00
context_tracking.c Merge branch 'sched-urgent-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2013-06-20 08:18:35 -10:00
cpu_pm.c
cpu.c CPU hotplug: provide a generic helper to disable/enable CPU hotplug 2013-06-12 16:29:44 -07:00
cpuset.c cpuset: fix the return value of cpuset_write_u64() 2013-08-20 08:43:05 -07:00
crash_dump.c
cred.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/ebiederm/user-namespace 2012-12-18 10:55:28 -08:00
delayacct.c cputime: Use accessors to read task cputime stats 2013-01-27 19:23:31 +01:00
dma.c
elfcore.c
exec_domain.c
exit.c move exit_task_namespaces() outside of exit_notify() 2013-06-15 05:39:08 +04:00
extable.c extable: Flip the sorting message 2013-04-15 13:25:16 +02:00
fork.c pidns: fix vfork() after unshare(CLONE_NEWPID) 2013-09-26 17:18:28 -07:00
freezer.c
futex_compat.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/signal 2013-02-23 18:50:11 -08:00
futex.c futex: Take hugepages into account when generating futex_key 2013-07-13 11:42:26 -07:00
groups.c
hrtimer.c hrtimers: Move SMP function call to thread context 2013-07-28 16:30:22 -07:00
hung_task.c
irq_work.c Merge branch 'nohz/printk-v8' into irq/core 2013-02-05 00:48:46 +01:00
itimer.c
jump_label.c
kallsyms.c kernel: kallsyms: memory override issue, need check destination buffer length 2013-04-15 15:17:26 +09:30
kcmp.c kcmp: include linux/ptrace.h 2012-12-20 17:40:19 -08:00
Kconfig.freezer
Kconfig.hz
Kconfig.locks
Kconfig.preempt
kexec.c kexec: Use min() and min_t() to simplify logic 2013-04-30 17:04:07 -07:00
kmod.c usermodehelper: check subprocess_info->path != NULL 2013-05-16 12:01:11 -07:00
kprobes.c kprobes: Fix to free gone and unused optprobes 2013-05-28 10:37:59 +02:00
ksysfs.c Merge branch 'core-rcu-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2012-12-11 18:10:49 -08:00
kthread.c kthread: implement probe_kthread_data() 2013-04-30 17:04:02 -07:00
latencytop.c
lglock.c
lockdep_internals.h
lockdep_proc.c
lockdep_states.h
lockdep.c Merge branch 'for-3.10/drivers' of git://git.kernel.dk/linux-block 2013-05-08 11:51:05 -07:00
Makefile We get rid of the general module prefix confusion with a binary config option, 2013-05-05 10:58:06 -07:00
modsign_certificate.S CONFIG_SYMBOL_PREFIX: cleanup. 2013-03-15 15:09:43 +10:30
modsign_pubkey.c keys: use keyring_alloc() to create module signing keyring 2012-12-20 17:40:21 -08:00
module_signing.c MODSIGN: Don't use enum-type bitfields in module signature info block 2012-12-05 11:27:24 +10:30
module-internal.h
module.c module: do percpu allocation after uniqueness check. No, really! 2013-07-13 11:42:26 -07:00
mutex-debug.c
mutex-debug.h
mutex.c mutex: Back out architecture specific check for negative mutex count 2013-04-19 09:33:36 +02:00
mutex.h
notifier.c
nsproxy.c proc: Split the namespace stuff out into linux/proc_ns.h 2013-05-01 17:29:39 -04:00
padata.c padata: use __this_cpu_read per-cpu helper 2012-12-06 17:16:23 +08:00
panic.c dump_stack: implement arch-specific hardware description in task dumps 2013-04-30 17:04:02 -07:00
params.c params: Fix potential memory leak in add_sysfs_param() 2013-03-18 11:40:21 +00:00
pid_namespace.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
pid.c pidns: Fix hang in zap_pid_ns_processes by sending a potentially extra wakeup 2013-09-26 17:18:27 -07:00
posix-cpu-timers.c posix_timers: Fix pre-condition to stop the tick on full dynticks 2013-04-22 19:59:25 +02:00
posix-timers.c posix-timers: Remove unused variable 2013-04-18 12:51:19 +02:00
printk.c printk: Fix rq->lock vs logbuf_lock unlock lock inversion 2013-07-25 14:07:31 -07:00
profile.c proc: Supply PDE attribute setting accessor functions 2013-05-01 17:29:18 -04:00
ptrace.c Fix: kernel/ptrace.c: ptrace_peek_siginfo() missing __put_user() validation 2013-06-29 11:29:08 -07:00
range.c range: Do not add new blank slot with add_range_with_merge 2013-06-18 11:32:10 -05:00
rcu.h rcu: Provide RCU CPU stall warnings for tiny RCU 2013-01-28 22:06:21 -08:00
rcupdate.c Merge branches 'doctorture.2013.01.29a', 'fixes.2013.01.26a', 'tagcb.2013.01.24a' and 'tiny.2013.01.29b' into HEAD 2013-01-28 22:25:21 -08:00
rcutiny_plugin.h rcu: Provide RCU CPU stall warnings for tiny RCU 2013-01-28 22:06:21 -08:00
rcutiny.c Merge branches 'doctorture.2013.01.29a', 'fixes.2013.01.26a', 'tagcb.2013.01.24a' and 'tiny.2013.01.29b' into HEAD 2013-01-28 22:25:21 -08:00
rcutorture.c rcu: Allow rcutorture to be built at low optimization levels 2013-02-04 12:18:20 -08:00
rcutree_plugin.h rcu: Don't allocate bootmem from rcu_init() 2013-05-15 10:41:12 -07:00
rcutree_trace.c rcutrace: single_open() leaks 2013-05-05 00:16:35 -04:00
rcutree.c rcu: Fix deadlock with CPU hotplug, RCU GP init, and timer migration 2013-06-10 13:37:12 -07:00
rcutree.h rcu: Don't call wakeup() with rcu_node structure ->lock held 2013-06-10 13:37:11 -07:00
relay.c Merge branch 'for-3.10/core' of git://git.kernel.dk/linux-block 2013-05-08 10:13:35 -07:00
res_counter.c res_counter: return amount of charges after res_counter_uncharge() 2012-12-18 15:02:12 -08:00
resource.c mem hotunplug: fix kfree() of bootmem memory 2013-04-29 15:54:40 -07:00
rtmutex_common.h
rtmutex-debug.c sched/rt: Move rt specific bits into new header file 2013-02-07 20:51:08 +01:00
rtmutex-debug.h
rtmutex-tester.c locking/rtmutex/tester: Set correct permissions on sysfs files 2013-04-10 14:48:37 +02:00
rtmutex.c sched/rt: Move rt specific bits into new header file 2013-02-07 20:51:08 +01:00
rtmutex.h
rwsem.c Revert "rw_semaphore: remove up/down_read_non_owner" 2013-03-23 15:53:52 -07:00
seccomp.c seccomp: allow BPF_XOR based ALU instructions. 2013-03-26 11:07:19 +11:00
semaphore.c semaphore: use `bool' type for semaphore_waiter's up 2013-04-30 17:04:08 -07:00
signal.c Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2013-05-01 14:08:52 -07:00
smp.c kernel/smp.c: cleanups 2013-04-30 17:04:03 -07:00
smpboot.c kthread: Prevent unpark race which puts threads on the wrong cpu 2013-04-12 14:18:43 +02:00
smpboot.h
softirq.c irq: Force hardirq exit's softirq processing on its own stack 2013-10-13 16:08:34 -07:00
spinlock.c
srcu.c srcu: use ACCESS_ONCE() to access sp->completed in srcu_read_lock() 2013-02-07 15:19:36 -08:00
stacktrace.c
stop_machine.c stop_machine: Mark per cpu stopper enabled early 2013-02-26 22:25:17 +01:00
sys_ni.c unify compat fanotify_mark(2), switch to COMPAT_SYSCALL_DEFINE 2013-05-09 13:46:38 -04:00
sys.c reboot: rigrate shutdown/reboot to boot cpu 2013-06-12 16:29:44 -07:00
sysctl_binary.c switch compat_sys_sysctl to COMPAT_SYSCALL_DEFINE 2013-05-09 14:53:20 -04:00
sysctl.c mm: replace hardcoded 3% with admin_reserve_pages knob 2013-04-29 15:54:36 -07:00
task_work.c
taskstats.c
test_kprobes.c kernel/: rename random32() to prandom_u32() 2013-04-29 18:28:42 -07:00
time.c timekeeping: Use inject_offset in warp_clock 2013-03-15 16:50:20 -07:00
timeconst.bc kernel: Replace timeconst.pl with a bc script 2013-02-16 23:17:25 +01:00
timer.c timer: Fix jiffies wrap behavior of round_jiffies_common() 2013-07-21 18:21:31 -07:00
tracepoint.c Tracing updates for Linux 3.10 2013-04-29 13:55:38 -07:00
tsacct.c cputime: Use accessors to read task cputime stats 2013-01-27 19:23:31 +01:00
uid16.c make SYSCALL_DEFINE<n>-generated wrappers do asmlinkage_protect 2013-03-03 22:58:33 -05:00
up.c
user_namespace.c userns: limit the maximum depth of user_namespace->parent chain 2013-08-11 18:35:25 -07:00
user-return-notifier.c hlist: drop the node parameter from iterators 2013-02-27 19:10:24 -08:00
user.c Merge branch 'for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/viro/vfs 2013-05-01 17:51:54 -07:00
utsname_sysctl.c kernel/utsname_sysctl.c: put get/get_uts() into CONFIG_PROC_SYSCTL code block 2013-02-27 19:10:22 -08:00
utsname.c proc: Split the namespace stuff out into linux/proc_ns.h 2013-05-01 17:29:39 -04:00
wait.c propagate name change to comments in kernel source 2012-12-06 10:39:54 +01:00
watchdog.c watchdog: Add comments to explain the watchdog_disabled variable 2013-03-14 08:24:05 +01:00
workqueue_internal.h workqueue: include workqueue info when printing debug dump of a worker task 2013-04-30 17:04:02 -07:00
workqueue.c workqueue: cond_resched() after processing each work item 2013-09-07 22:09:58 -07:00