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Konstantin Khlebnikov 62b5776c8c sched/cgroup: Move sched_online_group() back into css_online() to fix crash 
commit 96b777452d upstream.

Commit:

  2f5177f0fd ("sched/cgroup: Fix/cleanup cgroup teardown/init")

.. moved sched_online_group() from css_online() to css_alloc().
It exposes half-baked task group into global lists before initializing
generic cgroup stuff.

LTP testcase (third in cgroup_regression_test) written for testing
similar race in kernels 2.6.26-2.6.28 easily triggers this oops:

  BUG: unable to handle kernel NULL pointer dereference at 0000000000000008
  IP: kernfs_path_from_node_locked+0x260/0x320
  CPU: 1 PID: 30346 Comm: cat Not tainted 4.10.0-rc5-test #4
  Call Trace:
  ? kernfs_path_from_node+0x4f/0x60
  kernfs_path_from_node+0x3e/0x60
  print_rt_rq+0x44/0x2b0
  print_rt_stats+0x7a/0xd0
  print_cpu+0x2fc/0xe80
  ? __might_sleep+0x4a/0x80
  sched_debug_show+0x17/0x30
  seq_read+0xf2/0x3b0
  proc_reg_read+0x42/0x70
  __vfs_read+0x28/0x130
  ? security_file_permission+0x9b/0xc0
  ? rw_verify_area+0x4e/0xb0
  vfs_read+0xa5/0x170
  SyS_read+0x46/0xa0
  entry_SYSCALL_64_fastpath+0x1e/0xad

Here the task group is already linked into the global RCU-protected 'task_groups'
list, but the css->cgroup pointer is still NULL.

This patch reverts this chunk and moves online back to css_online().

Signed-off-by: Konstantin Khlebnikov <khlebnikov@yandex-team.ru>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Fixes: 2f5177f0fd ("sched/cgroup: Fix/cleanup cgroup teardown/init")
Link: http://lkml.kernel.org/r/148655324740.424917.5302984537258726349.stgit@buzz
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Signed-off-by: Matt Fleming <matt@codeblueprint.co.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
 		2017-08-06 18:59:42 -07:00
..
bpf bpf: prevent leaking pointer via xadd on unpriviledged 2017-07-21 07:42:18 +02:00
configs config: android: enable CONFIG_SECCOMP 2016-10-11 15:06:32 -07:00
debug kernel/debug/debug_core.c: more properly delay for secondary CPUs 2017-01-06 10:40:17 +01:00
events Revert "perf/core: Drop kernel samples even though :u is specified" 2017-07-27 15:08:06 -07:00
gcov gcov: add support for gcc version >= 6 2016-07-15 14:54:27 +09:00
irq genirq: Release resources in __setup_irq() error path 2017-06-24 07:11:17 +02:00
livepatch livepatch/module: make TAINT_LIVEPATCH module-specific 2016-08-26 14:42:08 +02:00
locking locking/rwsem-spinlock: Fix EINTR branch in __down_write_common() 2017-07-15 12:16:15 +02:00
power PM / sleep: fix device reference leak in test_suspend 2016-11-02 05:10:04 +01:00
printk printk: use rcuidle console tracepoint 2017-02-23 17:44:36 +01:00
rcu rcu: Add memory barriers for NOCB leader wakeup 2017-07-21 07:42:22 +02:00
sched sched/cgroup: Move sched_online_group() back into css_online() to fix crash 2017-08-06 18:59:42 -07:00
time alarmtimer: don't rate limit one-shot timers 2017-07-27 15:08:08 -07:00
trace tracing: Fix kmemleak in instance_rmdir 2017-07-27 15:08:08 -07:00
.gitignore
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Kconfig.freezer
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Kconfig.hz
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Kconfig.locks
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Kconfig.preempt
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Makefile kernel/watchdog.c: move hardlockup detector to separate file 2017-06-17 06:41:57 +02:00
acct.c
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async.c
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audit.c Merge branch 'stable-4.9' of git://git.infradead.org/users/pcmoore/audit 2016-10-04 14:21:41 -07:00
audit.h Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-07-29 17:54:17 -07:00
audit_fsnotify.c
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audit_tree.c
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audit_watch.c Merge branch 'stable-4.8' of git://git.infradead.org/users/pcmoore/audit 2016-09-01 15:55:56 -07:00
auditfilter.c audit: add fields to exclude filter by reusing user filter 2016-06-27 11:01:00 -04:00
auditsc.c Merge branch 'stable-4.9' of git://git.infradead.org/users/pcmoore/audit 2016-10-04 14:21:41 -07:00
backtracetest.c
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bounds.c
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capability.c ptrace: Capture the ptracer's creds not PT_PTRACE_CAP 2017-01-06 10:40:13 +01:00
cgroup.c cgroup: Prevent kill_css() from being called more than once 2017-06-14 15:06:00 +02:00
cgroup_freezer.c
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cgroup_pids.c cgroup/pids: remove spurious suspicious RCU usage warning 2017-03-26 13:05:58 +02:00
compat.c
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configs.c
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context_tracking.c
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cpu.c smp/hotplug: Replace BUG_ON and react useful 2017-08-06 18:59:41 -07:00
cpu_pm.c
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cpuset.c cpuset: consider dying css as offline 2017-06-14 15:06:00 +02:00
crash_dump.c
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cred.c cred: Reject inodes with invalid ids in set_create_file_as() 2016-06-30 18:05:09 -05:00
delayacct.c
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dma.c
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elfcore.c
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exec_domain.c
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exit.c sched/autogroup: Do not use autogroup->tg in zombie threads 2016-11-22 12:33:43 +01:00
extable.c kernel/extable.c: mark core_kernel_text notrace 2017-07-21 07:42:21 +02:00
fork.c stackprotector: Increase the per-task stack canary's random range from 32 bits to 64 bits on 64-bit platforms 2017-05-25 15:44:46 +02:00
freezer.c freezer, oom: check TIF_MEMDIE on the correct task 2016-07-28 16:07:41 -07:00
futex.c futex: Add missing error handling to FUTEX_REQUEUE_PI 2017-03-22 12:43:40 +01:00
futex_compat.c
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groups.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
hung_task.c hung_task: allow hung_task_panic when hung_task_warnings is 0 2016-10-11 15:06:33 -07:00
irq_work.c
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jump_label.c jump_labels: API for flushing deferred jump label updates 2017-01-19 20:17:59 +01:00
kallsyms.c
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kcmp.c
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kcov.c kcov: add missing #include <linux/sched.h> 2016-12-07 17:10:00 -08:00
kexec.c kexec: allow architectures to override boot mapping 2016-08-02 19:35:27 -04:00
kexec_core.c kexec: add restriction on kexec_load() segment sizes 2016-08-02 19:35:31 -04:00
kexec_file.c kexec: fix double-free when failing to relocate the purgatory 2016-09-01 17:52:01 -07:00
kexec_internal.h
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kmod.c
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kprobes.c tracing/kprobes: Enforce kprobes teardown after testing 2017-05-25 15:44:47 +02:00
ksysfs.c kexec: add a kexec_crash_loaded() function 2016-08-02 19:35:30 -04:00
kthread.c cgroup, kthread: close race window where new kthreads can be migrated to non-root cgroups 2017-04-21 09:31:18 +02:00
latencytop.c
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membarrier.c Fix: Disable sys_membarrier when nohz_full is enabled 2017-03-12 06:41:45 +01:00
memremap.c mm, devm_memremap_pages: hold device_hotplug lock over mem_hotplug_{begin, done} 2017-03-12 06:41:43 +01:00
module-internal.h
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module.c Re-enable CONFIG_MODVERSIONS in a slightly weaker form 2016-11-29 16:01:30 -08:00
module_signing.c
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notifier.c
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nsproxy.c
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padata.c padata: free correct variable 2017-05-20 14:28:40 +02:00
panic.c kernel/panic.c: add missing \n 2017-07-05 14:40:24 +02:00
params.c
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pid.c remove lots of IS_ERR_VALUE abuses 2016-05-27 15:26:11 -07:00
pid_namespace.c pid_ns: Sleep in TASK_INTERRUPTIBLE in zap_pid_ns_processes 2017-05-25 15:44:38 +02:00
profile.c profile: Convert to hotplug state machine 2016-07-15 10:41:42 +02:00
ptrace.c ptrace: Properly initialize ptracer_cred on fork 2017-06-14 15:05:54 +02:00
range.c
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reboot.c
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relay.c relay: check array offset before using it 2017-01-12 11:39:30 +01:00
resource.c
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seccomp.c seccomp: Fix tracer exit notifications during fatal signals 2016-08-30 16:12:46 -07:00
signal.c signal: Only reschedule timers on signals timers have sent 2017-06-29 13:00:29 +02:00
smp.c smp: Allocate smp_call_on_cpu() workqueue on stack too 2016-09-22 14:49:10 +02:00
smpboot.c kthread/smpboot: do not park in kthread_create_on_cpu() 2016-10-11 15:06:33 -07:00
smpboot.h
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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 2017-02-14 15:25:42 -08:00
stop_machine.c Merge branch 'sched-core-for-linus' of git://git.kernel.org/pub/scm/linux/kernel/git/tip/tip 2016-10-03 13:39:00 -07:00
sys.c prctl: make PR_SET_THP_DISABLE wait for mmap_sem killable 2016-05-23 17:04:14 -07:00
sys_ni.c x86/pkeys: Fix pkeys build breakage for some non-x86 arches 2016-09-13 14:41:36 +02:00
sysctl.c sysctl: report EINVAL if value is larger than UINT_MAX for proc_douintvec 2017-07-12 15:01:04 +02:00
sysctl_binary.c kernel/sysctl_binary.c: use generic UUID library 2016-05-20 17:58:30 -07:00
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 taskstats: fix the length of cgroupstats_cmd_get_policy 2016-11-03 16:55:58 -04:00
test_kprobes.c
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torture.c torture: Convert torture_shutdown() to hrtimer 2016-08-22 10:01:49 -07:00
tracepoint.c
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tsacct.c
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ucount.c kernel/ucount.c: mark user_header with kmemleak_ignore() 2017-06-17 06:41:51 +02:00
uid16.c cred: simpler, 1D supplementary groups 2016-10-07 18:46:30 -07:00
up.c smp: Add function to execute a function synchronously on a CPU 2016-09-05 13:52:39 +02:00
user-return-notifier.c
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user.c
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user_namespace.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname.c Merge branch 'nsfs-ioctls' into HEAD 2016-09-22 20:00:36 -05:00
utsname_sysctl.c
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watchdog.c kernel/watchdog: prevent false hardlockup on overloaded system 2017-06-17 06:41:57 +02:00
watchdog_hld.c kernel/watchdog: prevent false hardlockup on overloaded system 2017-06-17 06:41:57 +02:00
workqueue.c kthread: rename probe_kthread_data() to kthread_probe_data() 2016-10-11 15:06:33 -07:00
workqueue_internal.h
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