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linux/kernel/sched
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Mike Galbraith 3d81da8645 Revert "sched, autogroup: Stop going ahead if autogroup is disabled" 
commit fd8ef11730 upstream.

This reverts commit 800d4d30c8.

Between commits 8323f26ce3 ("sched: Fix race in task_group()") and
800d4d30c8 ("sched, autogroup: Stop going ahead if autogroup is
disabled"), autogroup is a wreck.

With both applied, all you have to do to crash a box is disable
autogroup during boot up, then reboot..  boom, NULL pointer dereference
due to commit 800d4d30c8 not allowing autogroup to move things, and
commit 8323f26ce3 making that the only way to switch runqueues:

  BUG: unable to handle kernel NULL pointer dereference at           (null)
  IP: [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
  Pid: 7047, comm: systemd-user-se Not tainted 3.6.8-smp #7 MEDIONPC MS-7502/MS-7502
  RIP: effective_load.isra.43+0x50/0x90
  Process systemd-user-se (pid: 7047, threadinfo ffff880221dde000, task ffff88022618b3a0)
  Call Trace:
    select_task_rq_fair+0x255/0x780
    try_to_wake_up+0x156/0x2c0
    wake_up_state+0xb/0x10
    signal_wake_up+0x28/0x40
    complete_signal+0x1d6/0x250
    __send_signal+0x170/0x310
    send_signal+0x40/0x80
    do_send_sig_info+0x47/0x90
    group_send_sig_info+0x4a/0x70
    kill_pid_info+0x3a/0x60
    sys_kill+0x97/0x1a0
    ? vfs_read+0x120/0x160
    ? sys_read+0x45/0x90
    system_call_fastpath+0x16/0x1b
  Code: 49 0f af 41 50 31 d2 49 f7 f0 48 83 f8 01 48 0f 46 c6 48 2b 07 48 8b bf 40 01 00 00 48 85 ff 74 3a 45 31 c0 48 8b 8f 50 01 00 00 <48> 8b 11 4c 8b 89 80 00 00 00 49 89 d2 48 01 d0 45 8b 59 58 4c
  RIP  [<ffffffff81063ac0>] effective_load.isra.43+0x50/0x90
   RSP <ffff880221ddfbd8>
  CR2: 0000000000000000

Signed-off-by: Mike Galbraith <efault@gmx.de>
Acked-by: Ingo Molnar <mingo@kernel.org>
Cc: Yong Zhang <yong.zhang0@gmail.com>
Cc: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
2012-12-10 10:59:40 -08:00
..
auto_group.c Revert "sched, autogroup: Stop going ahead if autogroup is disabled" 2012-12-10 10:59:40 -08:00
auto_group.h Revert "sched, autogroup: Stop going ahead if autogroup is disabled" 2012-12-10 10:59:40 -08:00
clock.c
core.c CPU hotplug, cpusets, suspend: Don't modify cpusets during suspend/resume 2012-10-13 05:38:57 +09:00
cpupri.c kernel-doc: fix kernel-doc warnings in sched 2012-01-23 08:44:54 -08:00
cpupri.h
debug.c sched: Remove sched_switch 2012-01-27 13:28:53 +01:00
fair.c sched: Fix more load-balancing fallout 2012-04-26 12:54:52 +02:00
features.h sched: Fix more load-balancing fallout 2012-04-26 12:54:52 +02:00
idle_task.c sched/nohz: Rewrite and fix load-avg computation -- again 2012-07-19 08:58:56 -07:00
Makefile
rt.c sched/rt: Improve pick_next_highest_task_rt() 2012-03-27 14:52:12 +02:00
sched.h sched: Fix race in task_group() 2012-10-02 10:30:35 -07:00
stats.c sched: Remove sched_switch 2012-01-27 13:28:53 +01:00
stats.h
stop_task.c sched: Fix migration thread runtime bogosity 2012-10-13 05:39:01 +09:00