linux_dsm_epyc7002/include
Li Zefan 0ab02ca8f8 cgroup: protect modifications to cgroup_idr with cgroup_mutex
Setup cgroupfs like this:
  # mount -t cgroup -o cpuacct xxx /cgroup
  # mkdir /cgroup/sub1
  # mkdir /cgroup/sub2

Then run these two commands:
  # for ((; ;)) { mkdir /cgroup/sub1/tmp && rmdir /mnt/sub1/tmp; } &
  # for ((; ;)) { mkdir /cgroup/sub2/tmp && rmdir /mnt/sub2/tmp; } &

After seconds you may see this warning:

------------[ cut here ]------------
WARNING: CPU: 1 PID: 25243 at lib/idr.c:527 sub_remove+0x87/0x1b0()
idr_remove called for id=6 which is not allocated.
...
Call Trace:
 [<ffffffff8156063c>] dump_stack+0x7a/0x96
 [<ffffffff810591ac>] warn_slowpath_common+0x8c/0xc0
 [<ffffffff81059296>] warn_slowpath_fmt+0x46/0x50
 [<ffffffff81300aa7>] sub_remove+0x87/0x1b0
 [<ffffffff810f3f02>] ? css_killed_work_fn+0x32/0x1b0
 [<ffffffff81300bf5>] idr_remove+0x25/0xd0
 [<ffffffff810f2bab>] cgroup_destroy_css_killed+0x5b/0xc0
 [<ffffffff810f4000>] css_killed_work_fn+0x130/0x1b0
 [<ffffffff8107cdbc>] process_one_work+0x26c/0x550
 [<ffffffff8107eefe>] worker_thread+0x12e/0x3b0
 [<ffffffff81085f96>] kthread+0xe6/0xf0
 [<ffffffff81570bac>] ret_from_fork+0x7c/0xb0
---[ end trace 2d1577ec10cf80d0 ]---

It's because allocating/removing cgroup ID is not properly synchronized.

The bug was introduced when we converted cgroup_ida to cgroup_idr.
While synchronization is already done inside ida_simple_{get,remove}(),
users are responsible for concurrent calls to idr_{alloc,remove}().

tj: Refreshed on top of b58c89986a ("cgroup: fix error return from
cgroup_create()").

Fixes: 4e96ee8e98 ("cgroup: convert cgroup_ida to cgroup_idr")
Cc: <stable@vger.kernel.org> #3.12+
Reported-by: Michal Hocko <mhocko@suse.cz>
Signed-off-by: Li Zefan <lizefan@huawei.com>
Signed-off-by: Tejun Heo <tj@kernel.org>
2014-02-11 10:38:30 -05:00
..
acpi Merge branches 'acpi-processor', 'acpi-hotplug', 'acpi-init', 'acpi-pm' and 'acpica' 2014-01-29 11:47:18 +01:00
asm-generic Merge branch 'merge' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-27 21:03:39 -08:00
clocksource
crypto
drm drm/tegra: Changes for v3.14-rc1 (update) 2014-01-29 12:03:56 +10:00
dt-bindings Merge branch 'next' of git://git.kernel.org/pub/scm/linux/kernel/git/benh/powerpc 2014-01-30 17:07:18 -08:00
keys
kvm
linux cgroup: protect modifications to cgroup_idr with cgroup_mutex 2014-02-11 10:38:30 -05:00
math-emu
media
memory
misc
net Merge git://git.kernel.org/pub/scm/linux/kernel/git/davem/net-next 2014-01-25 11:17:34 -08:00
pcmcia
ras
rdma Merge branch 'ip-roce' into for-next 2014-01-22 23:24:21 -08:00
rxrpc
scsi Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-01-31 15:31:23 -08:00
sound ARM: SoC board updates for 3.14 2014-01-23 18:48:28 -08:00
target Merge branch 'for-next' of git://git.kernel.org/pub/scm/linux/kernel/git/nab/target-pending 2014-01-31 15:31:23 -08:00
trace Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2014-01-31 09:31:14 -08:00
uapi Merge branch 'v4l_for_linus' of git://git.kernel.org/pub/scm/linux/kernel/git/mchehab/linux-media 2014-01-31 09:31:14 -08:00
video video: pxa168fb: Cleanup pxa168fb.h file 2014-01-17 10:57:43 +02:00
xen Bug-fixes: 2014-01-31 08:38:18 -08:00
Kbuild