1. 25 Sep, 2014 2 commits
  2. 18 Sep, 2014 1 commit
  3. 04 Sep, 2014 2 commits
    • Li Zefan's avatar
      cgroup: check cgroup liveliness before unbreaking kernfs · aa32362f
      Li Zefan authored
      When cgroup_kn_lock_live() is called through some kernfs operation and
      another thread is calling cgroup_rmdir(), we'll trigger the warning in
      cgroup_get().
      
      ------------[ cut here ]------------
      WARNING: CPU: 1 PID: 1228 at kernel/cgroup.c:1034 cgroup_get+0x89/0xa0()
      ...
      Call Trace:
       [<c16ee73d>] dump_stack+0x41/0x52
       [<c10468ef>] warn_slowpath_common+0x7f/0xa0
       [<c104692d>] warn_slowpath_null+0x1d/0x20
       [<c10bb999>] cgroup_get+0x89/0xa0
       [<c10bbe58>] cgroup_kn_lock_live+0x28/0x70
       [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230
       [<c10be5b2>] cgroup_tasks_write+0x12/0x20
       [<c10bb7b0>] cgroup_file_write+0x40/0x130
       [<c11aee71>] kernfs_fop_write+0xd1/0x160
       [<c1148e58>] vfs_write+0x98/0x1e0
       [<c114934d>] SyS_write+0x4d/0xa0
       [<c16f656b>] sysenter_do_call+0x12/0x12
      ---[ end trace 6f2e0c38c2108a74 ]---
      
      Fix this by calling css_tryget() instead of cgroup_get().
      
      v2:
      - move cgroup_tryget() right below cgroup_get() definition. (Tejun)
      
      Cc: <stable@vger.kernel.org> # 3.15+
      Reported-by: default avatarToralf Förster <toralf.foerster@gmx.de>
      Signed-off-by: default avatarZefan Li <lizefan@huawei.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      aa32362f
    • Li Zefan's avatar
      cgroup: delay the clearing of cgrp->kn->priv · a4189487
      Li Zefan authored
      Run these two scripts concurrently:
      
          for ((; ;))
          {
              mkdir /cgroup/sub
              rmdir /cgroup/sub
          }
      
          for ((; ;))
          {
              echo $$ > /cgroup/sub/cgroup.procs
              echo $$ > /cgroup/cgroup.procs
          }
      
      A kernel bug will be triggered:
      
      BUG: unable to handle kernel NULL pointer dereference at 00000038
      IP: [<c10bbd69>] cgroup_put+0x9/0x80
      ...
      Call Trace:
       [<c10bbe19>] cgroup_kn_unlock+0x39/0x50
       [<c10bbe91>] cgroup_kn_lock_live+0x61/0x70
       [<c10be3c1>] __cgroup_procs_write.isra.26+0x51/0x230
       [<c10be5b2>] cgroup_tasks_write+0x12/0x20
       [<c10bb7b0>] cgroup_file_write+0x40/0x130
       [<c11aee71>] kernfs_fop_write+0xd1/0x160
       [<c1148e58>] vfs_write+0x98/0x1e0
       [<c114934d>] SyS_write+0x4d/0xa0
       [<c16f656b>] sysenter_do_call+0x12/0x12
      
      We clear cgrp->kn->priv in the end of cgroup_rmdir(), but another
      concurrent thread can access kn->priv after the clearing.
      
      We should move the clearing to css_release_work_fn(). At that time
      no one is holding reference to the cgroup and no one can gain a new
      reference to access it.
      
      v2:
      - move RCU_INIT_POINTER() into the else block. (Tejun)
      - remove the cgroup_parent() check. (Tejun)
      - update the comment in css_tryget_online_from_dir().
      
      Cc: <stable@vger.kernel.org> # 3.15+
      Reported-by: default avatarToralf Förster <toralf.foerster@gmx.de>
      Signed-off-by: default avatarZefan Li <lizefan@huawei.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      a4189487
  4. 22 Aug, 2014 1 commit
    • Vivek Goyal's avatar
      cgroup: Display legacy cgroup files on default hierarchy · fa8137be
      Vivek Goyal authored
      Kernel command line parameter cgroup__DEVEL__legacy_files_on_dfl forces
      legacy cgroup files to show up on default hierarhcy if susbsystem does
      not have any files defined for default hierarchy.
      
      But this seems to be working only if legacy files are defined in
      ss->legacy_cftypes. If one adds some cftypes later using
      cgroup_add_legacy_cftypes(), these files don't show up on default
      hierarchy.  Update the function accordingly so that the dynamically
      added legacy files also show up in the default hierarchy if the target
      subsystem is also using the base legacy files for the default
      hierarchy.
      
      tj: Patch description and comment updates.
      Signed-off-by: default avatarVivek Goyal <vgoyal@redhat.com>
      Signed-off-by: default avatarTejun Heo <tj@kernel.org>
      fa8137be
  5. 18 Aug, 2014 1 commit
  6. 16 Aug, 2014 33 commits