Task Control Groups: add fork()/exit() hooks

This adds the necessary hooks to the fork() and exit() paths to ensure
that new children inherit their parent's cgroup assignments, and that
exiting processes release reference counts on their cgroups.

Signed-off-by: Paul Menage <menage@google.com>
Cc: Serge E. Hallyn <serue@us.ibm.com>
Cc: "Eric W. Biederman" <ebiederm@xmission.com>
Cc: Dave Hansen <haveblue@us.ibm.com>
Cc: Balbir Singh <balbir@in.ibm.com>
Cc: Paul Jackson <pj@sgi.com>
Cc: Kirill Korotaev <dev@openvz.org>
Cc: Herbert Poetzl <herbert@13thfloor.at>
Cc: Srivatsa Vaddagiri <vatsa@in.ibm.com>
Cc: Cedric Le Goater <clg@fr.ibm.com>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>

1 files changed, 12 insertions, 2 deletions

diff --git a/kernel/fork.c b/kernel/fork.c
index 2ce28f165e3..e7c181454dc 100644
--- a/kernel/fork.c
+++ b/kernel/fork.c
@@ -30,6 +30,7 @@
 #include <linux/capability.h>
 #include <linux/cpu.h>
 #include <linux/cpuset.h>
+#include <linux/cgroup.h>
 #include <linux/security.h>
 #include <linux/swap.h>
 #include <linux/syscalls.h>
@@ -979,6 +980,7 @@ static struct task_struct *copy_process(unsigned long clone_flags,
 {
         int retval;
         struct task_struct *p = NULL;
+        int cgroup_callbacks_done = 0;
 
         if ((clone_flags & (CLONE_NEWNS|CLONE_FS)) == (CLONE_NEWNS|CLONE_FS))
                 return ERR_PTR(-EINVAL);
@@ -1088,12 +1090,13 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         p->io_context = NULL;
         p->audit_context = NULL;
         cpuset_fork(p);
+        cgroup_fork(p);
 #ifdef CONFIG_NUMA
         p->mempolicy = mpol_copy(p->mempolicy);
         if (IS_ERR(p->mempolicy)) {
                 retval = PTR_ERR(p->mempolicy);
                 p->mempolicy = NULL;
-                goto bad_fork_cleanup_cpuset;
+                goto bad_fork_cleanup_cgroup;
         }
         mpol_fix_fork_child_flag(p);
 #endif
@@ -1204,6 +1207,12 @@ static struct task_struct *copy_process(unsigned long clone_flags,
         /* Perform scheduler related setup. Assign this task to a CPU. */
         sched_fork(p, clone_flags);
 
+        /* Now that the task is set up, run cgroup callbacks if
+         * necessary. We need to run them before the task is visible
+         * on the tasklist. */
+        cgroup_fork_callbacks(p);
+        cgroup_callbacks_done = 1;
+
         /* Need tasklist lock for parent etc handling! */
         write_lock_irq(&tasklist_lock);
 
@@ -1318,9 +1327,10 @@ bad_fork_cleanup_security:
 bad_fork_cleanup_policy:
 #ifdef CONFIG_NUMA
         mpol_free(p->mempolicy);
-bad_fork_cleanup_cpuset:
+bad_fork_cleanup_cgroup:
 #endif
         cpuset_exit(p);
+        cgroup_exit(p, cgroup_callbacks_done);
 bad_fork_cleanup_delays_binfmt:
         delayacct_tsk_free(p);
         if (p->binfmt)