The patch titled
cgroup: introduce cancel_attach()
has been added to the -mm tree. Its filename is
cgroup-introduce-cancel_attach.patch
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------------------------------------------------------
Subject: cgroup: introduce cancel_attach()
From: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Add cancel_attach() operation to struct cgroup_subsys. cancel_attach()
can be used when can_attach() operation prepares something for the subsys,
but we should rollback what can_attach() operation has prepared if attach
task fails after we've succeeded in can_attach().
Signed-off-by: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Reviewed-by: Paul Menage <menage@xxxxxxxxxx>
Cc: Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx>
Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@xxxxxxxxxxxxxx>
Cc: Daisuke Nishimura <nishimura@xxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/cgroups/cgroups.txt | 13 ++++++++-
include/linux/cgroup.h | 2 +
kernel/cgroup.c | 40 +++++++++++++++++++++++-----
3 files changed, 47 insertions(+), 8 deletions(-)
diff -puN Documentation/cgroups/cgroups.txt~cgroup-introduce-cancel_attach Documentation/cgroups/cgroups.txt
--- a/Documentation/cgroups/cgroups.txt~cgroup-introduce-cancel_attach
+++ a/Documentation/cgroups/cgroups.txt
@@ -536,10 +536,21 @@ returns an error, this will abort the at
task is passed, then a successful result indicates that *any*
unspecified task can be moved into the cgroup. Note that this isn't
called on a fork. If this method returns 0 (success) then this should
-remain valid while the caller holds cgroup_mutex. If threadgroup is
+remain valid while the caller holds cgroup_mutex and it is ensured that either
+attach() or cancel_attach() will be called in future. If threadgroup is
true, then a successful result indicates that all threads in the given
thread's threadgroup can be moved together.
+void cancel_attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ struct task_struct *task, bool threadgroup)
+(cgroup_mutex held by caller)
+
+Called when a task attach operation has failed after can_attach() has succeeded.
+A subsystem whose can_attach() has some side-effects should provide this
+function, so that the subsytem can implement a rollback. If not, not necessary.
+This will be called only about subsystems whose can_attach() operation have
+succeeded.
+
void attach(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup *old_cgrp, struct task_struct *task,
bool threadgroup)
diff -puN include/linux/cgroup.h~cgroup-introduce-cancel_attach include/linux/cgroup.h
--- a/include/linux/cgroup.h~cgroup-introduce-cancel_attach
+++ a/include/linux/cgroup.h
@@ -427,6 +427,8 @@ struct cgroup_subsys {
void (*destroy)(struct cgroup_subsys *ss, struct cgroup *cgrp);
int (*can_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct task_struct *tsk, bool threadgroup);
+ void (*cancel_attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
+ struct task_struct *tsk, bool threadgroup);
void (*attach)(struct cgroup_subsys *ss, struct cgroup *cgrp,
struct cgroup *old_cgrp, struct task_struct *tsk,
bool threadgroup);
diff -puN kernel/cgroup.c~cgroup-introduce-cancel_attach kernel/cgroup.c
--- a/kernel/cgroup.c~cgroup-introduce-cancel_attach
+++ a/kernel/cgroup.c
@@ -1539,7 +1539,7 @@ int cgroup_path(const struct cgroup *cgr
int cgroup_attach_task(struct cgroup *cgrp, struct task_struct *tsk)
{
int retval = 0;
- struct cgroup_subsys *ss;
+ struct cgroup_subsys *ss, *failed_ss = NULL;
struct cgroup *oldcgrp;
struct css_set *cg;
struct css_set *newcg;
@@ -1553,8 +1553,16 @@ int cgroup_attach_task(struct cgroup *cg
for_each_subsys(root, ss) {
if (ss->can_attach) {
retval = ss->can_attach(ss, cgrp, tsk, false);
- if (retval)
- return retval;
+ if (retval) {
+ /*
+ * Remember on which subsystem the can_attach()
+ * failed, so that we only call cancel_attach()
+ * against the subsystems whose can_attach()
+ * succeeded. (See below)
+ */
+ failed_ss = ss;
+ goto out;
+ }
}
}
@@ -1568,14 +1576,17 @@ int cgroup_attach_task(struct cgroup *cg
*/
newcg = find_css_set(cg, cgrp);
put_css_set(cg);
- if (!newcg)
- return -ENOMEM;
+ if (!newcg) {
+ retval = -ENOMEM;
+ goto out;
+ }
task_lock(tsk);
if (tsk->flags & PF_EXITING) {
task_unlock(tsk);
put_css_set(newcg);
- return -ESRCH;
+ retval = -ESRCH;
+ goto out;
}
rcu_assign_pointer(tsk->cgroups, newcg);
task_unlock(tsk);
@@ -1601,7 +1612,22 @@ int cgroup_attach_task(struct cgroup *cg
* is no longer empty.
*/
cgroup_wakeup_rmdir_waiter(cgrp);
- return 0;
+out:
+ if (retval) {
+ for_each_subsys(root, ss) {
+ if (ss == failed_ss)
+ /*
+ * This subsystem was the one that failed the
+ * can_attach() check earlier, so we don't need
+ * to call cancel_attach() against it or any
+ * remaining subsystems.
+ */
+ break;
+ if (ss->cancel_attach)
+ ss->cancel_attach(ss, cgrp, tsk, false);
+ }
+ }
+ return retval;
}
/*
_
Patches currently in -mm which might be from nishimura@xxxxxxxxxxxxxxxxx are
cgroup-introduce-cancel_attach.patch
cgroup-introduce-coalesce-css_get-and-css_put.patch
memcg-add-interface-to-move-charge-at-task-migration.patch
memcg-move-charges-of-anonymous-page.patch
memcg-move-charges-of-anonymous-page-cleanup.patch
memcg-improve-performance-in-moving-charge.patch
memcg-avoid-oom-during-moving-charge.patch
memcg-move-charges-of-anonymous-swap.patch
memcg-improve-performance-in-moving-swap-charge.patch
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