The patch titled
cgroups: change css_set freeing mechanism to be under RCU
has been added to the -mm tree. Its filename is
cgroups-change-css_set-freeing-mechanism-to-be-under-rcu.patch
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------------------------------------------------------
Subject: cgroups: change css_set freeing mechanism to be under RCU
From: Ben Blum <bblum@xxxxxxxxxx>
Changes css_set freeing mechanism to be under RCU
This is a prepatch for making the procs file writable. In order to free the
old css_sets for each task to be moved as they're being moved, the freeing
mechanism must be RCU-protected, or else we would have to have a call to
synchronize_rcu() for each task before freeing its old css_set.
Signed-off-by: Ben Blum <bblum@xxxxxxxxxx>
Signed-off-by: Paul Menage <menage@xxxxxxxxxx>
Cc: "Paul E. McKenney" <paulmck@xxxxxxxxxx>
Acked-by: Li Zefan <lizf@xxxxxxxxxxxxxx>
Cc: Matt Helsley <matthltc@xxxxxxxxxx>
Cc: "Eric W. Biederman" <ebiederm@xxxxxxxxxxxx>
Cc: Oleg Nesterov <oleg@xxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
include/linux/cgroup.h | 3 +++
kernel/cgroup.c | 8 +++++++-
2 files changed, 10 insertions(+), 1 deletion(-)
diff -puN include/linux/cgroup.h~cgroups-change-css_set-freeing-mechanism-to-be-under-rcu include/linux/cgroup.h
--- a/include/linux/cgroup.h~cgroups-change-css_set-freeing-mechanism-to-be-under-rcu
+++ a/include/linux/cgroup.h
@@ -260,6 +260,9 @@ struct css_set {
* during subsystem registration (at boot time).
*/
struct cgroup_subsys_state *subsys[CGROUP_SUBSYS_COUNT];
+
+ /* For RCU-protected deletion */
+ struct rcu_head rcu_head;
};
/*
diff -puN kernel/cgroup.c~cgroups-change-css_set-freeing-mechanism-to-be-under-rcu kernel/cgroup.c
--- a/kernel/cgroup.c~cgroups-change-css_set-freeing-mechanism-to-be-under-rcu
+++ a/kernel/cgroup.c
@@ -267,6 +267,12 @@ static struct hlist_head *css_set_hash(s
return &css_set_table[index];
}
+static void free_css_set_rcu(struct rcu_head *obj)
+{
+ struct css_set *cg = container_of(obj, struct css_set, rcu_head);
+ kfree(cg);
+}
+
/* We don't maintain the lists running through each css_set to its
* task until after the first call to cgroup_iter_start(). This
* reduces the fork()/exit() overhead for people who have cgroups
@@ -310,7 +316,7 @@ static void __put_css_set(struct css_set
}
write_unlock(&css_set_lock);
- kfree(cg);
+ call_rcu(&cg->rcu_head, free_css_set_rcu);
}
/*
_
Patches currently in -mm which might be from bblum@xxxxxxxxxx are
cgroups-add-a-read-only-procs-file-similar-to-tasks-that-shows-only-unique-tgids.patch
cgroups-ensure-correct-concurrent-opening-reading-of-pidlists-across-pid-namespaces.patch
cgroups-use-vmalloc-for-large-cgroups-pidlist-allocations.patch
cgroups-change-css_set-freeing-mechanism-to-be-under-rcu.patch
cgroups-let-ss-can_attach-and-ss-attach-do-whole-threadgroups-at-a-time.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup.patch
cgroups-add-functionality-to-read-write-lock-clone_thread-forking-per-threadgroup-fix.patch
cgroups-add-ability-to-move-all-threads-in-a-process-to-a-new-cgroup-atomically.patch
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