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authorLinus Torvalds <torvalds@linux-foundation.org>2016-04-27 11:41:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2016-04-27 11:41:14 -0700
commit763cfc86ee8fd728a7cf2334b8d3a897af7a7ade (patch)
treeac6e7ca8d6e72aec60b995e1d9cf5e5431903530 /kernel
parent3118e5f966298c94efb0aade318e8ae463fab714 (diff)
parent264a0ae164bc0e9144bebcd25ff030d067b1a878 (diff)
Merge branch 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup fixes from Tejun Heo: "Two patches to fix a deadlock which can be easily triggered if memcg charge moving is used. This bug was introduced while converting threadgroup locking to a global percpu_rwsem and is caused by cgroup controller task migration path depending on the ability to create new kthreads. cpuset had a similar issue which was fixed by performing heavy-lifting operations asynchronous to task migration. The two patches fix the same issue in memcg in a similar way. The first patch makes the mechanism generic and the second relocates memcg charge moving outside the migration path. Given that we don't want to perform heavy operations while writelocking threadgroup lock anyway, moving them out of the way is a desirable solution. One thing to note is that the problem was difficult to debug because lockdep couldn't figure out the deadlock condition. Looking into how to improve that" * 'for-4.6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: memcg: relocate charge moving from ->attach to ->post_attach cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback
Diffstat (limited to 'kernel')
-rw-r--r--kernel/cgroup.c7
-rw-r--r--kernel/cpuset.c4
2 files changed, 7 insertions, 4 deletions
diff --git a/kernel/cgroup.c b/kernel/cgroup.c
index 671dc05c0b0f..909a7d31ffd3 100644
--- a/kernel/cgroup.c
+++ b/kernel/cgroup.c
@@ -2825,9 +2825,10 @@ static ssize_t __cgroup_procs_write(struct kernfs_open_file *of, char *buf,
size_t nbytes, loff_t off, bool threadgroup)
{
struct task_struct *tsk;
+ struct cgroup_subsys *ss;
struct cgroup *cgrp;
pid_t pid;
- int ret;
+ int ssid, ret;
if (kstrtoint(strstrip(buf), 0, &pid) || pid < 0)
return -EINVAL;
@@ -2875,8 +2876,10 @@ out_unlock_rcu:
rcu_read_unlock();
out_unlock_threadgroup:
percpu_up_write(&cgroup_threadgroup_rwsem);
+ for_each_subsys(ss, ssid)
+ if (ss->post_attach)
+ ss->post_attach();
cgroup_kn_unlock(of->kn);
- cpuset_post_attach_flush();
return ret ?: nbytes;
}
diff --git a/kernel/cpuset.c b/kernel/cpuset.c
index 00ab5c2b7c5b..1902956baba1 100644
--- a/kernel/cpuset.c
+++ b/kernel/cpuset.c
@@ -58,7 +58,6 @@
#include <asm/uaccess.h>
#include <linux/atomic.h>
#include <linux/mutex.h>
-#include <linux/workqueue.h>
#include <linux/cgroup.h>
#include <linux/wait.h>
@@ -1016,7 +1015,7 @@ static void cpuset_migrate_mm(struct mm_struct *mm, const nodemask_t *from,
}
}
-void cpuset_post_attach_flush(void)
+static void cpuset_post_attach(void)
{
flush_workqueue(cpuset_migrate_mm_wq);
}
@@ -2087,6 +2086,7 @@ struct cgroup_subsys cpuset_cgrp_subsys = {
.can_attach = cpuset_can_attach,
.cancel_attach = cpuset_cancel_attach,
.attach = cpuset_attach,
+ .post_attach = cpuset_post_attach,
.bind = cpuset_bind,
.legacy_cftypes = files,
.early_init = true,