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| author | Tejun Heo <tj@kernel.org> | 2016-04-21 19:06:48 -0400 |
|---|---|---|
| committer | Tejun Heo <tj@kernel.org> | 2016-04-25 15:45:14 -0400 |
| commit | 5cf1cacb49aee39c3e02ae87068fc3c6430659b0 (patch) | |
| tree | 569518d16093a55169e4ef1cd5399e9a3f620d06 /kernel | |
| parent | bcc981e9ed84c678533299d7eff17d2c81e4d5de (diff) | |
| download | linux-5cf1cacb49aee39c3e02ae87068fc3c6430659b0.tar.bz2 | |
cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback
Since e93ad19d0564 ("cpuset: make mm migration asynchronous"), cpuset
kicks off asynchronous NUMA node migration if necessary during task
migration and flushes it from cpuset_post_attach_flush() which is
called at the end of __cgroup_procs_write(). This is to avoid
performing migration with cgroup_threadgroup_rwsem write-locked which
can lead to deadlock through dependency on kworker creation.
memcg has a similar issue with charge moving, so let's convert it to
an official callback rather than the current one-off cpuset specific
function. This patch adds cgroup_subsys->post_attach callback and
makes cpuset register cpuset_post_attach_flush() as its ->post_attach.
The conversion is mostly one-to-one except that the new callback is
called under cgroup_mutex. This is to guarantee that no other
migration operations are started before ->post_attach callbacks are
finished. cgroup_mutex is one of the outermost mutex in the system
and has never been and shouldn't be a problem. We can add specialized
synchronization around __cgroup_procs_write() but I don't think
there's any noticeable benefit.
Signed-off-by: Tejun Heo <tj@kernel.org>
Cc: Li Zefan <lizefan@huawei.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@kernel.org>
Cc: <stable@vger.kernel.org> # 4.4+ prerequisite for the next patch
Diffstat (limited to 'kernel')
| -rw-r--r-- | kernel/cgroup.c | 7 | ||||
| -rw-r--r-- | kernel/cpuset.c | 4 |
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, |