From: Tejun Heo <tj@kernel.org> To: Michal Hocko <mhocko@kernel.org> Cc: Johannes Weiner <hannes@cmpxchg.org>, Petr Mladek <pmladek@suse.com>, cgroups@vger.kernel.org, Cyril Hrubis <chrubis@suse.cz>, linux-kernel@vger.kernel.org Subject: [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Date: Thu, 21 Apr 2016 19:06:48 -0400 [thread overview] Message-ID: <20160421230648.GI4775@htj.duckdns.org> (raw) In-Reply-To: <20160417120747.GC21757@dhcp22.suse.cz> 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 --- include/linux/cgroup-defs.h | 1 + include/linux/cpuset.h | 6 ------ kernel/cgroup.c | 7 +++++-- kernel/cpuset.c | 4 ++-- 4 files changed, 8 insertions(+), 10 deletions(-) --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -444,6 +444,7 @@ struct cgroup_subsys { int (*can_attach)(struct cgroup_taskset *tset); void (*cancel_attach)(struct cgroup_taskset *tset); void (*attach)(struct cgroup_taskset *tset); + void (*post_attach)(void); int (*can_fork)(struct task_struct *task); void (*cancel_fork)(struct task_struct *task); void (*fork)(struct task_struct *task); --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -137,8 +137,6 @@ static inline void set_mems_allowed(node task_unlock(current); } -extern void cpuset_post_attach_flush(void); - #else /* !CONFIG_CPUSETS */ static inline bool cpusets_enabled(void) { return false; } @@ -245,10 +243,6 @@ static inline bool read_mems_allowed_ret return false; } -static inline void cpuset_post_attach_flush(void) -{ -} - #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2825,9 +2825,10 @@ static ssize_t __cgroup_procs_write(stru 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; } --- 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_ } } -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,
WARNING: multiple messages have this Message-ID (diff)
From: Tejun Heo <tj-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> To: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org>, Petr Mladek <pmladek-IBi9RG/b67k@public.gmane.org>, cgroups-u79uwXL29TY76Z2rM5mHXA@public.gmane.org, Cyril Hrubis <chrubis-AlSwsSmVLrQ@public.gmane.org>, linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Subject: [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Date: Thu, 21 Apr 2016 19:06:48 -0400 [thread overview] Message-ID: <20160421230648.GI4775@htj.duckdns.org> (raw) In-Reply-To: <20160417120747.GC21757-2MMpYkNvuYDjFM9bn6wA6Q@public.gmane.org> 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-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: Li Zefan <lizefan-hv44wF8Li93QT0dZR+AlfA@public.gmane.org> Cc: Johannes Weiner <hannes-druUgvl0LCNAfugRpC6u6w@public.gmane.org> Cc: Michal Hocko <mhocko-DgEjT+Ai2ygdnm+yROfE0A@public.gmane.org> Cc: <stable-u79uwXL29TY76Z2rM5mHXA@public.gmane.org> # 4.4+ prerequisite for the next patch --- include/linux/cgroup-defs.h | 1 + include/linux/cpuset.h | 6 ------ kernel/cgroup.c | 7 +++++-- kernel/cpuset.c | 4 ++-- 4 files changed, 8 insertions(+), 10 deletions(-) --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -444,6 +444,7 @@ struct cgroup_subsys { int (*can_attach)(struct cgroup_taskset *tset); void (*cancel_attach)(struct cgroup_taskset *tset); void (*attach)(struct cgroup_taskset *tset); + void (*post_attach)(void); int (*can_fork)(struct task_struct *task); void (*cancel_fork)(struct task_struct *task); void (*fork)(struct task_struct *task); --- a/include/linux/cpuset.h +++ b/include/linux/cpuset.h @@ -137,8 +137,6 @@ static inline void set_mems_allowed(node task_unlock(current); } -extern void cpuset_post_attach_flush(void); - #else /* !CONFIG_CPUSETS */ static inline bool cpusets_enabled(void) { return false; } @@ -245,10 +243,6 @@ static inline bool read_mems_allowed_ret return false; } -static inline void cpuset_post_attach_flush(void) -{ -} - #endif /* !CONFIG_CPUSETS */ #endif /* _LINUX_CPUSET_H */ --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2825,9 +2825,10 @@ static ssize_t __cgroup_procs_write(stru 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; } --- 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_ } } -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,
next prev parent reply other threads:[~2016-04-21 23:06 UTC|newest] Thread overview: 56+ messages / expand[flat|nested] mbox.gz Atom feed top 2016-04-13 9:42 [BUG] cgroup/workques/fork: deadlock when moving cgroups Petr Mladek 2016-04-13 18:33 ` Tejun Heo 2016-04-13 18:33 ` Tejun Heo 2016-04-13 18:57 ` Tejun Heo 2016-04-13 18:57 ` Tejun Heo 2016-04-13 19:23 ` Michal Hocko 2016-04-13 19:23 ` Michal Hocko 2016-04-13 19:28 ` Michal Hocko 2016-04-13 19:28 ` Michal Hocko 2016-04-13 19:37 ` Tejun Heo 2016-04-13 19:48 ` Michal Hocko 2016-04-14 7:06 ` Michal Hocko 2016-04-14 7:06 ` Michal Hocko 2016-04-14 15:32 ` Tejun Heo 2016-04-14 15:32 ` Tejun Heo 2016-04-14 17:50 ` Johannes Weiner 2016-04-15 7:06 ` Michal Hocko 2016-04-15 14:38 ` Tejun Heo 2016-04-15 14:38 ` Tejun Heo 2016-04-15 15:08 ` Michal Hocko 2016-04-15 15:08 ` Michal Hocko 2016-04-15 15:25 ` Tejun Heo 2016-04-15 15:25 ` Tejun Heo 2016-04-17 12:00 ` Michal Hocko 2016-04-17 12:00 ` Michal Hocko 2016-04-18 14:40 ` Petr Mladek 2016-04-18 14:40 ` Petr Mladek 2016-04-19 14:01 ` Michal Hocko 2016-04-19 14:01 ` Michal Hocko 2016-04-19 15:39 ` Petr Mladek 2016-04-15 19:17 ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo 2016-04-17 12:07 ` Michal Hocko 2016-04-17 12:07 ` Michal Hocko 2016-04-20 21:29 ` Tejun Heo 2016-04-20 21:29 ` Tejun Heo 2016-04-21 3:27 ` Michal Hocko 2016-04-21 3:27 ` Michal Hocko 2016-04-21 15:00 ` Petr Mladek 2016-04-21 15:00 ` Petr Mladek 2016-04-21 15:51 ` Tejun Heo 2016-04-21 23:06 ` Tejun Heo [this message] 2016-04-21 23:06 ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo 2016-04-21 23:09 ` [PATCH 2/2] memcg: relocate charge moving from ->attach to ->post_attach Tejun Heo 2016-04-21 23:09 ` Tejun Heo 2016-04-22 13:57 ` Petr Mladek 2016-04-22 13:57 ` Petr Mladek 2016-04-25 8:25 ` Michal Hocko 2016-04-25 8:25 ` Michal Hocko 2016-04-25 19:42 ` Tejun Heo 2016-04-25 19:42 ` Tejun Heo 2016-04-25 19:44 ` Tejun Heo 2016-04-25 19:44 ` Tejun Heo 2016-04-21 23:11 ` [PATCH 1/2] cgroup, cpuset: replace cpuset_post_attach_flush() with cgroup_subsys->post_attach callback Tejun Heo 2016-04-21 23:11 ` Tejun Heo 2016-04-21 15:56 ` [PATCH for-4.6-fixes] memcg: remove lru_add_drain_all() invocation from mem_cgroup_move_charge() Tejun Heo 2016-04-21 15:56 ` Tejun Heo
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