From f1c6f1a7eed963ed233ba4c8b6fa8addb86c6ddc Mon Sep 17 00:00:00 2001 From: Carsten Emde Date: Wed, 26 Oct 2011 23:14:16 +0200 Subject: sched: Set the command name of the idle tasks in SMP kernels In UP systems, the idle task is initialized using the init_task structure from which the command name is taken (currently "swapper"). In SMP systems, one idle task per CPU is forked by the worker thread from which the task structure is copied. The command name is, therefore, "kworker/0:0" or "kworker/0:1", if not updated. Since such update was lacking, all idle tasks in SMP systems were incorrectly named. This longtime bug was not discovered immediately, because there is no /proc/0 entry - the bug only becomes apparent when tracing is enabled. This patch sets the command name of the idle tasks in SMP systems to the name that is used in the INIT_TASK structure suffixed by a slash and the number of the CPU. Signed-off-by: Carsten Emde Signed-off-by: Peter Zijlstra Link: http://lkml.kernel.org/r/20111026211708.768925506@osadl.org Signed-off-by: Ingo Molnar --- include/linux/init_task.h | 4 +++- 1 file changed, 3 insertions(+), 1 deletion(-) (limited to 'include/linux/init_task.h') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 08ffab01e76c..b6e5b8b000e0 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -126,6 +126,8 @@ extern struct cred init_cred; # define INIT_PERF_EVENTS(tsk) #endif +#define INIT_TASK_COMM "swapper" + /* * INIT_TASK is used to set up the first task table, touch at * your own risk!. Base=0, limit=0x1fffff (=2MB) @@ -162,7 +164,7 @@ extern struct cred init_cred; .group_leader = &tsk, \ RCU_INIT_POINTER(.real_cred, &init_cred), \ RCU_INIT_POINTER(.cred, &init_cred), \ - .comm = "swapper", \ + .comm = INIT_TASK_COMM, \ .thread = INIT_THREAD, \ .fs = &init_fs, \ .files = &init_files, \ -- cgit v1.2.3 From 257058ae2b971646b96ab3a15605ac69186e562a Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Mon, 12 Dec 2011 18:12:21 -0800 Subject: threadgroup: rename signal->threadgroup_fork_lock to ->group_rwsem Make the following renames to prepare for extension of threadgroup locking. * s/signal->threadgroup_fork_lock/signal->group_rwsem/ * s/threadgroup_fork_read_lock()/threadgroup_change_begin()/ * s/threadgroup_fork_read_unlock()/threadgroup_change_end()/ * s/threadgroup_fork_write_lock()/threadgroup_lock()/ * s/threadgroup_fork_write_unlock()/threadgroup_unlock()/ This patch doesn't cause any behavior change. -v2: Rename threadgroup_change_done() to threadgroup_change_end() per KAMEZAWA's suggestion. Signed-off-by: Tejun Heo Reviewed-by: KAMEZAWA Hiroyuki Acked-by: Li Zefan Cc: Oleg Nesterov Cc: Andrew Morton Cc: Paul Menage --- include/linux/init_task.h | 9 ++++----- include/linux/sched.h | 30 +++++++++++++++--------------- kernel/cgroup.c | 13 ++++++------- kernel/fork.c | 8 ++++---- 4 files changed, 29 insertions(+), 31 deletions(-) (limited to 'include/linux/init_task.h') diff --git a/include/linux/init_task.h b/include/linux/init_task.h index 94b1e356c02a..f4544b99efe4 100644 --- a/include/linux/init_task.h +++ b/include/linux/init_task.h @@ -23,11 +23,10 @@ extern struct files_struct init_files; extern struct fs_struct init_fs; #ifdef CONFIG_CGROUPS -#define INIT_THREADGROUP_FORK_LOCK(sig) \ - .threadgroup_fork_lock = \ - __RWSEM_INITIALIZER(sig.threadgroup_fork_lock), +#define INIT_GROUP_RWSEM(sig) \ + .group_rwsem = __RWSEM_INITIALIZER(sig.group_rwsem), #else -#define INIT_THREADGROUP_FORK_LOCK(sig) +#define INIT_GROUP_RWSEM(sig) #endif #define INIT_SIGNALS(sig) { \ @@ -46,7 +45,7 @@ extern struct fs_struct init_fs; }, \ .cred_guard_mutex = \ __MUTEX_INITIALIZER(sig.cred_guard_mutex), \ - INIT_THREADGROUP_FORK_LOCK(sig) \ + INIT_GROUP_RWSEM(sig) \ } extern struct nsproxy init_nsproxy; diff --git a/include/linux/sched.h b/include/linux/sched.h index d81cce933869..8cd523202a3b 100644 --- a/include/linux/sched.h +++ b/include/linux/sched.h @@ -635,13 +635,13 @@ struct signal_struct { #endif #ifdef CONFIG_CGROUPS /* - * The threadgroup_fork_lock prevents threads from forking with + * The group_rwsem prevents threads from forking with * CLONE_THREAD while held for writing. Use this for fork-sensitive * threadgroup-wide operations. It's taken for reading in fork.c in * copy_process(). * Currently only needed write-side by cgroups. */ - struct rw_semaphore threadgroup_fork_lock; + struct rw_semaphore group_rwsem; #endif int oom_adj; /* OOM kill score adjustment (bit shift) */ @@ -2371,29 +2371,29 @@ static inline void unlock_task_sighand(struct task_struct *tsk, spin_unlock_irqrestore(&tsk->sighand->siglock, *flags); } -/* See the declaration of threadgroup_fork_lock in signal_struct. */ +/* See the declaration of group_rwsem in signal_struct. */ #ifdef CONFIG_CGROUPS -static inline void threadgroup_fork_read_lock(struct task_struct *tsk) +static inline void threadgroup_change_begin(struct task_struct *tsk) { - down_read(&tsk->signal->threadgroup_fork_lock); + down_read(&tsk->signal->group_rwsem); } -static inline void threadgroup_fork_read_unlock(struct task_struct *tsk) +static inline void threadgroup_change_end(struct task_struct *tsk) { - up_read(&tsk->signal->threadgroup_fork_lock); + up_read(&tsk->signal->group_rwsem); } -static inline void threadgroup_fork_write_lock(struct task_struct *tsk) +static inline void threadgroup_lock(struct task_struct *tsk) { - down_write(&tsk->signal->threadgroup_fork_lock); + down_write(&tsk->signal->group_rwsem); } -static inline void threadgroup_fork_write_unlock(struct task_struct *tsk) +static inline void threadgroup_unlock(struct task_struct *tsk) { - up_write(&tsk->signal->threadgroup_fork_lock); + up_write(&tsk->signal->group_rwsem); } #else -static inline void threadgroup_fork_read_lock(struct task_struct *tsk) {} -static inline void threadgroup_fork_read_unlock(struct task_struct *tsk) {} -static inline void threadgroup_fork_write_lock(struct task_struct *tsk) {} -static inline void threadgroup_fork_write_unlock(struct task_struct *tsk) {} +static inline void threadgroup_change_begin(struct task_struct *tsk) {} +static inline void threadgroup_change_end(struct task_struct *tsk) {} +static inline void threadgroup_lock(struct task_struct *tsk) {} +static inline void threadgroup_unlock(struct task_struct *tsk) {} #endif #ifndef __HAVE_THREAD_FUNCTIONS diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 6545fd61b10d..b409df3b2e9d 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -2003,8 +2003,8 @@ static int css_set_prefetch(struct cgroup *cgrp, struct css_set *cg, * @cgrp: the cgroup to attach to * @leader: the threadgroup leader task_struct of the group to be attached * - * Call holding cgroup_mutex and the threadgroup_fork_lock of the leader. Will - * take task_lock of each thread in leader's threadgroup individually in turn. + * Call holding cgroup_mutex and the group_rwsem of the leader. Will take + * task_lock of each thread in leader's threadgroup individually in turn. */ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) { @@ -2030,8 +2030,8 @@ int cgroup_attach_proc(struct cgroup *cgrp, struct task_struct *leader) * step 0: in order to do expensive, possibly blocking operations for * every thread, we cannot iterate the thread group list, since it needs * rcu or tasklist locked. instead, build an array of all threads in the - * group - threadgroup_fork_lock prevents new threads from appearing, - * and if threads exit, this will just be an over-estimate. + * group - group_rwsem prevents new threads from appearing, and if + * threads exit, this will just be an over-estimate. */ group_size = get_nr_threads(leader); /* flex_array supports very large thread-groups better than kmalloc. */ @@ -2249,7 +2249,6 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) cgroup_unlock(); return -ESRCH; } - /* * even if we're attaching all tasks in the thread group, we * only need to check permissions on one of them. @@ -2273,9 +2272,9 @@ static int attach_task_by_pid(struct cgroup *cgrp, u64 pid, bool threadgroup) } if (threadgroup) { - threadgroup_fork_write_lock(tsk); + threadgroup_lock(tsk); ret = cgroup_attach_proc(cgrp, tsk); - threadgroup_fork_write_unlock(tsk); + threadgroup_unlock(tsk); } else { ret = cgroup_attach_task(cgrp, tsk); } diff --git a/kernel/fork.c b/kernel/fork.c index 827808613847..d4ac9e3e0075 100644 --- a/kernel/fork.c +++ b/kernel/fork.c @@ -972,7 +972,7 @@ static int copy_signal(unsigned long clone_flags, struct task_struct *tsk) sched_autogroup_fork(sig); #ifdef CONFIG_CGROUPS - init_rwsem(&sig->threadgroup_fork_lock); + init_rwsem(&sig->group_rwsem); #endif sig->oom_adj = current->signal->oom_adj; @@ -1157,7 +1157,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, p->io_context = NULL; p->audit_context = NULL; if (clone_flags & CLONE_THREAD) - threadgroup_fork_read_lock(current); + threadgroup_change_begin(current); cgroup_fork(p); #ifdef CONFIG_NUMA p->mempolicy = mpol_dup(p->mempolicy); @@ -1372,7 +1372,7 @@ static struct task_struct *copy_process(unsigned long clone_flags, proc_fork_connector(p); cgroup_post_fork(p); if (clone_flags & CLONE_THREAD) - threadgroup_fork_read_unlock(current); + threadgroup_change_end(current); perf_event_fork(p); return p; @@ -1407,7 +1407,7 @@ bad_fork_cleanup_policy: bad_fork_cleanup_cgroup: #endif if (clone_flags & CLONE_THREAD) - threadgroup_fork_read_unlock(current); + threadgroup_change_end(current); cgroup_exit(p, cgroup_callbacks_done); delayacct_tsk_free(p); module_put(task_thread_info(p)->exec_domain->module); -- cgit v1.2.3