From 9303e0c4814d2a6afca878cc35433291e862169c Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 23 Mar 2011 16:42:45 -0700 Subject: cpuset: remove unneeded NODEMASK_ALLOC() in cpuset_sprintf_memlist() It's not necessary to copy cpuset->mems_allowed to a buffer allocated by NODEMASK_ALLOC(). Just pass it to nodelist_scnprintf(). As spotted by Paul, a side effect is we fix a bug that the function can return -ENOMEM but the caller doesn't expect negative return value. Therefore change the return value of cpuset_sprintf_cpulist() and cpuset_sprintf_memlist() from int to size_t. Signed-off-by: Li Zefan Acked-by: Paul Menage Acked-by: David Rientjes Cc: Miao Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpuset.c | 24 ++++++++---------------- 1 file changed, 8 insertions(+), 16 deletions(-) (limited to 'kernel/cpuset.c') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index e92e9818903..4683fe728c9 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1610,34 +1610,26 @@ out: * across a page fault. */ -static int cpuset_sprintf_cpulist(char *page, struct cpuset *cs) +static size_t cpuset_sprintf_cpulist(char *page, struct cpuset *cs) { - int ret; + size_t count; mutex_lock(&callback_mutex); - ret = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed); + count = cpulist_scnprintf(page, PAGE_SIZE, cs->cpus_allowed); mutex_unlock(&callback_mutex); - return ret; + return count; } -static int cpuset_sprintf_memlist(char *page, struct cpuset *cs) +static size_t cpuset_sprintf_memlist(char *page, struct cpuset *cs) { - NODEMASK_ALLOC(nodemask_t, mask, GFP_KERNEL); - int retval; - - if (mask == NULL) - return -ENOMEM; + size_t count; mutex_lock(&callback_mutex); - *mask = cs->mems_allowed; + count = nodelist_scnprintf(page, PAGE_SIZE, cs->mems_allowed); mutex_unlock(&callback_mutex); - retval = nodelist_scnprintf(page, PAGE_SIZE, *mask); - - NODEMASK_FREE(mask); - - return retval; + return count; } static ssize_t cpuset_common_file_read(struct cgroup *cont, -- cgit v1.2.3-70-g09d2 From c8163ca8afcac0fc54593fc60d1e1110edbd0eb2 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 23 Mar 2011 16:42:46 -0700 Subject: cpuset: remove unneeded NODEMASK_ALLOC() in cpuset_attach() oldcs->mems_allowed is not modified during cpuset_attach(), so we don't have to copy it to a buffer allocated by NODEMASK_ALLOC(). Just pass it to cpuset_migrate_mm(). Signed-off-by: Li Zefan Cc: Paul Menage Acked-by: David Rientjes Cc: Miao Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpuset.c | 7 ++----- 1 file changed, 2 insertions(+), 5 deletions(-) (limited to 'kernel/cpuset.c') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 4683fe728c9..7f384f4013b 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1438,10 +1438,9 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct mm_struct *mm; struct cpuset *cs = cgroup_cs(cont); struct cpuset *oldcs = cgroup_cs(oldcont); - NODEMASK_ALLOC(nodemask_t, from, GFP_KERNEL); NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL); - if (from == NULL || to == NULL) + if (to == NULL) goto alloc_fail; if (cs == &top_cpuset) { @@ -1463,18 +1462,16 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, } /* change mm; only needs to be done once even if threadgroup */ - *from = oldcs->mems_allowed; *to = cs->mems_allowed; mm = get_task_mm(tsk); if (mm) { mpol_rebind_mm(mm, to); if (is_memory_migrate(cs)) - cpuset_migrate_mm(mm, from, to); + cpuset_migrate_mm(mm, &oldcs->mems_allowed, to); mmput(mm); } alloc_fail: - NODEMASK_FREE(from); NODEMASK_FREE(to); } -- cgit v1.2.3-70-g09d2 From ee24d3797780eee6ffe581a7b78d27896f9b494a Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 23 Mar 2011 16:42:47 -0700 Subject: cpuset: fix unchecked calls to NODEMASK_ALLOC() Those functions that use NODEMASK_ALLOC() can't propagate errno to users, but will fail silently. Fix it by using a static nodemask_t variable for each function, and those variables are protected by cgroup_mutex; [akpm@linux-foundation.org: fix comment spelling, strengthen cgroup_lock comment] Signed-off-by: Li Zefan Cc: Paul Menage Acked-by: David Rientjes Cc: Miao Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpuset.c | 51 ++++++++++++++++----------------------------------- 1 file changed, 16 insertions(+), 35 deletions(-) (limited to 'kernel/cpuset.c') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index 7f384f4013b..e472fe13919 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1015,17 +1015,12 @@ static void cpuset_change_nodemask(struct task_struct *p, struct cpuset *cs; int migrate; const nodemask_t *oldmem = scan->data; - NODEMASK_ALLOC(nodemask_t, newmems, GFP_KERNEL); - - if (!newmems) - return; + static nodemask_t newmems; /* protected by cgroup_mutex */ cs = cgroup_cs(scan->cg); - guarantee_online_mems(cs, newmems); + guarantee_online_mems(cs, &newmems); - cpuset_change_task_nodemask(p, newmems); - - NODEMASK_FREE(newmems); + cpuset_change_task_nodemask(p, &newmems); mm = get_task_mm(p); if (!mm) @@ -1438,41 +1433,35 @@ static void cpuset_attach(struct cgroup_subsys *ss, struct cgroup *cont, struct mm_struct *mm; struct cpuset *cs = cgroup_cs(cont); struct cpuset *oldcs = cgroup_cs(oldcont); - NODEMASK_ALLOC(nodemask_t, to, GFP_KERNEL); - - if (to == NULL) - goto alloc_fail; + static nodemask_t to; /* protected by cgroup_mutex */ if (cs == &top_cpuset) { cpumask_copy(cpus_attach, cpu_possible_mask); } else { guarantee_online_cpus(cs, cpus_attach); } - guarantee_online_mems(cs, to); + guarantee_online_mems(cs, &to); /* do per-task migration stuff possibly for each in the threadgroup */ - cpuset_attach_task(tsk, to, cs); + cpuset_attach_task(tsk, &to, cs); if (threadgroup) { struct task_struct *c; rcu_read_lock(); list_for_each_entry_rcu(c, &tsk->thread_group, thread_group) { - cpuset_attach_task(c, to, cs); + cpuset_attach_task(c, &to, cs); } rcu_read_unlock(); } /* change mm; only needs to be done once even if threadgroup */ - *to = cs->mems_allowed; + to = cs->mems_allowed; mm = get_task_mm(tsk); if (mm) { - mpol_rebind_mm(mm, to); + mpol_rebind_mm(mm, &to); if (is_memory_migrate(cs)) - cpuset_migrate_mm(mm, &oldcs->mems_allowed, to); + cpuset_migrate_mm(mm, &oldcs->mems_allowed, &to); mmput(mm); } - -alloc_fail: - NODEMASK_FREE(to); } /* The various types of files and directories in a cpuset file system */ @@ -2055,10 +2044,7 @@ static void scan_for_empty_cpusets(struct cpuset *root) struct cpuset *cp; /* scans cpusets being updated */ struct cpuset *child; /* scans child cpusets of cp */ struct cgroup *cont; - NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL); - - if (oldmems == NULL) - return; + static nodemask_t oldmems; /* protected by cgroup_mutex */ list_add_tail((struct list_head *)&root->stack_list, &queue); @@ -2075,7 +2061,7 @@ static void scan_for_empty_cpusets(struct cpuset *root) nodes_subset(cp->mems_allowed, node_states[N_HIGH_MEMORY])) continue; - *oldmems = cp->mems_allowed; + oldmems = cp->mems_allowed; /* Remove offline cpus and mems from this cpuset. */ mutex_lock(&callback_mutex); @@ -2091,10 +2077,9 @@ static void scan_for_empty_cpusets(struct cpuset *root) remove_tasks_in_empty_cpuset(cp); else { update_tasks_cpumask(cp, NULL); - update_tasks_nodemask(cp, oldmems, NULL); + update_tasks_nodemask(cp, &oldmems, NULL); } } - NODEMASK_FREE(oldmems); } /* @@ -2136,19 +2121,16 @@ void cpuset_update_active_cpus(void) static int cpuset_track_online_nodes(struct notifier_block *self, unsigned long action, void *arg) { - NODEMASK_ALLOC(nodemask_t, oldmems, GFP_KERNEL); - - if (oldmems == NULL) - return NOTIFY_DONE; + static nodemask_t oldmems; /* protected by cgroup_mutex */ cgroup_lock(); switch (action) { case MEM_ONLINE: - *oldmems = top_cpuset.mems_allowed; + oldmems = top_cpuset.mems_allowed; mutex_lock(&callback_mutex); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; mutex_unlock(&callback_mutex); - update_tasks_nodemask(&top_cpuset, oldmems, NULL); + update_tasks_nodemask(&top_cpuset, &oldmems, NULL); break; case MEM_OFFLINE: /* @@ -2162,7 +2144,6 @@ static int cpuset_track_online_nodes(struct notifier_block *self, } cgroup_unlock(); - NODEMASK_FREE(oldmems); return NOTIFY_OK; } #endif -- cgit v1.2.3-70-g09d2 From 523fb486bfd94e3a3b16a42bcb21b1959cf14df8 Mon Sep 17 00:00:00 2001 From: Li Zefan Date: Wed, 23 Mar 2011 16:42:48 -0700 Subject: cpuset: hold callback_mutex in cpuset_post_clone() Chaning cpuset->mems/cpuset->cpus should be protected under callback_mutex. cpuset_clone() doesn't follow this rule. It's ok because it's called when creating and initializing a cgroup, but we'd better hold the lock to avoid subtil break in the future. Signed-off-by: Li Zefan Acked-by: Paul Menage Acked-by: David Rientjes Cc: Miao Xie Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- kernel/cpuset.c | 2 ++ 1 file changed, 2 insertions(+) (limited to 'kernel/cpuset.c') diff --git a/kernel/cpuset.c b/kernel/cpuset.c index e472fe13919..33eee16addb 100644 --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -1840,8 +1840,10 @@ static void cpuset_post_clone(struct cgroup_subsys *ss, cs = cgroup_cs(cgroup); parent_cs = cgroup_cs(parent); + mutex_lock(&callback_mutex); cs->mems_allowed = parent_cs->mems_allowed; cpumask_copy(cs->cpus_allowed, parent_cs->cpus_allowed); + mutex_unlock(&callback_mutex); return; } -- cgit v1.2.3-70-g09d2