| Date | Tue, 30 Mar 2010 15:56:08 -0700 | From | Greg KH <> | Subject | [090/116] cpuset: fix the problem that cpuset_mem_spread_node() returns an offline node |
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2.6.32-stable review patch. If anyone has any objections, please let us know.
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From: Miao Xie <miaox@cn.fujitsu.com>
commit 5ab116c9349ef52d6fbd2e2917a53f13194b048e upstream.
cpuset_mem_spread_node() returns an offline node, and causes an oops.
This patch fixes it by initializing task->mems_allowed to node_states[N_HIGH_MEMORY], and updating task->mems_allowed when doing memory hotplug.
Signed-off-by: Miao Xie <miaox@cn.fujitsu.com> Acked-by: David Rientjes <rientjes@google.com> Reported-by: Nick Piggin <npiggin@suse.de> Tested-by: Nick Piggin <npiggin@suse.de> Cc: Paul Menage <menage@google.com> Cc: Li Zefan <lizf@cn.fujitsu.com> Cc: Ingo Molnar <mingo@elte.hu> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org> Signed-off-by: Greg Kroah-Hartman <gregkh@suse.de>
--- init/main.c | 2 +- kernel/cpuset.c | 20 ++++++++++++-------- kernel/kthread.c | 2 +- 3 files changed, 14 insertions(+), 10 deletions(-)
--- a/init/main.c +++ b/init/main.c @@ -846,7 +846,7 @@ static int __init kernel_init(void * unu /* * init can allocate pages on any node */ - set_mems_allowed(node_possible_map); + set_mems_allowed(node_states[N_HIGH_MEMORY]); /* * init can run on any cpu. */ --- a/kernel/cpuset.c +++ b/kernel/cpuset.c @@ -921,9 +921,6 @@ static int update_cpumask(struct cpuset * call to guarantee_online_mems(), as we know no one is changing * our task's cpuset. * - * Hold callback_mutex around the two modifications of our tasks - * mems_allowed to synchronize with cpuset_mems_allowed(). - * * While the mm_struct we are migrating is typically from some * other task, the task_struct mems_allowed that we are hacking * is for our current task, which must allocate new pages for that @@ -1392,11 +1389,10 @@ static void cpuset_attach(struct cgroup_ if (cs == &top_cpuset) { cpumask_copy(cpus_attach, cpu_possible_mask); - to = node_possible_map; } 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); @@ -2091,15 +2087,23 @@ static int cpuset_track_online_cpus(stru static int cpuset_track_online_nodes(struct notifier_block *self, unsigned long action, void *arg) { + nodemask_t oldmems; + cgroup_lock(); switch (action) { case MEM_ONLINE: - case MEM_OFFLINE: + oldmems = top_cpuset.mems_allowed; mutex_lock(&callback_mutex); top_cpuset.mems_allowed = node_states[N_HIGH_MEMORY]; mutex_unlock(&callback_mutex); - if (action == MEM_OFFLINE) - scan_for_empty_cpusets(&top_cpuset); + update_tasks_nodemask(&top_cpuset, &oldmems, NULL); + break; + case MEM_OFFLINE: + /* + * needn't update top_cpuset.mems_allowed explicitly because + * scan_for_empty_cpusets() will update it. + */ + scan_for_empty_cpusets(&top_cpuset); break; default: break; --- a/kernel/kthread.c +++ b/kernel/kthread.c @@ -196,7 +196,7 @@ int kthreadd(void *unused) set_task_comm(tsk, "kthreadd"); ignore_signals(tsk); set_cpus_allowed_ptr(tsk, cpu_all_mask); - set_mems_allowed(node_possible_map); + set_mems_allowed(node_states[N_HIGH_MEMORY]); current->flags |= PF_NOFREEZE | PF_FREEZER_NOSIG;
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