The patch titled cpusets: set task's cpu_allowed to cpu_possible_map when attaching it into top cpuset has been added to the -mm tree. Its filename is cpusets-set-tasks-cpu_allowed-to-cpu_possible_map-when-attaching-it-into-top-cpuset.patch Before you just go and hit "reply", please: a) Consider who else should be cc'ed b) Prefer to cc a suitable mailing list as well c) Ideally: find the original patch on the mailing list and do a reply-to-all to that, adding suitable additional cc's *** Remember to use Documentation/SubmitChecklist when testing your code *** See http://userweb.kernel.org/~akpm/stuff/added-to-mm.txt to find out what to do about this The current -mm tree may be found at http://userweb.kernel.org/~akpm/mmotm/ ------------------------------------------------------ Subject: cpusets: set task's cpu_allowed to cpu_possible_map when attaching it into top cpuset From: Miao Xie <miaox@xxxxxxxxxxxxxx> I found a bug on my dual-cpu box. I created a sub cpuset in top cpuset and assign 1 to its cpus. And then we attach some tasks into this sub cpuset. After this, we offline CPU1. Now, the tasks in this new cpuset are moved into top cpuset automatically because there is no cpu in sub cpuset. Then we online CPU1, we find all the tasks which doesn't belong to top cpuset originally just run on CPU0. We fix this bug by setting task's cpu_allowed to cpu_possible_map when attaching it into top cpuset. This method needn't modify the current behavior of cpusets on CPU hotplug, and all of tasks in top cpuset use cpu_possible_map to initialize their cpu_allowed. Signed-off-by: Miao Xie <miaox@xxxxxxxxxxxxxx> Cc: Paul Menage <menage@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/cpuset.c | 10 +++++++--- 1 file changed, 7 insertions(+), 3 deletions(-) diff -puN kernel/cpuset.c~cpusets-set-tasks-cpu_allowed-to-cpu_possible_map-when-attaching-it-into-top-cpuset kernel/cpuset.c --- a/kernel/cpuset.c~cpusets-set-tasks-cpu_allowed-to-cpu_possible_map-when-attaching-it-into-top-cpuset +++ a/kernel/cpuset.c @@ -1338,10 +1338,14 @@ static void cpuset_attach(struct cgroup_ struct cpuset *oldcs = cgroup_cs(oldcont); int err; - mutex_lock(&callback_mutex); - guarantee_online_cpus(cs, &cpus); + if (cs == &top_cpuset) { + cpus = cpu_possible_map; + } else { + mutex_lock(&callback_mutex); + guarantee_online_cpus(cs, &cpus); + mutex_unlock(&callback_mutex); + } err = set_cpus_allowed_ptr(tsk, &cpus); - mutex_unlock(&callback_mutex); if (err) return; _ Patches currently in -mm which might be from miaox@xxxxxxxxxxxxxx are cpusets-set-tasks-cpu_allowed-to-cpu_possible_map-when-attaching-it-into-top-cpuset.patch -- To unsubscribe from this list: send the line "unsubscribe mm-commits" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html