The patch titled container freezer: prevent frozen tasks or cgroups from changing has been added to the -mm tree. Its filename is container-freezer-prevent-frozen-tasks-or-cgroups-from-changing.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://www.zip.com.au/~akpm/linux/patches/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: container freezer: prevent frozen tasks or cgroups from changing From: Matt Helsley <matthltc@xxxxxxxxxx> Don't let frozen tasks or cgroups change. This means frozen tasks can't leave their current cgroup for another cgroup. It also means that tasks cannot be added to or removed from a cgroup in the FROZEN state. We enforce these rules by checking for frozen tasks and cgroups in the can_attach() function. Signed-off-by: Matt Helsley <matthltc@xxxxxxxxxx> Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx> --- kernel/cgroup_freezer.c | 43 ++++++++++++++++++++++---------------- 1 file changed, 26 insertions(+), 17 deletions(-) diff -puN kernel/cgroup_freezer.c~container-freezer-prevent-frozen-tasks-or-cgroups-from-changing kernel/cgroup_freezer.c --- a/kernel/cgroup_freezer.c~container-freezer-prevent-frozen-tasks-or-cgroups-from-changing +++ a/kernel/cgroup_freezer.c @@ -145,22 +145,40 @@ static void freezer_destroy(struct cgrou kfree(cgroup_freezer(cgroup)); } +/* Task is frozen or will freeze immediately when next it gets woken */ +static bool is_task_frozen_enough(struct task_struct *task) +{ + return frozen(task) || + (task_is_stopped_or_traced(task) && freezing(task)); +} +/* + * The call to cgroup_lock() in the freezer.state write method prevents + * a write to that file racing against an attach, and hence the + * can_attach() result will remain valid until the attach completes. + */ static int freezer_can_attach(struct cgroup_subsys *ss, struct cgroup *new_cgroup, struct task_struct *task) { struct freezer *freezer; - int retval = 0; + int retval; + + /* Anything frozen can't move or be moved to/from */ + + if (is_task_frozen_enough(task)) + return -EBUSY; - /* - * The call to cgroup_lock() in the freezer.state write method prevents - * a write to that file racing against an attach, and hence the - * can_attach() result will remain valid until the attach completes. - */ freezer = cgroup_freezer(new_cgroup); if (freezer->state == STATE_FROZEN) + return -EBUSY; + + retval = 0; + task_lock(task); + freezer = task_freezer(task); + if (freezer->state == STATE_FROZEN) retval = -EBUSY; + task_unlock(task); return retval; } @@ -193,12 +211,7 @@ static void check_if_frozen(struct cgrou cgroup_iter_start(cgroup, &it); while ((task = cgroup_iter_next(cgroup, &it))) { ntotal++; - /* - * Task is frozen or will freeze immediately when next it gets - * woken - */ - if (frozen(task) || - (task_is_stopped_or_traced(task) && freezing(task))) + if (is_task_frozen_enough(task)) nfrozen++; } @@ -249,11 +262,7 @@ static int try_to_freeze_cgroup(struct c while ((task = cgroup_iter_next(cgroup, &it))) { if (!freeze_task(task, true)) continue; - if (task_is_stopped_or_traced(task) && freezing(task)) - /* - * The freeze flag is set so these tasks will - * immediately go into the fridge upon waking. - */ + if (is_task_frozen_enough(task)) continue; if (!freezing(task) && !freezer_should_skip(task)) num_cant_freeze_now++; _ Patches currently in -mm which might be from matthltc@xxxxxxxxxx are container-freezer-add-tif_freeze-flag-to-all-architectures.patch container-freezer-make-refrigerator-always-available.patch container-freezer-implement-freezer-cgroup-subsystem.patch container-freezer-implement-freezer-cgroup-subsystem-checkpatch-fixes.patch container-freezer-skip-frozen-cgroups-during-power-management-resume.patch container-freezer-prevent-frozen-tasks-or-cgroups-from-changing.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