Hello, This patchset updates cgroup_freezer so that * Unfreezable kernel tasks don't prevent a cgroup from transitioning into FROZEN from FREEZING. There's nothing userland can do with or about such tasks. * Tasks can be moved in and out of a frozen cgroup. Tasks are made to conform to the state of the new cgroup during migration. This behavior makes a lot more sense and removes the use of ->can_attach() which makes co-mounting difficult. * Remove use of cgroup_lock_live_group(). Grabbing cgroup_lock from outside cgroup proper creates a painful locking dependency and is being phased out. With the above behavior change, removing dependency on cgroup_lock is pretty easy. IMHO, it was simply the wrong behavior to implement which forced the wrong implementation. This patchset contains the following seven patches. 0001-cgroup-cgroup_subsys-fork-should-be-called-after-the.patch 0002-freezer-add-missing-mb-s-to-freezer_count-and-freeze.patch 0003-cgroup_freezer-make-it-official-that-writes-to-freez.patch 0004-cgroup_freezer-don-t-stall-transition-to-FROZEN-for-.patch 0005-cgroup_freezer-allow-moving-tasks-in-and-out-of-a-fr.patch 0006-cgroup_freezer-prepare-update_if_frozen-for-locking-.patch 0007-cgroup_freezer-don-t-use-cgroup_lock_live_group.patch 0001 is a fix for a rather embarrassing bug in cgroup core. It does things in the wrong order leaving a window for racing during fork. 0002 adds a missing mb() around freezing condition updates / checks. 0003-0004 make cgroup_freezer ignore unfreezable kernel tasks and handle PF_FREEZER_SKIP correctly. 0005 allows migrating tasks in and out of a frozen cgroup. 0006-0007 remove the use of cgroup_lock_live_group(). This patchset is on top of v3.7-rc1 and available in the following git branch. git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup.git review-cgroup_freezer-locking include/linux/cgroup.h | 1 include/linux/freezer.h | 50 +++++++++-- kernel/cgroup.c | 62 ++++++-------- kernel/cgroup_freezer.c | 210 ++++++++++++++++-------------------------------- kernel/fork.c | 9 -- 5 files changed, 147 insertions(+), 185 deletions(-) Thanks. -- tejun _______________________________________________ Containers mailing list Containers@xxxxxxxxxxxxxxxxxxxxxxxxxx https://lists.linuxfoundation.org/mailman/listinfo/containers
