From 3c426d5e114035d00453bb5d82a92826db1ed71f Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Tue, 16 Oct 2012 15:03:14 -0700 Subject: [PATCH] cgroup_freezer: don't stall transition to FROZEN for PF_NOFREEZE or PF_FREEZER_SKIP tasks cgroup_freezer doesn't transition from FREEZING to FROZEN if the cgroup contains PF_NOFREEZE tasks or tasks sleeping with PF_FREEZER_SKIP set. Only kernel tasks can be non-freezable (PF_NOFREEZE) and there's nothing cgroup_freezer or userland can do about or to it. It's pointless to stall the transition for PF_NOFREEZE tasks. PF_FREEZER_SKIP indicates that the task can be skipped when determining whether frozen state is reached. A task with PF_FREEZER_SKIP is guaranteed to perform try_to_freeze() after it wakes up and can be considered frozen much like stopped or traced tasks. Note that a vfork parent uses PF_FREEZER_SKIP while waiting for the child. This updates update_if_frozen() such that it only considers freezable tasks and treats %true freezer_should_skip() tasks as frozen. This allows cgroups w/ kthreads and vfork parents successfully reach FROZEN state. Signed-off-by: Tejun Heo Cc: Oleg Nesterov Cc: Rafael J. Wysocki --- Reading git-format-patch failed