From afcf6c8b75444382e0f9996157207ebae34a8848 Mon Sep 17 00:00:00 2001 From: Tejun Heo Date: Thu, 15 Oct 2015 16:41:53 -0400 Subject: [PATCH] cgroup: add cgroup_subsys->free() method and use it to fix pids controller pids controller is completely broken in that it uncharges when a task exits allowing zombies to escape resource control. With the recent updates, cgroup core now maintains cgroup association till task free and pids controller can be fixed by uncharging on free instead of exit. This patch adds cgroup_subsys->free() method and update pids controller to use it instead of ->exit() for uncharging. Signed-off-by: Tejun Heo Cc: Aleksa Sarai --- Documentation/cgroups/cgroups.txt | 4 ++++ include/linux/cgroup-defs.h | 1 + kernel/cgroup.c | 7 +++++++ kernel/cgroup_pids.c | 4 ++-- 4 files changed, 14 insertions(+), 2 deletions(-) diff --git a/Documentation/cgroups/cgroups.txt b/Documentation/cgroups/cgroups.txt index f935fac1e73b..c6256ae9885b 100644 --- a/Documentation/cgroups/cgroups.txt +++ b/Documentation/cgroups/cgroups.txt @@ -637,6 +637,10 @@ void exit(struct task_struct *task) Called during task exit. +void free(struct task_struct *task) + +Called when the task_struct is freed. + void bind(struct cgroup *root) (cgroup_mutex held by caller) diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h index 6a1ab64ee5f9..60d44b26276d 100644 --- a/include/linux/cgroup-defs.h +++ b/include/linux/cgroup-defs.h @@ -436,6 +436,7 @@ struct cgroup_subsys { void (*cancel_fork)(struct task_struct *task, void *priv); void (*fork)(struct task_struct *task, void *priv); void (*exit)(struct task_struct *task); + void (*free)(struct task_struct *task); void (*bind)(struct cgroup_subsys_state *root_css); int early_init; diff --git a/kernel/cgroup.c b/kernel/cgroup.c index 918658497625..867384369669 100644 --- a/kernel/cgroup.c +++ b/kernel/cgroup.c @@ -206,6 +206,7 @@ static u64 css_serial_nr_next = 1; */ static unsigned long have_fork_callback __read_mostly; static unsigned long have_exit_callback __read_mostly; +static unsigned long have_free_callback __read_mostly; /* Ditto for the can_fork callback. */ static unsigned long have_canfork_callback __read_mostly; @@ -5180,6 +5181,7 @@ static void __init cgroup_init_subsys(struct cgroup_subsys *ss, bool early) have_fork_callback |= (bool)ss->fork << ss->id; have_exit_callback |= (bool)ss->exit << ss->id; + have_free_callback |= (bool)ss->free << ss->id; have_canfork_callback |= (bool)ss->can_fork << ss->id; /* At system boot, before all subsystems have been @@ -5637,6 +5639,11 @@ void cgroup_exit(struct task_struct *tsk) void cgroup_free(struct task_struct *task) { struct css_set *cset = task_css_set(task); + struct cgroup_subsys *ss; + int ssid; + + for_each_subsys_which(ss, ssid, &have_free_callback) + ss->free(task); put_css_set(cset); } diff --git a/kernel/cgroup_pids.c b/kernel/cgroup_pids.c index 45f0856a61fe..cdd8df4e991c 100644 --- a/kernel/cgroup_pids.c +++ b/kernel/cgroup_pids.c @@ -266,7 +266,7 @@ static void pids_fork(struct task_struct *task, void *priv) css_put(old_css); } -static void pids_exit(struct task_struct *task) +static void pids_free(struct task_struct *task) { struct pids_cgroup *pids = css_pids(task_css(task, pids_cgrp_id)); @@ -347,7 +347,7 @@ struct cgroup_subsys pids_cgrp_subsys = { .can_fork = pids_can_fork, .cancel_fork = pids_cancel_fork, .fork = pids_fork, - .exit = pids_exit, + .free = pids_free, .legacy_cftypes = pids_files, .dfl_cftypes = pids_files, }; -- GitLab