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authorLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 17:22:14 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2021-07-01 17:22:14 -0700
commit3dbdb38e286903ec220aaf1fb29a8d94297da246 (patch)
treef80cd38836298d6bb465462e30f4dd644b018735
parente267992f9ef0bf717d70a9ee18049782f77e4b3a (diff)
parent3958e2d0c34e18c41b60dc01832bd670a59ef70f (diff)
downloadlinux-3dbdb38e286903ec220aaf1fb29a8d94297da246.tar.bz2
Merge branch 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup
Pull cgroup updates from Tejun Heo: - cgroup.kill is added which implements atomic killing of the whole subtree. Down the line, this should be able to replace the multiple userland implementations of "keep killing till empty". - PSI can now be turned off at boot time to avoid overhead for configurations which don't care about PSI. * 'for-5.14' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup: cgroup: make per-cgroup pressure stall tracking configurable cgroup: Fix kernel-doc cgroup: inline cgroup_task_freeze() tests/cgroup: test cgroup.kill tests/cgroup: move cg_wait_for(), cg_prepare_for_wait() tests/cgroup: use cgroup.kill in cg_killall() docs/cgroup: add entry for cgroup.kill cgroup: introduce cgroup.kill
-rw-r--r--Documentation/admin-guide/cgroup-v2.rst15
-rw-r--r--Documentation/admin-guide/kernel-parameters.txt9
-rw-r--r--include/linux/cgroup-defs.h4
-rw-r--r--include/linux/cgroup.h25
-rw-r--r--kernel/cgroup/cgroup.c180
-rw-r--r--kernel/cgroup/rstat.c2
-rw-r--r--kernel/sched/psi.c30
-rw-r--r--tools/testing/selftests/cgroup/.gitignore3
-rw-r--r--tools/testing/selftests/cgroup/Makefile2
-rw-r--r--tools/testing/selftests/cgroup/cgroup_util.c51
-rw-r--r--tools/testing/selftests/cgroup/cgroup_util.h2
-rw-r--r--tools/testing/selftests/cgroup/test_freezer.c57
-rw-r--r--tools/testing/selftests/cgroup/test_kill.c297
13 files changed, 569 insertions, 108 deletions
diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
index 4e59925e6583..5c7377b5bd3e 100644
--- a/Documentation/admin-guide/cgroup-v2.rst
+++ b/Documentation/admin-guide/cgroup-v2.rst
@@ -953,6 +953,21 @@ All cgroup core files are prefixed with "cgroup."
it's possible to delete a frozen (and empty) cgroup, as well as
create new sub-cgroups.
+ cgroup.kill
+ A write-only single value file which exists in non-root cgroups.
+ The only allowed value is "1".
+
+ Writing "1" to the file causes the cgroup and all descendant cgroups to
+ be killed. This means that all processes located in the affected cgroup
+ tree will be killed via SIGKILL.
+
+ Killing a cgroup tree will deal with concurrent forks appropriately and
+ is protected against migrations.
+
+ In a threaded cgroup, writing this file fails with EOPNOTSUPP as
+ killing cgroups is a process directed operation, i.e. it affects
+ the whole thread-group.
+
Controllers
===========
diff --git a/Documentation/admin-guide/kernel-parameters.txt b/Documentation/admin-guide/kernel-parameters.txt
index 2991f6e692bd..0315407f5f57 100644
--- a/Documentation/admin-guide/kernel-parameters.txt
+++ b/Documentation/admin-guide/kernel-parameters.txt
@@ -497,16 +497,21 @@
ccw_timeout_log [S390]
See Documentation/s390/common_io.rst for details.
- cgroup_disable= [KNL] Disable a particular controller
- Format: {name of the controller(s) to disable}
+ cgroup_disable= [KNL] Disable a particular controller or optional feature
+ Format: {name of the controller(s) or feature(s) to disable}
The effects of cgroup_disable=foo are:
- foo isn't auto-mounted if you mount all cgroups in
a single hierarchy
- foo isn't visible as an individually mountable
subsystem
+ - if foo is an optional feature then the feature is
+ disabled and corresponding cgroup files are not
+ created
{Currently only "memory" controller deal with this and
cut the overhead, others just disable the usage. So
only cgroup_disable=memory is actually worthy}
+ Specifying "pressure" disables per-cgroup pressure
+ stall information accounting feature
cgroup_no_v1= [KNL] Disable cgroup controllers and named hierarchies in v1
Format: { { controller | "all" | "named" }
diff --git a/include/linux/cgroup-defs.h b/include/linux/cgroup-defs.h
index fb8f6d2cd104..e1c705fdfa7c 100644
--- a/include/linux/cgroup-defs.h
+++ b/include/linux/cgroup-defs.h
@@ -71,6 +71,9 @@ enum {
/* Cgroup is frozen. */
CGRP_FROZEN,
+
+ /* Control group has to be killed. */
+ CGRP_KILL,
};
/* cgroup_root->flags */
@@ -110,6 +113,7 @@ enum {
CFTYPE_NO_PREFIX = (1 << 3), /* (DON'T USE FOR NEW FILES) no subsys prefix */
CFTYPE_WORLD_WRITABLE = (1 << 4), /* (DON'T USE FOR NEW FILES) S_IWUGO */
CFTYPE_DEBUG = (1 << 5), /* create when cgroup_debug */
+ CFTYPE_PRESSURE = (1 << 6), /* only if pressure feature is enabled */
/* internal flags, do not use outside cgroup core proper */
__CFTYPE_ONLY_ON_DFL = (1 << 16), /* only on default hierarchy */
diff --git a/include/linux/cgroup.h b/include/linux/cgroup.h
index 6bc9c76680b2..2cc237e3e8b3 100644
--- a/include/linux/cgroup.h
+++ b/include/linux/cgroup.h
@@ -676,6 +676,8 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
return &cgrp->psi;
}
+bool cgroup_psi_enabled(void);
+
static inline void cgroup_init_kthreadd(void)
{
/*
@@ -735,6 +737,11 @@ static inline struct psi_group *cgroup_psi(struct cgroup *cgrp)
return NULL;
}
+static inline bool cgroup_psi_enabled(void)
+{
+ return false;
+}
+
static inline bool task_under_cgroup_hierarchy(struct task_struct *task,
struct cgroup *ancestor)
{
@@ -906,20 +913,6 @@ void cgroup_freeze(struct cgroup *cgrp, bool freeze);
void cgroup_freezer_migrate_task(struct task_struct *task, struct cgroup *src,
struct cgroup *dst);
-static inline bool cgroup_task_freeze(struct task_struct *task)
-{
- bool ret;
-
- if (task->flags & PF_KTHREAD)
- return false;
-
- rcu_read_lock();
- ret = test_bit(CGRP_FREEZE, &task_dfl_cgroup(task)->flags);
- rcu_read_unlock();
-
- return ret;
-}
-
static inline bool cgroup_task_frozen(struct task_struct *task)
{
return task->frozen;
@@ -929,10 +922,6 @@ static inline bool cgroup_task_frozen(struct task_struct *task)
static inline void cgroup_enter_frozen(void) { }
static inline void cgroup_leave_frozen(bool always_leave) { }
-static inline bool cgroup_task_freeze(struct task_struct *task)
-{
- return false;
-}
static inline bool cgroup_task_frozen(struct task_struct *task)
{
return false;
diff --git a/kernel/cgroup/cgroup.c b/kernel/cgroup/cgroup.c
index 9cc8c3a686b1..ea5b0f01d2b3 100644
--- a/kernel/cgroup/cgroup.c
+++ b/kernel/cgroup/cgroup.c
@@ -209,6 +209,22 @@ struct cgroup_namespace init_cgroup_ns = {
static struct file_system_type cgroup2_fs_type;
static struct cftype cgroup_base_files[];
+/* cgroup optional features */
+enum cgroup_opt_features {
+#ifdef CONFIG_PSI
+ OPT_FEATURE_PRESSURE,
+#endif
+ OPT_FEATURE_COUNT
+};
+
+static const char *cgroup_opt_feature_names[OPT_FEATURE_COUNT] = {
+#ifdef CONFIG_PSI
+ "pressure",
+#endif
+};
+
+static u16 cgroup_feature_disable_mask __read_mostly;
+
static int cgroup_apply_control(struct cgroup *cgrp);
static void cgroup_finalize_control(struct cgroup *cgrp, int ret);
static void css_task_iter_skip(struct css_task_iter *it,
@@ -2390,7 +2406,7 @@ struct task_struct *cgroup_taskset_next(struct cgroup_taskset *tset,
}
/**
- * cgroup_taskset_migrate - migrate a taskset
+ * cgroup_migrate_execute - migrate a taskset
* @mgctx: migration context
*
* Migrate tasks in @mgctx as setup by migration preparation functions.
@@ -3632,6 +3648,18 @@ static void cgroup_pressure_release(struct kernfs_open_file *of)
{
psi_trigger_replace(&of->priv, NULL);
}
+
+bool cgroup_psi_enabled(void)
+{
+ return (cgroup_feature_disable_mask & (1 << OPT_FEATURE_PRESSURE)) == 0;
+}
+
+#else /* CONFIG_PSI */
+bool cgroup_psi_enabled(void)
+{
+ return false;
+}
+
#endif /* CONFIG_PSI */
static int cgroup_freeze_show(struct seq_file *seq, void *v)
@@ -3668,6 +3696,80 @@ static ssize_t cgroup_freeze_write(struct kernfs_open_file *of,
return nbytes;
}
+static void __cgroup_kill(struct cgroup *cgrp)
+{
+ struct css_task_iter it;
+ struct task_struct *task;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ spin_lock_irq(&css_set_lock);
+ set_bit(CGRP_KILL, &cgrp->flags);
+ spin_unlock_irq(&css_set_lock);
+
+ css_task_iter_start(&cgrp->self, CSS_TASK_ITER_PROCS | CSS_TASK_ITER_THREADED, &it);
+ while ((task = css_task_iter_next(&it))) {
+ /* Ignore kernel threads here. */
+ if (task->flags & PF_KTHREAD)
+ continue;
+
+ /* Skip tasks that are already dying. */
+ if (__fatal_signal_pending(task))
+ continue;
+
+ send_sig(SIGKILL, task, 0);
+ }
+ css_task_iter_end(&it);
+
+ spin_lock_irq(&css_set_lock);
+ clear_bit(CGRP_KILL, &cgrp->flags);
+ spin_unlock_irq(&css_set_lock);
+}
+
+static void cgroup_kill(struct cgroup *cgrp)
+{
+ struct cgroup_subsys_state *css;
+ struct cgroup *dsct;
+
+ lockdep_assert_held(&cgroup_mutex);
+
+ cgroup_for_each_live_descendant_pre(dsct, css, cgrp)
+ __cgroup_kill(dsct);
+}
+
+static ssize_t cgroup_kill_write(struct kernfs_open_file *of, char *buf,
+ size_t nbytes, loff_t off)
+{
+ ssize_t ret = 0;
+ int kill;
+ struct cgroup *cgrp;
+
+ ret = kstrtoint(strstrip(buf), 0, &kill);
+ if (ret)
+ return ret;
+
+ if (kill != 1)
+ return -ERANGE;
+
+ cgrp = cgroup_kn_lock_live(of->kn, false);
+ if (!cgrp)
+ return -ENOENT;
+
+ /*
+ * Killing is a process directed operation, i.e. the whole thread-group
+ * is taken down so act like we do for cgroup.procs and only make this
+ * writable in non-threaded cgroups.
+ */
+ if (cgroup_is_threaded(cgrp))
+ ret = -EOPNOTSUPP;
+ else
+ cgroup_kill(cgrp);
+
+ cgroup_kn_unlock(of->kn);
+
+ return ret ?: nbytes;
+}
+
static int cgroup_file_open(struct kernfs_open_file *of)
{
struct cftype *cft = of_cft(of);
@@ -3882,6 +3984,8 @@ static int cgroup_addrm_files(struct cgroup_subsys_state *css,
restart:
for (cft = cfts; cft != cft_end && cft->name[0] != '\0'; cft++) {
/* does cft->flags tell us to skip this file on @cgrp? */
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
if ((cft->flags & __CFTYPE_ONLY_ON_DFL) && !cgroup_on_dfl(cgrp))
continue;
if ((cft->flags & __CFTYPE_NOT_ON_DFL) && cgroup_on_dfl(cgrp))
@@ -3959,6 +4063,9 @@ static int cgroup_init_cftypes(struct cgroup_subsys *ss, struct cftype *cfts)
WARN_ON(cft->ss || cft->kf_ops);
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
+
if (cft->seq_start)
kf_ops = &cgroup_kf_ops;
else
@@ -4861,12 +4968,18 @@ static struct cftype cgroup_base_files[] = {
.write = cgroup_freeze_write,
},
{
+ .name = "cgroup.kill",
+ .flags = CFTYPE_NOT_ON_ROOT,
+ .write = cgroup_kill_write,
+ },
+ {
.name = "cpu.stat",
.seq_show = cpu_stat_show,
},
#ifdef CONFIG_PSI
{
.name = "io.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_io_pressure_show,
.write = cgroup_io_pressure_write,
.poll = cgroup_pressure_poll,
@@ -4874,6 +4987,7 @@ static struct cftype cgroup_base_files[] = {
},
{
.name = "memory.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_memory_pressure_show,
.write = cgroup_memory_pressure_write,
.poll = cgroup_pressure_poll,
@@ -4881,6 +4995,7 @@ static struct cftype cgroup_base_files[] = {
},
{
.name = "cpu.pressure",
+ .flags = CFTYPE_PRESSURE,
.seq_show = cgroup_cpu_pressure_show,
.write = cgroup_cpu_pressure_write,
.poll = cgroup_pressure_poll,
@@ -6080,6 +6195,8 @@ void cgroup_post_fork(struct task_struct *child,
struct kernel_clone_args *kargs)
__releases(&cgroup_threadgroup_rwsem) __releases(&cgroup_mutex)
{
+ unsigned long cgrp_flags = 0;
+ bool kill = false;
struct cgroup_subsys *ss;
struct css_set *cset;
int i;
@@ -6091,6 +6208,11 @@ void cgroup_post_fork(struct task_struct *child,
/* init tasks are special, only link regular threads */
if (likely(child->pid)) {
+ if (kargs->cgrp)
+ cgrp_flags = kargs->cgrp->flags;
+ else
+ cgrp_flags = cset->dfl_cgrp->flags;
+
WARN_ON_ONCE(!list_empty(&child->cg_list));
cset->nr_tasks++;
css_set_move_task(child, NULL, cset, false);
@@ -6099,23 +6221,32 @@ void cgroup_post_fork(struct task_struct *child,
cset = NULL;
}
- /*
- * If the cgroup has to be frozen, the new task has too. Let's set
- * the JOBCTL_TRAP_FREEZE jobctl bit to get the task into the
- * frozen state.
- */
- if (unlikely(cgroup_task_freeze(child))) {
- spin_lock(&child->sighand->siglock);
- WARN_ON_ONCE(child->frozen);
- child->jobctl |= JOBCTL_TRAP_FREEZE;
- spin_unlock(&child->sighand->siglock);
+ if (!(child->flags & PF_KTHREAD)) {
+ if (unlikely(test_bit(CGRP_FREEZE, &cgrp_flags))) {
+ /*
+ * If the cgroup has to be frozen, the new task has
+ * too. Let's set the JOBCTL_TRAP_FREEZE jobctl bit to
+ * get the task into the frozen state.
+ */
+ spin_lock(&child->sighand->siglock);
+ WARN_ON_ONCE(child->frozen);
+ child->jobctl |= JOBCTL_TRAP_FREEZE;
+ spin_unlock(&child->sighand->siglock);
+
+ /*
+ * Calling cgroup_update_frozen() isn't required here,
+ * because it will be called anyway a bit later from
+ * do_freezer_trap(). So we avoid cgroup's transient
+ * switch from the frozen state and back.
+ */
+ }
/*
- * Calling cgroup_update_frozen() isn't required here,
- * because it will be called anyway a bit later from
- * do_freezer_trap(). So we avoid cgroup's transient switch
- * from the frozen state and back.
+ * If the cgroup is to be killed notice it now and take the
+ * child down right after we finished preparing it for
+ * userspace.
*/
+ kill = test_bit(CGRP_KILL, &cgrp_flags);
}
spin_unlock_irq(&css_set_lock);
@@ -6138,6 +6269,10 @@ void cgroup_post_fork(struct task_struct *child,
put_css_set(rcset);
}
+ /* Cgroup has to be killed so take down child immediately. */
+ if (unlikely(kill))
+ do_send_sig_info(SIGKILL, SEND_SIG_NOINFO, child, PIDTYPE_TGID);
+
cgroup_css_set_put_fork(kargs);
}
@@ -6163,7 +6298,8 @@ void cgroup_exit(struct task_struct *tsk)
cset->nr_tasks--;
WARN_ON_ONCE(cgroup_task_frozen(tsk));
- if (unlikely(cgroup_task_freeze(tsk)))
+ if (unlikely(!(tsk->flags & PF_KTHREAD) &&
+ test_bit(CGRP_FREEZE, &task_dfl_cgroup(tsk)->flags)))
cgroup_update_frozen(task_dfl_cgroup(tsk));
spin_unlock_irq(&css_set_lock);
@@ -6214,6 +6350,15 @@ static int __init cgroup_disable(char *str)
pr_info("Disabling %s control group subsystem\n",
ss->name);
}
+
+ for (i = 0; i < OPT_FEATURE_COUNT; i++) {
+ if (strcmp(token, cgroup_opt_feature_names[i]))
+ continue;
+ cgroup_feature_disable_mask |= 1 << i;
+ pr_info("Disabling %s control group feature\n",
+ cgroup_opt_feature_names[i]);
+ break;
+ }
}
return 1;
}
@@ -6512,6 +6657,9 @@ static ssize_t show_delegatable_files(struct cftype *files, char *buf,
if (!(cft->flags & CFTYPE_NS_DELEGATABLE))
continue;
+ if ((cft->flags & CFTYPE_PRESSURE) && !cgroup_psi_enabled())
+ continue;
+
if (prefix)
ret += snprintf(buf + ret, size - ret, "%s.", prefix);
diff --git a/kernel/cgroup/rstat.c b/kernel/cgroup/rstat.c
index cee265cb535c..7f0e58917432 100644
--- a/kernel/cgroup/rstat.c
+++ b/kernel/cgroup/rstat.c
@@ -220,7 +220,7 @@ void cgroup_rstat_flush_irqsafe(struct cgroup *cgrp)
}
/**
- * cgroup_rstat_flush_begin - flush stats in @cgrp's subtree and hold
+ * cgroup_rstat_flush_hold - flush stats in @cgrp's subtree and hold
* @cgrp: target cgroup
*
* Flush stats in @cgrp's subtree and prevent further flushes. Must be
diff --git a/kernel/sched/psi.c b/kernel/sched/psi.c
index 58b36d17a09a..1652f2bb54b7 100644
--- a/kernel/sched/psi.c
+++ b/kernel/sched/psi.c
@@ -148,6 +148,7 @@
static int psi_bug __read_mostly;
DEFINE_STATIC_KEY_FALSE(psi_disabled);
+DEFINE_STATIC_KEY_TRUE(psi_cgroups_enabled);
#ifdef CONFIG_PSI_DEFAULT_DISABLED
static bool psi_enable;
@@ -215,6 +216,9 @@ void __init psi_init(void)
return;
}
+ if (!cgroup_psi_enabled())
+ static_branch_disable(&psi_cgroups_enabled);
+
psi_period = jiffies_to_nsecs(PSI_FREQ);
group_init(&psi_system);
}
@@ -748,23 +752,23 @@ static void psi_group_change(struct psi_group *group, int cpu,
static struct psi_group *iterate_groups(struct task_struct *task, void **iter)
{
+ if (*iter == &psi_system)
+ return NULL;
+
#ifdef CONFIG_CGROUPS
- struct cgroup *cgroup = NULL;
+ if (static_branch_likely(&psi_cgroups_enabled)) {
+ struct cgroup *cgroup = NULL;
- if (!*iter)
- cgroup = task->cgroups->dfl_cgrp;
- else if (*iter == &psi_system)
- return NULL;
- else
- cgroup = cgroup_parent(*iter);
+ if (!*iter)
+ cgroup = task->cgroups->dfl_cgrp;
+ else
+ cgroup = cgroup_parent(*iter);
- if (cgroup && cgroup_parent(cgroup)) {
- *iter = cgroup;
- return cgroup_psi(cgroup);
+ if (cgroup && cgroup_parent(cgroup)) {
+ *iter = cgroup;
+ return cgroup_psi(cgroup);
+ }
}
-#else
- if (*iter)
- return NULL;
#endif
*iter = &psi_system;
return &psi_system;
diff --git a/tools/testing/selftests/cgroup/.gitignore b/tools/testing/selftests/cgroup/.gitignore
index 84cfcabea838..be9643ef6285 100644
--- a/tools/testing/selftests/cgroup/.gitignore
+++ b/tools/testing/selftests/cgroup/.gitignore
@@ -2,4 +2,5 @@
test_memcontrol
test_core
test_freezer
-test_kmem \ No newline at end of file
+test_kmem
+test_kill
diff --git a/tools/testing/selftests/cgroup/Makefile b/tools/testing/selftests/cgroup/Makefile
index f027d933595b..59e222460581 100644
--- a/tools/testing/selftests/cgroup/Makefile
+++ b/tools/testing/selftests/cgroup/Makefile
@@ -9,6 +9,7 @@ TEST_GEN_PROGS = test_memcontrol
TEST_GEN_PROGS += test_kmem
TEST_GEN_PROGS += test_core
TEST_GEN_PROGS += test_freezer
+TEST_GEN_PROGS += test_kill
include ../lib.mk
@@ -16,3 +17,4 @@ $(OUTPUT)/test_memcontrol: cgroup_util.c ../clone3/clone3_selftests.h
$(OUTPUT)/test_kmem: cgroup_util.c ../clone3/clone3_selftests.h
$(OUTPUT)/test_core: cgroup_util.c ../clone3/clone3_selftests.h
$(OUTPUT)/test_freezer: cgroup_util.c ../clone3/clone3_selftests.h
+$(OUTPUT)/test_kill: cgroup_util.c ../clone3/clone3_selftests.h ../pidfd/pidfd.h
diff --git a/tools/testing/selftests/cgroup/cgroup_util.c b/tools/testing/selftests/cgroup/cgroup_util.c
index 027014662fb2..623cec04ad42 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.c
+++ b/tools/testing/selftests/cgroup/cgroup_util.c
@@ -5,10 +5,12 @@
#include <errno.h>
#include <fcntl.h>
#include <linux/limits.h>
+#include <poll.h>
#include <signal.h>
#include <stdio.h>
#include <stdlib.h>
#include <string.h>
+#include <sys/inotify.h>
#include <sys/stat.h>
#include <sys/types.h>
#include <sys/wait.h>
@@ -252,6 +254,10 @@ int cg_killall(const char *cgroup)
char buf[PAGE_SIZE];
char *ptr = buf;
+ /* If cgroup.kill exists use it. */
+ if (!cg_write(cgroup, "cgroup.kill", "1"))
+ return 0;
+
if (cg_read(cgroup, "cgroup.procs", buf, sizeof(buf)))
return -1;
@@ -576,3 +582,48 @@ int clone_into_cgroup_run_wait(const char *cgroup)
(void)clone_reap(pid, WEXITED);
return 0;
}
+
+int cg_prepare_for_wait(const char *cgroup)
+{
+ int fd, ret = -1;
+
+ fd = inotify_init1(0);
+ if (fd == -1)
+ return fd;
+
+ ret = inotify_add_watch(fd, cg_control(cgroup, "cgroup.events"),
+ IN_MODIFY);
+ if (ret == -1) {
+ close(fd);
+ fd = -1;
+ }
+
+ return fd;
+}
+
+int cg_wait_for(int fd)
+{
+ int ret = -1;
+ struct pollfd fds = {
+ .fd = fd,
+ .events = POLLIN,
+ };
+
+ while (true) {
+ ret = poll(&fds, 1, 10000);
+
+ if (ret == -1) {
+ if (errno == EINTR)
+ continue;
+
+ break;
+ }
+
+ if (ret > 0 && fds.revents & POLLIN) {
+ ret = 0;
+ break;
+ }
+ }
+
+ return ret;
+}
diff --git a/tools/testing/selftests/cgroup/cgroup_util.h b/tools/testing/selftests/cgroup/cgroup_util.h
index 5a1305dd1f0b..82e59cdf16e7 100644
--- a/tools/testing/selftests/cgroup/cgroup_util.h
+++ b/tools/testing/selftests/cgroup/cgroup_util.h
@@ -54,3 +54,5 @@ extern pid_t clone_into_cgroup(int cgroup_fd);
extern int clone_reap(pid_t pid, int options);
extern int clone_into_cgroup_run_wait(const char *cgroup);
extern int dirfd_open_opath(const char *dir);
+extern int cg_prepare_for_wait(const char *cgroup);
+extern int cg_wait_for(int fd);
diff --git a/tools/testing/selftests/cgroup/test_freezer.c b/tools/testing/selftests/cgroup/test_freezer.c
index 23d8fa4a3e4e..ff519029f6f4 100644
--- a/tools/testing/selftests/cgroup/test_freezer.c
+++ b/tools/testing/selftests/cgroup/test_freezer.c
@@ -7,9 +7,7 @@
#include <unistd.h>
#include <stdio.h>
#include <errno.h>
-#include <poll.h>
#include <stdlib.h>
-#include <sys/inotify.h>
#include <string.h>
#include <sys/wait.h>
@@ -55,61 +53,6 @@ static int cg_freeze_nowait(const char *cgroup, bool freeze)
}
/*
- * Prepare for waiting on cgroup.events file.
- */
-static int cg_prepare_for_wait(const char *cgroup)
-{
- int fd, ret = -1;
-
- fd = inotify_init1(0);
- if (fd == -1) {
- debug("Error: inotify_init1() failed\n");
- return fd;
- }
-
- ret = inotify_add_watch(fd, cg_control(cgroup, "cgroup.events"),
- IN_MODIFY);
- if (ret == -1) {
- debug("Error: inotify_add_watch() failed\n");
- close(fd);
- fd = -1;
- }
-
- return fd;
-}
-
-/*
- * Wait for an event. If there are no events for 10 seconds,
- * treat this an error.
- */
-static int cg_wait_for(int fd)
-{
- int ret = -1;
- struct pollfd fds = {
- .fd = fd,
- .events = POLLIN,
- };
-
- while (true) {
- ret = poll(&fds, 1, 10000);
-
- if (ret == -1) {
- if (errno == EINTR)
- continue;
- debug("Error: poll() failed\n");
- break;
- }
-
- if (ret > 0 && fds.revents & POLLIN) {
- ret = 0;
- break;
- }
- }
-
- return ret;
-}
-
-/*
* Attach a task to the given cgroup and wait for a cgroup frozen event.
* All transient events (e.g. populated) are ignored.
*/
diff --git a/tools/testing/selftests/cgroup/test_kill.c b/tools/testing/selftests/cgroup/test_kill.c
new file mode 100644
index 000000000000..6153690319c9
--- /dev/null
+++ b/tools/testing/selftests/cgroup/test_kill.c
@@ -0,0 +1,297 @@
+/* SPDX-License-Identifier: GPL-2.0 */
+
+#include <errno.h>
+#include <linux/limits.h>
+#include <stdbool.h>
+#include <stdio.h>
+#include <stdlib.h>
+#include <string.h>
+#include <sys/types.h>
+#include <unistd.h>
+
+#include "../kselftest.h"
+#include "../pidfd/pidfd.h"
+#include "cgroup_util.h"
+
+/*
+ * Kill the given cgroup and wait for the inotify signal.
+ * If there are no events in 10 seconds, treat this as an error.
+ * Then check that the cgroup is in the desired state.
+ */
+static int cg_kill_wait(const char *cgroup)
+{
+ int fd, ret = -1;
+
+ fd = cg_prepare_for_wait(cgroup);
+ if (fd < 0)
+ return fd;
+
+ ret = cg_write(cgroup, "cgroup.kill", "1");
+ if (ret)
+ goto out;
+
+ ret = cg_wait_for(fd);
+ if (ret)
+ goto out;
+
+out:
+ close(fd);
+ return ret;
+}
+
+/*
+ * A simple process running in a sleep loop until being
+ * re-parented.
+ */
+static int child_fn(const char *cgroup, void *arg)
+{
+ int ppid = getppid();
+
+ while (getppid() == ppid)
+ usleep(1000);
+
+ return getppid() == ppid;
+}
+
+static int test_cgkill_simple(const char *root)
+{
+ pid_t pids[100];
+ int ret = KSFT_FAIL;
+ char *cgroup = NULL;
+ int i;
+
+ cgroup = cg_name(root, "cg_test_simple");
+ if (!cgroup)
+ goto cleanup;
+
+ if (cg_create(cgroup))
+ goto cleanup;
+
+ for (i = 0; i < 100; i++)
+ pids[i] = cg_run_nowait(cgroup, child_fn, NULL);
+
+ if (cg_wait_for_proc_count(cgroup, 100))
+ goto cleanup;
+
+ if (cg_read_strcmp(cgroup, "cgroup.events", "populated 1\n"))
+ goto cleanup;
+
+ if (cg_kill_wait(cgroup))
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ for (i = 0; i < 100; i++)
+ wait_for_pid(pids[i]);
+
+ if (ret == KSFT_PASS &&
+ cg_read_strcmp(cgroup, "cgroup.events", "populated 0\n"))
+ ret = KSFT_FAIL;
+
+ if (cgroup)
+ cg_destroy(cgroup);
+ free(cgroup);
+ return ret;
+}
+
+/*
+ * The test creates the following hierarchy:
+ * A
+ * / / \ \
+ * B E I K
+ * /\ |
+ * C D F
+ * |
+ * G
+ * |
+ * H
+ *
+ * with a process in C, H and 3 processes in K.
+ * Then it tries to kill the whole tree.
+ */
+static int test_cgkill_tree(const char *root)
+{
+ pid_t pids[5];
+ char *cgroup[10] = {0};
+ int ret = KSFT_FAIL;
+ int i;
+
+ cgroup[0] = cg_name(root, "cg_test_tree_A");
+ if (!cgroup[0])
+ goto cleanup;
+
+ cgroup[1] = cg_name(cgroup[0], "B");
+ if (!cgroup[1])
+ goto cleanup;
+
+ cgroup[2] = cg_name(cgroup[1], "C");
+ if (!cgroup[2])
+ goto cleanup;
+
+ cgroup[3] = cg_name(cgroup[1], "D");
+ if (!cgroup[3])
+ goto cleanup;
+
+ cgroup[4] = cg_name(cgroup[0], "E");
+ if (!cgroup[4])
+ goto cleanup;
+
+ cgroup[5] = cg_name(cgroup[4], "F");
+ if (!cgroup[5])
+ goto cleanup;
+
+ cgroup[6] = cg_name(cgroup[5], "G");
+ if (!cgroup[6])
+ goto cleanup;
+
+ cgroup[7] = cg_name(cgroup[6], "H");
+ if (!cgroup[7])
+ goto cleanup;
+
+ cgroup[8] = cg_name(cgroup[0], "I");
+ if (!cgroup[8])
+ goto cleanup;
+
+ cgroup[9] = cg_name(cgroup[0], "K");
+ if (!cgroup[9])
+ goto cleanup;
+
+ for (i = 0; i < 10; i++)
+ if (cg_create(cgroup[i]))
+ goto cleanup;
+
+ pids[0] = cg_run_nowait(cgroup[2], child_fn, NULL);
+ pids[1] = cg_run_nowait(cgroup[7], child_fn, NULL);
+ pids[2] = cg_run_nowait(cgroup[9], child_fn, NULL);
+ pids[3] = cg_run_nowait(cgroup[9], child_fn, NULL);
+ pids[4] = cg_run_nowait(cgroup[9], child_fn, NULL);
+
+ /*
+ * Wait until all child processes will enter
+ * corresponding cgroups.
+ */
+
+ if (cg_wait_for_proc_count(cgroup[2], 1) ||
+ cg_wait_for_proc_count(cgroup[7], 1) ||
+ cg_wait_for_proc_count(cgroup[9], 3))
+ goto cleanup;
+
+ /*
+ * Kill A and check that we get an empty notification.
+ */
+ if (cg_kill_wait(cgroup[0]))
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ for (i = 0; i < 5; i++)
+ wait_for_pid(pids[i]);
+
+ if (ret == KSFT_PASS &&
+ cg_read_strcmp(cgroup[0], "cgroup.events", "populated 0\n"))
+ ret = KSFT_FAIL;
+
+ for (i = 9; i >= 0 && cgroup[i]; i--) {
+ cg_destroy(cgroup[i]);
+ free(cgroup[i]);
+ }
+
+ return ret;
+}
+
+static int forkbomb_fn(const char *cgroup, void *arg)
+{
+ int ppid;
+
+ fork();
+ fork();
+
+ ppid = getppid();
+
+ while (getppid() == ppid)
+ usleep(1000);
+
+ return getppid() == ppid;
+}
+
+/*
+ * The test runs a fork bomb in a cgroup and tries to kill it.
+ */
+static int test_cgkill_forkbomb(const char *root)
+{
+ int ret = KSFT_FAIL;
+ char *cgroup = NULL;
+ pid_t pid = -ESRCH;
+
+ cgroup = cg_name(root, "cg_forkbomb_test");
+ if (!cgroup)
+ goto cleanup;
+
+ if (cg_create(cgroup))
+ goto cleanup;
+
+ pid = cg_run_nowait(cgroup, forkbomb_fn, NULL);
+ if (pid < 0)
+ goto cleanup;
+
+ usleep(100000);
+
+ if (cg_kill_wait(cgroup))
+ goto cleanup;
+
+ if (cg_wait_for_proc_count(cgroup, 0))
+ goto cleanup;
+
+ ret = KSFT_PASS;
+
+cleanup:
+ if (pid > 0)
+ wait_for_pid(pid);
+
+ if (ret == KSFT_PASS &&
+ cg_read_strcmp(cgroup, "cgroup.events", "populated 0\n"))
+ ret = KSFT_FAIL;
+
+ if (cgroup)
+ cg_destroy(cgroup);
+ free(cgroup);
+ return ret;
+}
+
+#define T(x) { x, #x }
+struct cgkill_test {
+ int (*fn)(const char *root);
+ const char *name;
+} tests[] = {
+ T(test_cgkill_simple),
+ T(test_cgkill_tree),
+ T(test_cgkill_forkbomb),
+};
+#undef T
+
+int main(int argc, char *argv[])
+{
+ char root[PATH_MAX];
+ int i, ret = EXIT_SUCCESS;
+
+ if (cg_find_unified_root(root, sizeof(root)))
+ ksft_exit_skip("cgroup v2 isn't mounted\n");
+ for (i = 0; i < ARRAY_SIZE(tests); i++) {
+ switch (tests[i].fn(root)) {
+ case KSFT_PASS:
+ ksft_test_result_pass("%s\n", tests[i].name);
+ break;
+ case KSFT_SKIP:
+ ksft_test_result_skip("%s\n", tests[i].name);
+ break;
+ default:
+ ret = EXIT_FAILURE;
+ ksft_test_result_fail("%s\n", tests[i].name);
+ break;
+ }
+ }
+
+ return ret;
+}