Commit 58624e4b authored by Linus Torvalds's avatar Linus Torvalds
Browse files

Merge tag 'cgroup-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup 

Pull cgroup fixes from Tejun Heo:
 "Cpuset fixes:

   - Fix isolated CPUs leaking into sched domains

   - Remove now unnecessary kernfs active break which can trigger a
     warning

   - Comment updates"

* tag 'cgroup-for-6.13-rc6-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/cpuset: remove kernfs active break
  cgroup/cpuset: Prevent leakage of isolated CPUs into sched domains
  cgroup/cpuset: Remove stale text
parents 257a8be4 3cb97a92

kernel/cgroup/cpuset.c

+11 −33
Original line number Diff line number Diff line
@@ -197,10 +197,8 @@ static struct cpuset top_cpuset = { 


/*

 * There are two global locks guarding cpuset structures - cpuset_mutex and

 * callback_lock. We also require taking task_lock() when dereferencing a

 * task's cpuset pointer. See "The task_lock() exception", at the end of this

 * comment.  The cpuset code uses only cpuset_mutex. Other kernel subsystems

 * can use cpuset_lock()/cpuset_unlock() to prevent change to cpuset

 * callback_lock. The cpuset code uses only cpuset_mutex. Other kernel

 * subsystems can use cpuset_lock()/cpuset_unlock() to prevent change to cpuset

 * structures. Note that cpuset_mutex needs to be a mutex as it is used in

 * paths that rely on priority inheritance (e.g. scheduler - on RT) for

 * correctness.
@@ -229,9 +227,6 @@ static struct cpuset top_cpuset = { 
 * The cpuset_common_seq_show() handlers only hold callback_lock across

 * small pieces of code, such as when reading out possibly multi-word

 * cpumasks and nodemasks.

 *

 * Accessing a task's cpuset should be done in accordance with the

 * guidelines for accessing subsystem state in kernel/cgroup.c

 */



static DEFINE_MUTEX(cpuset_mutex);
@@ -890,6 +885,14 @@ static int generate_sched_domains(cpumask_var_t **domains, 
	 */

	if (cgrpv2) {

		for (i = 0; i < ndoms; i++) {

			/*

			 * The top cpuset may contain some boot time isolated

			 * CPUs that need to be excluded from the sched domain.

			 */

			if (csa[i] == &top_cpuset)

				cpumask_and(doms[i], csa[i]->effective_cpus,

					    housekeeping_cpumask(HK_TYPE_DOMAIN));

			else

				cpumask_copy(doms[i], csa[i]->effective_cpus);

			if (dattr)

				dattr[i] = SD_ATTR_INIT;
@@ -3121,29 +3124,6 @@ ssize_t cpuset_write_resmask(struct kernfs_open_file *of, 
	int retval = -ENODEV;



	buf = strstrip(buf);



	/*

	 * CPU or memory hotunplug may leave @cs w/o any execution

	 * resources, in which case the hotplug code asynchronously updates

	 * configuration and transfers all tasks to the nearest ancestor

	 * which can execute.

	 *

	 * As writes to "cpus" or "mems" may restore @cs's execution

	 * resources, wait for the previously scheduled operations before

	 * proceeding, so that we don't end up keep removing tasks added

	 * after execution capability is restored.

	 *

	 * cpuset_handle_hotplug may call back into cgroup core asynchronously

	 * via cgroup_transfer_tasks() and waiting for it from a cgroupfs

	 * operation like this one can lead to a deadlock through kernfs

	 * active_ref protection.  Let's break the protection.  Losing the

	 * protection is okay as we check whether @cs is online after

	 * grabbing cpuset_mutex anyway.  This only happens on the legacy

	 * hierarchies.

	 */

	css_get(&cs->css);

	kernfs_break_active_protection(of->kn);



	cpus_read_lock();

	mutex_lock(&cpuset_mutex);

	if (!is_cpuset_online(cs))
@@ -3176,8 +3156,6 @@ ssize_t cpuset_write_resmask(struct kernfs_open_file *of, 
out_unlock:

	mutex_unlock(&cpuset_mutex);

	cpus_read_unlock();

	kernfs_unbreak_active_protection(of->kn);

	css_put(&cs->css);

	flush_workqueue(cpuset_migrate_mm_wq);

	return retval ?: nbytes;

}

tools/testing/selftests/cgroup/test_cpuset_prs.sh

+19 −14
Original line number Diff line number Diff line
@@ -86,15 +86,15 @@ echo "" > test/cpuset.cpus 


#

# If isolated CPUs have been reserved at boot time (as shown in

# cpuset.cpus.isolated), these isolated CPUs should be outside of CPUs 0-7

# cpuset.cpus.isolated), these isolated CPUs should be outside of CPUs 0-8

# that will be used by this script for testing purpose. If not, some of

# the tests may fail incorrectly. These isolated CPUs will also be removed

# before being compared with the expected results.

# the tests may fail incorrectly. These pre-isolated CPUs should stay in

# an isolated state throughout the testing process for now.

#

BOOT_ISOLCPUS=$(cat $CGROUP2/cpuset.cpus.isolated)

if [[ -n "$BOOT_ISOLCPUS" ]]

then

	[[ $(echo $BOOT_ISOLCPUS | sed -e "s/[,-].*//") -le 7 ]] &&

	[[ $(echo $BOOT_ISOLCPUS | sed -e "s/[,-].*//") -le 8 ]] &&

		skip_test "Pre-isolated CPUs ($BOOT_ISOLCPUS) overlap CPUs to be tested"

	echo "Pre-isolated CPUs: $BOOT_ISOLCPUS"

fi
@@ -683,15 +683,19 @@ check_isolcpus() 
		EXPECT_VAL2=$EXPECT_VAL

	fi



	#

	# Appending pre-isolated CPUs

	# Even though CPU #8 isn't used for testing, it can't be pre-isolated

	# to make appending those CPUs easier.

	#

	[[ -n "$BOOT_ISOLCPUS" ]] && {

		EXPECT_VAL=${EXPECT_VAL:+${EXPECT_VAL},}${BOOT_ISOLCPUS}

		EXPECT_VAL2=${EXPECT_VAL2:+${EXPECT_VAL2},}${BOOT_ISOLCPUS}

	}



	#

	# Check cpuset.cpus.isolated cpumask

	#

	if [[ -z "$BOOT_ISOLCPUS" ]]

	then

		ISOLCPUS=$(cat $ISCPUS)

	else

		ISOLCPUS=$(cat $ISCPUS | sed -e "s/,*$BOOT_ISOLCPUS//")

	fi

	[[ "$EXPECT_VAL2" != "$ISOLCPUS" ]] && {

		# Take a 50ms pause and try again

		pause 0.05
@@ -731,8 +735,6 @@ check_isolcpus() 
		fi

	done

	[[ "$ISOLCPUS" = *- ]] && ISOLCPUS=${ISOLCPUS}$LASTISOLCPU

	[[ -n "BOOT_ISOLCPUS" ]] &&

		ISOLCPUS=$(echo $ISOLCPUS | sed -e "s/,*$BOOT_ISOLCPUS//")



	[[ "$EXPECT_VAL" = "$ISOLCPUS" ]]

}
@@ -836,9 +838,12 @@ run_state_test() 
		# if available

		[[ -n "$ICPUS" ]] && {

			check_isolcpus $ICPUS

			[[ $? -ne 0 ]] && test_fail $I "isolated CPU" \

			[[ $? -ne 0 ]] && {

				[[ -n "$BOOT_ISOLCPUS" ]] && ICPUS=${ICPUS},${BOOT_ISOLCPUS}

				test_fail $I "isolated CPU" \

					"Expect $ICPUS, get $ISOLCPUS instead"

			}

		}

		reset_cgroup_states

		#

		# Check to see if effective cpu list changes