Merge tag 'cgroup-for-6.18-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup

Pull cgroup fixes from Tejun Heo:

 - Fix seqcount lockdep assertion failure in cgroup freezer on
   PREEMPT_RT.

   Plain seqcount_t expects preemption disabled, but PREEMPT_RT
   spinlocks don't disable preemption. Switch to seqcount_spinlock_t to
   properly associate css_set_lock with the freeze timing seqcount.

 - Misc changes including kernel-doc warning fix for misc_res_type enum
   and improved selftest diagnostics.

* tag 'cgroup-for-6.18-rc2-fixes' of git://git.kernel.org/pub/scm/linux/kernel/git/tj/cgroup:
  cgroup/misc: fix misc_res_type kernel-doc warning
  selftests: cgroup: Use values_close_report in test_cpu
  selftests: cgroup: add values_close_report helper
  cgroup: Fix seqcount lockdep assertion in cgroup freezer

Author: torvalds

include/linux/cgroup-defs.h

@@ -452,7 +452,7 @@ struct cgroup_freezer_state {
 	int nr_frozen_tasks;
 
 	/* Freeze time data consistency protection */
-	seqcount_t freeze_seq;
+	seqcount_spinlock_t freeze_seq;
 
 	/*
 	 * Most recent time the cgroup was requested to freeze.

include/linux/misc_cgroup.h

@@ -19,7 +19,7 @@ enum misc_res_type {
 	MISC_CG_RES_SEV_ES,
 #endif
 #ifdef CONFIG_INTEL_TDX_HOST
-	/* Intel TDX HKIDs resource */
+	/** @MISC_CG_RES_TDX: Intel TDX HKIDs resource */
 	MISC_CG_RES_TDX,
 #endif
 	/** @MISC_CG_RES_TYPES: count of enum misc_res_type constants */

kernel/cgroup/cgroup.c

@@ -5892,7 +5892,7 @@ static struct cgroup *cgroup_create(struct cgroup *parent, const char *name,
 	 * if the parent has to be frozen, the child has too.
 	 */
 	cgrp->freezer.e_freeze = parent->freezer.e_freeze;
-	seqcount_init(&cgrp->freezer.freeze_seq);
+	seqcount_spinlock_init(&cgrp->freezer.freeze_seq, &css_set_lock);
 	if (cgrp->freezer.e_freeze) {
 		/*
 		 * Set the CGRP_FREEZE flag, so when a process will be

tools/testing/selftests/cgroup/lib/include/cgroup_util.h

@@ -25,6 +25,26 @@ static inline int values_close(long a, long b, int err)
 	return labs(a - b) <= (a + b) / 100 * err;
 }
 
+/*
+ * Checks if two given values differ by less than err% of their sum and assert
+ * with detailed debug info if not.
+ */
+static inline int values_close_report(long a, long b, int err)
+{
+	long diff  = labs(a - b);
+	long limit = (a + b) / 100 * err;
+	double actual_err = (a + b) ? (100.0 * diff / (a + b)) : 0.0;
+	int close = diff <= limit;
+
+	if (!close)
+		fprintf(stderr,
+			"[FAIL] actual=%ld expected=%ld | diff=%ld | limit=%ld | "
+			"tolerance=%d%% | actual_error=%.2f%%\n",
+			a, b, diff, limit, err, actual_err);
+
+	return close;
+}
+
 extern ssize_t read_text(const char *path, char *buf, size_t max_len);
 extern ssize_t write_text(const char *path, char *buf, ssize_t len);
 

tools/testing/selftests/cgroup/test_cpu.c

@@ -219,7 +219,7 @@ static int test_cpucg_stats(const char *root)
 	if (user_usec <= 0)
 		goto cleanup;
 
-	if (!values_close(usage_usec, expected_usage_usec, 1))
+	if (!values_close_report(usage_usec, expected_usage_usec, 1))
 		goto cleanup;
 
 	ret = KSFT_PASS;
@@ -291,7 +291,7 @@ static int test_cpucg_nice(const char *root)
 
 		user_usec = cg_read_key_long(cpucg, "cpu.stat", "user_usec");
 		nice_usec = cg_read_key_long(cpucg, "cpu.stat", "nice_usec");
-		if (!values_close(nice_usec, expected_nice_usec, 1))
+		if (!values_close_report(nice_usec, expected_nice_usec, 1))
 			goto cleanup;
 
 		ret = KSFT_PASS;
@@ -404,7 +404,7 @@ overprovision_validate(const struct cpu_hogger *children, int num_children)
 			goto cleanup;
 
 		delta = children[i + 1].usage - children[i].usage;
-		if (!values_close(delta, children[0].usage, 35))
+		if (!values_close_report(delta, children[0].usage, 35))
 			goto cleanup;
 	}
 
@@ -444,7 +444,7 @@ underprovision_validate(const struct cpu_hogger *children, int num_children)
 	int ret = KSFT_FAIL, i;
 
 	for (i = 0; i < num_children - 1; i++) {
-		if (!values_close(children[i + 1].usage, children[0].usage, 15))
+		if (!values_close_report(children[i + 1].usage, children[0].usage, 15))
 			goto cleanup;
 	}
 
@@ -573,16 +573,16 @@ run_cpucg_nested_weight_test(const char *root, bool overprovisioned)
 
 	nested_leaf_usage = leaf[1].usage + leaf[2].usage;
 	if (overprovisioned) {
-		if (!values_close(leaf[0].usage, nested_leaf_usage, 15))
+		if (!values_close_report(leaf[0].usage, nested_leaf_usage, 15))
 			goto cleanup;
-	} else if (!values_close(leaf[0].usage * 2, nested_leaf_usage, 15))
+	} else if (!values_close_report(leaf[0].usage * 2, nested_leaf_usage, 15))
 		goto cleanup;
 
 
 	child_usage = cg_read_key_long(child, "cpu.stat", "usage_usec");
 	if (child_usage <= 0)
 		goto cleanup;
-	if (!values_close(child_usage, nested_leaf_usage, 1))
+	if (!values_close_report(child_usage, nested_leaf_usage, 1))
 		goto cleanup;
 
 	ret = KSFT_PASS;
@@ -691,7 +691,7 @@ static int test_cpucg_max(const char *root)
 	expected_usage_usec
 		= n_periods * quota_usec + MIN(remainder_usec, quota_usec);
 
-	if (!values_close(usage_usec, expected_usage_usec, 10))
+	if (!values_close_report(usage_usec, expected_usage_usec, 10))
 		goto cleanup;
 
 	ret = KSFT_PASS;
@@ -762,7 +762,7 @@ static int test_cpucg_max_nested(const char *root)
 	expected_usage_usec
 		= n_periods * quota_usec + MIN(remainder_usec, quota_usec);
 
-	if (!values_close(usage_usec, expected_usage_usec, 10))
+	if (!values_close_report(usage_usec, expected_usage_usec, 10))
 		goto cleanup;
 
 	ret = KSFT_PASS;