sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

alb_break_llc() decides whether to break LLC preference during active
load balance. It does so by testing that every runnable fair task on the
source rq prefers its LLC:

	env->src_rq->nr_pref_llc_running == env->src_rq->cfs.h_nr_runnable

But the two counters cover different sets. nr_pref_llc_running is updated
in account_llc_enqueue()/account_llc_dequeue(), next to cfs_rq->nr_queued,
so it follows queued tasks. h_nr_runnable is updated in set_delayed()/
clear_delayed() and drops delay-dequeued tasks.

So under DELAY_DEQUEUE, a preferring task that goes to sleep stays counted
in nr_pref_llc_running while h_nr_runnable falls. The equality then breaks,
alb_break_llc() returns false, and active balance is free to pull a task
off its preferred LLC. Active balance only moves runnable tasks, and this
is the only LLC check it consults: once the stopper runs, LBF_ACTIVE_LB
skips the per-task test in can_migrate_task(). The runnable set is the one
we want.

Fix it on the counter side. A task should be counted in
nr_pref_llc_running exactly while it is both queued on its preferred LLC
(pref_llc_queued) and runnable (!sched_delayed). Define that membership
once in task_pref_llc_runnable(), and adjust the counter only through
pref_llc_running_inc()/pref_llc_running_dec() from the four sites that
change either input: account_llc_enqueue(), account_llc_dequeue(),
set_delayed() and clear_delayed(). Gating every update on the same
predicate keeps the delay, wake and dequeue paths from double-counting
or underflowing; see the comments at those sites for the ordering.

nr_llc_running and sd->llc_counts are not touched and stay on queued
semantics.

Fixes: 714059f79ff0 ("sched/cache: Handle moving single tasks to/from their preferred LLC")
Closes: https://lore.kernel.org/lkml/20260827135000.735138-1-zhanxusheng@xiaomi.com/
Reported-by: Zhan Xusheng <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 313 insertions, 0 deletions

diff --git a/crypto/aead.c b/crypto/aead.c
new file mode 100644
index 000000000..045b74c37
--- /dev/null
+++ b/crypto/aead.c
@@ -0,0 +1,313 @@
+// SPDX-License-Identifier: GPL-2.0-or-later
+/*
+ * AEAD: Authenticated Encryption with Associated Data
+ *
+ * This file provides API support for AEAD algorithms.
+ *
+ * Copyright (c) 2007-2015 Herbert Xu <herbert@gondor.apana.org.au>
+ */
+
+#include <crypto/internal/aead.h>
+#include <linux/cryptouser.h>
+#include <linux/errno.h>
+#include <linux/init.h>
+#include <linux/kernel.h>
+#include <linux/module.h>
+#include <linux/slab.h>
+#include <linux/seq_file.h>
+#include <linux/string.h>
+#include <linux/string_choices.h>
+#include <net/netlink.h>
+
+#include "internal.h"
+
+static int setkey_unaligned(struct crypto_aead *tfm, const u8 *key,
+			    unsigned int keylen)
+{
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int ret;
+	u8 *buffer, *alignbuffer;
+	unsigned long absize;
+
+	absize = keylen + alignmask;
+	buffer = kmalloc(absize, GFP_ATOMIC);
+	if (!buffer)
+		return -ENOMEM;
+
+	alignbuffer = (u8 *)ALIGN((unsigned long)buffer, alignmask + 1);
+	memcpy(alignbuffer, key, keylen);
+	ret = crypto_aead_alg(tfm)->setkey(tfm, alignbuffer, keylen);
+	kfree_sensitive(buffer);
+	return ret;
+}
+
+int crypto_aead_setkey(struct crypto_aead *tfm,
+		       const u8 *key, unsigned int keylen)
+{
+	unsigned long alignmask = crypto_aead_alignmask(tfm);
+	int err;
+
+	if ((unsigned long)key & alignmask)
+		err = setkey_unaligned(tfm, key, keylen);
+	else
+		err = crypto_aead_alg(tfm)->setkey(tfm, key, keylen);
+
+	if (unlikely(err)) {
+		crypto_aead_set_flags(tfm, CRYPTO_TFM_NEED_KEY);
+		return err;
+	}
+
+	crypto_aead_clear_flags(tfm, CRYPTO_TFM_NEED_KEY);
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_aead_setkey);
+
+int crypto_aead_setauthsize(struct crypto_aead *tfm, unsigned int authsize)
+{
+	int err;
+
+	if ((!authsize && crypto_aead_maxauthsize(tfm)) ||
+	    authsize > crypto_aead_maxauthsize(tfm))
+		return -EINVAL;
+
+	if (crypto_aead_alg(tfm)->setauthsize) {
+		err = crypto_aead_alg(tfm)->setauthsize(tfm, authsize);
+		if (err)
+			return err;
+	}
+
+	tfm->authsize = authsize;
+	return 0;
+}
+EXPORT_SYMBOL_GPL(crypto_aead_setauthsize);
+
+int crypto_aead_encrypt(struct aead_request *req)
+{
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+
+	if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
+	return crypto_aead_alg(aead)->encrypt(req);
+}
+EXPORT_SYMBOL_GPL(crypto_aead_encrypt);
+
+int crypto_aead_decrypt(struct aead_request *req)
+{
+	struct crypto_aead *aead = crypto_aead_reqtfm(req);
+
+	if (crypto_aead_get_flags(aead) & CRYPTO_TFM_NEED_KEY)
+		return -ENOKEY;
+
+	if (req->cryptlen < crypto_aead_authsize(aead))
+		return -EINVAL;
+
+	return crypto_aead_alg(aead)->decrypt(req);
+}
+EXPORT_SYMBOL_GPL(crypto_aead_decrypt);
+
+static void crypto_aead_exit_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *aead = __crypto_aead_cast(tfm);
+	struct aead_alg *alg = crypto_aead_alg(aead);
+
+	alg->exit(aead);
+}
+
+static int crypto_aead_init_tfm(struct crypto_tfm *tfm)
+{
+	struct crypto_aead *aead = __crypto_aead_cast(tfm);
+	struct aead_alg *alg = crypto_aead_alg(aead);
+
+	crypto_aead_set_flags(aead, CRYPTO_TFM_NEED_KEY);
+	crypto_aead_set_reqsize(aead, crypto_tfm_alg_reqsize(tfm));
+
+	aead->authsize = alg->maxauthsize;
+
+	if (alg->exit)
+		aead->base.exit = crypto_aead_exit_tfm;
+
+	if (alg->init)
+		return alg->init(aead);
+
+	return 0;
+}
+
+static int __maybe_unused crypto_aead_report(
+	struct sk_buff *skb, struct crypto_alg *alg)
+{
+	struct aead_alg *aead = container_of(alg, struct aead_alg, base);
+	struct crypto_report_aead raead = {
+		.type = "aead",
+		.geniv = "<none>",
+	};
+
+	raead.blocksize = alg->cra_blocksize;
+	raead.maxauthsize = aead->maxauthsize;
+	raead.ivsize = aead->ivsize;
+
+	return nla_put(skb, CRYPTOCFGA_REPORT_AEAD, sizeof(raead), &raead);
+}
+
+static void __maybe_unused crypto_aead_show(struct seq_file *m,
+					    struct crypto_alg *alg)
+{
+	struct aead_alg *aead = container_of(alg, struct aead_alg, base);
+
+	seq_printf(m, "type         : aead\n");
+	seq_printf(m, "async        : %s\n",
+		   str_yes_no(alg->cra_flags & CRYPTO_ALG_ASYNC));
+	seq_printf(m, "blocksize    : %u\n", alg->cra_blocksize);
+	seq_printf(m, "ivsize       : %u\n", aead->ivsize);
+	seq_printf(m, "maxauthsize  : %u\n", aead->maxauthsize);
+	seq_printf(m, "geniv        : <none>\n");
+}
+
+static void crypto_aead_free_instance(struct crypto_instance *inst)
+{
+	struct aead_instance *aead = aead_instance(inst);
+
+	aead->free(aead);
+}
+
+static const struct crypto_type crypto_aead_type = {
+	.extsize = crypto_alg_extsize,
+	.init_tfm = crypto_aead_init_tfm,
+	.free = crypto_aead_free_instance,
+#ifdef CONFIG_PROC_FS
+	.show = crypto_aead_show,
+#endif
+#if IS_ENABLED(CONFIG_CRYPTO_USER)
+	.report = crypto_aead_report,
+#endif
+	.maskclear = ~CRYPTO_ALG_TYPE_MASK,
+	.maskset = CRYPTO_ALG_TYPE_MASK,
+	.type = CRYPTO_ALG_TYPE_AEAD,
+	.tfmsize = offsetof(struct crypto_aead, base),
+	.algsize = offsetof(struct aead_alg, base),
+};
+
+int crypto_grab_aead(struct crypto_aead_spawn *spawn,
+		     struct crypto_instance *inst,
+		     const char *name, u32 type, u32 mask)
+{
+	spawn->base.frontend = &crypto_aead_type;
+	return crypto_grab_spawn(&spawn->base, inst, name, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_grab_aead);
+
+struct crypto_aead *crypto_alloc_aead(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_alloc_tfm(alg_name, &crypto_aead_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_aead);
+
+struct crypto_sync_aead *crypto_alloc_sync_aead(const char *alg_name, u32 type, u32 mask)
+{
+	struct crypto_aead *tfm;
+
+	/* Only sync algorithms are allowed. */
+	mask |= CRYPTO_ALG_ASYNC;
+	type &= ~(CRYPTO_ALG_ASYNC);
+
+	tfm = crypto_alloc_tfm(alg_name, &crypto_aead_type, type, mask);
+
+	if (!IS_ERR(tfm) && WARN_ON(crypto_aead_reqsize(tfm) > MAX_SYNC_AEAD_REQSIZE)) {
+		crypto_free_aead(tfm);
+		return ERR_PTR(-EINVAL);
+	}
+
+	return (struct crypto_sync_aead *)tfm;
+}
+EXPORT_SYMBOL_GPL(crypto_alloc_sync_aead);
+
+int crypto_has_aead(const char *alg_name, u32 type, u32 mask)
+{
+	return crypto_type_has_alg(alg_name, &crypto_aead_type, type, mask);
+}
+EXPORT_SYMBOL_GPL(crypto_has_aead);
+
+static int aead_prepare_alg(struct aead_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+
+	if (max3(alg->maxauthsize, alg->ivsize, alg->chunksize) >
+	    PAGE_SIZE / 8)
+		return -EINVAL;
+
+	if (!alg->chunksize)
+		alg->chunksize = base->cra_blocksize;
+
+	base->cra_type = &crypto_aead_type;
+	base->cra_flags &= ~CRYPTO_ALG_TYPE_MASK;
+	base->cra_flags |= CRYPTO_ALG_TYPE_AEAD;
+
+	return 0;
+}
+
+int crypto_register_aead(struct aead_alg *alg)
+{
+	struct crypto_alg *base = &alg->base;
+	int err;
+
+	err = aead_prepare_alg(alg);
+	if (err)
+		return err;
+
+	return crypto_register_alg(base);
+}
+EXPORT_SYMBOL_GPL(crypto_register_aead);
+
+void crypto_unregister_aead(struct aead_alg *alg)
+{
+	crypto_unregister_alg(&alg->base);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_aead);
+
+int crypto_register_aeads(struct aead_alg *algs, int count)
+{
+	int i, ret;
+
+	for (i = 0; i < count; i++) {
+		ret = crypto_register_aead(&algs[i]);
+		if (ret)
+			goto err;
+	}
+
+	return 0;
+
+err:
+	for (--i; i >= 0; --i)
+		crypto_unregister_aead(&algs[i]);
+
+	return ret;
+}
+EXPORT_SYMBOL_GPL(crypto_register_aeads);
+
+void crypto_unregister_aeads(struct aead_alg *algs, int count)
+{
+	int i;
+
+	for (i = count - 1; i >= 0; --i)
+		crypto_unregister_aead(&algs[i]);
+}
+EXPORT_SYMBOL_GPL(crypto_unregister_aeads);
+
+int aead_register_instance(struct crypto_template *tmpl,
+			   struct aead_instance *inst)
+{
+	int err;
+
+	if (WARN_ON(!inst->free))
+		return -EINVAL;
+
+	err = aead_prepare_alg(&inst->alg);
+	if (err)
+		return err;
+
+	return crypto_register_instance(tmpl, aead_crypto_instance(inst));
+}
+EXPORT_SYMBOL_GPL(aead_register_instance);
+
+MODULE_LICENSE("GPL");
+MODULE_DESCRIPTION("Authenticated Encryption with Associated Data (AEAD)");