From 0d6526f82c3cdefcca47f73f5fc08dc6f335eac6 Mon Sep 17 00:00:00 2001 From: Tim Chen Date: Mon, 21 Sep 2026 17:37:22 -0700 Subject: sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling bug 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 Suggested-by: Chen Yu Signed-off-by: Tim Chen Signed-off-by: Peter Zijlstra (Intel) Signed-off-by: Ingo Molnar Reviewed-by: Kayra Cizmeci Cc: # v7.2.x Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com --- net/ceph/crypto.h | 53 +++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 53 insertions(+) create mode 100644 net/ceph/crypto.h (limited to 'net/ceph/crypto.h') diff --git a/net/ceph/crypto.h b/net/ceph/crypto.h new file mode 100644 index 000000000..3a2ade15a --- /dev/null +++ b/net/ceph/crypto.h @@ -0,0 +1,53 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +#ifndef _FS_CEPH_CRYPTO_H +#define _FS_CEPH_CRYPTO_H + +#include +#include +#include + +#define CEPH_MAX_KEY_LEN 32 +#define CEPH_MAX_CON_SECRET_LEN 64 + +/* + * cryptographic secret + */ +struct ceph_crypto_key { + int type; + struct ceph_timespec created; + int len; + void *key; + + union { + struct crypto_sync_skcipher *aes_tfm; + struct { + struct hmac_sha256_key hmac_key; + const struct krb5_enctype *krb5_type; + struct crypto_aead *krb5_tfms[3]; + }; + }; +}; + +int ceph_crypto_key_prepare(struct ceph_crypto_key *key, + const u32 *key_usages, int key_usage_cnt); +int ceph_crypto_key_clone(struct ceph_crypto_key *dst, + const struct ceph_crypto_key *src); +int ceph_crypto_key_decode(struct ceph_crypto_key *key, void **p, void *end); +int ceph_crypto_key_unarmor(struct ceph_crypto_key *key, const char *in); +void ceph_crypto_key_destroy(struct ceph_crypto_key *key); + +/* crypto.c */ +int ceph_crypt(const struct ceph_crypto_key *key, int usage_slot, bool encrypt, + void *buf, int buf_len, int in_len, int *pout_len); +int ceph_crypt_data_offset(const struct ceph_crypto_key *key); +int ceph_crypt_buflen(const struct ceph_crypto_key *key, int data_len); +void ceph_hmac_sha256(const struct ceph_crypto_key *key, const void *buf, + int buf_len, u8 hmac[SHA256_DIGEST_SIZE]); +int ceph_crypto_init(void); +void ceph_crypto_shutdown(void); + +/* armor.c */ +int ceph_armor(char *dst, const char *src, const char *end); +int ceph_unarmor(char *dst, const char *src, const char *end); + +#endif -- cgit v1.3.1