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 --- drivers/md/dm-ima.h | 118 ++++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 118 insertions(+) create mode 100644 drivers/md/dm-ima.h (limited to 'drivers/md/dm-ima.h') diff --git a/drivers/md/dm-ima.h b/drivers/md/dm-ima.h new file mode 100644 index 000000000..0ec013d15 --- /dev/null +++ b/drivers/md/dm-ima.h @@ -0,0 +1,118 @@ +/* SPDX-License-Identifier: GPL-2.0-only */ +/* + * Copyright (C) 2021 Microsoft Corporation + * + * Author: Tushar Sugandhi + * + * Header file for device mapper IMA measurements. + */ + +#ifndef DM_IMA_H +#define DM_IMA_H + +#define DM_IMA_MEASUREMENT_BUF_LEN 4096 +#define DM_IMA_DEVICE_BUF_LEN 1024 +#define DM_IMA_TARGET_METADATA_BUF_LEN 128 +#define DM_IMA_TARGET_DATA_BUF_LEN 2048 +#define DM_IMA_DEVICE_CAPACITY_BUF_LEN 128 + +#define __dm_ima_stringify(s) #s +#define __dm_ima_str(s) __dm_ima_stringify(s) + +#define DM_IMA_VERSION_STR "dm_version=" \ + __dm_ima_str(DM_VERSION_MAJOR) "." \ + __dm_ima_str(DM_VERSION_MINOR) "." \ + __dm_ima_str(DM_VERSION_PATCHLEVEL) ";" + +enum dm_ima_table_op { + DM_IMA_TABLE_SAVE, + DM_IMA_TABLE_RESTORE, +}; + +#ifdef CONFIG_IMA + +struct dm_ima_device_table_metadata { + /* + * Contains data specific to the device which is common across + * all the targets in the table (e.g. name, uuid, major, minor, etc). + * The values are stored in comma separated list of key1=val1,key2=val2; + * pairs delimited by a semicolon at the end of the list. + */ + char *device_metadata; + unsigned int device_metadata_len; + unsigned int num_targets; + sector_t capacity; + + /* + * Contains the sha256 hashes of the IMA measurements of the target + * attributes' key-value pairs from the active/inactive tables. + */ + char *hash; + unsigned int hash_len; +}; + +struct dm_ima_context { + struct dm_ima_device_table_metadata table; + unsigned int update_idx; + char dev_name[DM_NAME_LEN*2]; + char dev_uuid[DM_UUID_LEN*2]; +}; + +/* + * This structure contains device metadata, and table hash for + * active and inactive tables for ima measurements. + */ +struct dm_ima_measurements { + unsigned int update_idx; + unsigned int measure_idx; + struct wait_queue_head ima_wq; + spinlock_t ima_lock; + struct dm_ima_device_table_metadata active_table; + struct dm_ima_device_table_metadata inactive_table; +}; + +void dm_ima_init(struct mapped_device *md); +void dm_ima_alloc_context(struct dm_ima_context **context, bool noio); +void dm_ima_free_context(struct dm_ima_context *context); +void dm_ima_context_table_op(struct mapped_device *md, + struct dm_ima_context *context, + enum dm_ima_table_op op); +void dm_ima_measure_on_table_load(struct dm_table *table, + struct dm_ima_context *context); +void dm_ima_measure_on_device_resume(struct mapped_device *md, bool swap, + struct dm_ima_context *context); +void dm_ima_measure_on_device_remove(struct mapped_device *md, bool remove_all, + struct dm_ima_context *context, + unsigned int idx); +void dm_ima_measure_on_table_clear(struct mapped_device *md, + struct dm_ima_context *context); +void dm_ima_measure_on_device_rename(struct mapped_device *md, + struct dm_ima_context *context); + +#else + +struct dm_ima_context; + +static inline void dm_ima_init(struct mapped_device *md) {} +static inline void dm_ima_alloc_context(struct dm_ima_context **context, bool noio) {} +static inline void dm_ima_free_context(struct dm_ima_context *context) {} +static inline void dm_ima_context_table_op(struct mapped_device *md, + struct dm_ima_context *context, + enum dm_ima_table_op op) {} +static inline void dm_ima_measure_on_table_load(struct dm_table *table, + struct dm_ima_context *context) {} +static inline void dm_ima_measure_on_device_resume(struct mapped_device *md, + bool swap, + struct dm_ima_context *context) {} +static inline void dm_ima_measure_on_device_remove(struct mapped_device *md, + bool remove_all, + struct dm_ima_context *context, + unsigned int idx) {} +static inline void dm_ima_measure_on_table_clear(struct mapped_device *md, + struct dm_ima_context *context) {} +static inline void dm_ima_measure_on_device_rename(struct mapped_device *md, + struct dm_ima_context *context) {} + +#endif /* CONFIG_IMA */ + +#endif /* DM_IMA_H */ -- cgit v1.3.1