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 --- include/memory/renesas-rpc-if.h | 83 +++++++++++++++++++++++++++++++++++++++++ 1 file changed, 83 insertions(+) create mode 100644 include/memory/renesas-rpc-if.h (limited to 'include/memory') diff --git a/include/memory/renesas-rpc-if.h b/include/memory/renesas-rpc-if.h new file mode 100644 index 000000000..53663c4e5 --- /dev/null +++ b/include/memory/renesas-rpc-if.h @@ -0,0 +1,83 @@ +/* SPDX-License-Identifier: GPL-2.0 */ +/* + * Renesas RPC-IF core driver + * + * Copyright (C) 2018~2019 Renesas Solutions Corp. + * Copyright (C) 2019 Macronix International Co., Ltd. + * Copyright (C) 2019-2020 Cogent Embedded, Inc. + */ + +#ifndef __RENESAS_RPC_IF_H +#define __RENESAS_RPC_IF_H + +#include +#include + +enum rpcif_data_dir { + RPCIF_NO_DATA, + RPCIF_DATA_IN, + RPCIF_DATA_OUT, +}; + +struct rpcif_op { + struct { + u8 buswidth; + u8 opcode; + bool ddr; + } cmd, ocmd; + + struct { + u8 nbytes; + u8 buswidth; + bool ddr; + u64 val; + } addr; + + struct { + u8 ncycles; + u8 buswidth; + } dummy; + + struct { + u8 nbytes; + u8 buswidth; + bool ddr; + u32 val; + } option; + + struct { + u8 buswidth; + unsigned int nbytes; + enum rpcif_data_dir dir; + bool ddr; + union { + void *in; + const void *out; + } buf; + } data; +}; + +enum rpcif_type { + RPCIF_RCAR_GEN3, + RPCIF_RCAR_GEN4, + RPCIF_RZ_G2L, + XSPI_RZ_G3E, +}; + +struct rpcif { + struct device *dev; + void __iomem *dirmap; + size_t size; + bool xspi; +}; + +int rpcif_sw_init(struct rpcif *rpc, struct device *dev); +int rpcif_hw_init(struct device *dev, bool hyperflash); +void rpcif_prepare(struct device *dev, const struct rpcif_op *op, u64 *offs, + size_t *len); +int rpcif_manual_xfer(struct device *dev); +ssize_t rpcif_dirmap_read(struct device *dev, u64 offs, size_t len, void *buf); +ssize_t xspi_dirmap_write(struct device *dev, u64 offs, size_t len, + const void *buf); + +#endif // __RENESAS_RPC_IF_H -- cgit v1.3.1