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/firmware/imx/misc.c | 137 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 137 insertions(+) create mode 100644 drivers/firmware/imx/misc.c (limited to 'drivers/firmware/imx/misc.c') diff --git a/drivers/firmware/imx/misc.c b/drivers/firmware/imx/misc.c new file mode 100644 index 000000000..d073cb3ce --- /dev/null +++ b/drivers/firmware/imx/misc.c @@ -0,0 +1,137 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright (C) 2016 Freescale Semiconductor, Inc. + * Copyright 2017~2018 NXP + * Author: Dong Aisheng + * + * File containing client-side RPC functions for the MISC service. These + * function are ported to clients that communicate to the SC. + * + */ + +#include + +struct imx_sc_msg_req_misc_set_ctrl { + struct imx_sc_rpc_msg hdr; + u32 ctrl; + u32 val; + u16 resource; +} __packed __aligned(4); + +struct imx_sc_msg_req_cpu_start { + struct imx_sc_rpc_msg hdr; + u32 address_hi; + u32 address_lo; + u16 resource; + u8 enable; +} __packed __aligned(4); + +struct imx_sc_msg_req_misc_get_ctrl { + struct imx_sc_rpc_msg hdr; + u32 ctrl; + u16 resource; +} __packed __aligned(4); + +struct imx_sc_msg_resp_misc_get_ctrl { + struct imx_sc_rpc_msg hdr; + u32 val; +} __packed __aligned(4); + +/* + * This function sets a miscellaneous control value. + * + * @param[in] ipc IPC handle + * @param[in] resource resource the control is associated with + * @param[in] ctrl control to change + * @param[in] val value to apply to the control + * + * @return Returns 0 for success and < 0 for errors. + */ + +int imx_sc_misc_set_control(struct imx_sc_ipc *ipc, u32 resource, + u8 ctrl, u32 val) +{ + struct imx_sc_msg_req_misc_set_ctrl msg; + struct imx_sc_rpc_msg *hdr = &msg.hdr; + + hdr->ver = IMX_SC_RPC_VERSION; + hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC; + hdr->func = (uint8_t)IMX_SC_MISC_FUNC_SET_CONTROL; + hdr->size = 4; + + msg.ctrl = ctrl; + msg.val = val; + msg.resource = resource; + + return imx_scu_call_rpc(ipc, &msg, true); +} +EXPORT_SYMBOL(imx_sc_misc_set_control); + +/* + * This function gets a miscellaneous control value. + * + * @param[in] ipc IPC handle + * @param[in] resource resource the control is associated with + * @param[in] ctrl control to get + * @param[out] val pointer to return the control value + * + * @return Returns 0 for success and < 0 for errors. + */ + +int imx_sc_misc_get_control(struct imx_sc_ipc *ipc, u32 resource, + u8 ctrl, u32 *val) +{ + struct imx_sc_msg_req_misc_get_ctrl msg; + struct imx_sc_msg_resp_misc_get_ctrl *resp; + struct imx_sc_rpc_msg *hdr = &msg.hdr; + int ret; + + hdr->ver = IMX_SC_RPC_VERSION; + hdr->svc = (uint8_t)IMX_SC_RPC_SVC_MISC; + hdr->func = (uint8_t)IMX_SC_MISC_FUNC_GET_CONTROL; + hdr->size = 3; + + msg.ctrl = ctrl; + msg.resource = resource; + + ret = imx_scu_call_rpc(ipc, &msg, true); + if (ret) + return ret; + + resp = (struct imx_sc_msg_resp_misc_get_ctrl *)&msg; + if (val != NULL) + *val = resp->val; + + return 0; +} +EXPORT_SYMBOL(imx_sc_misc_get_control); + +/* + * This function starts/stops a CPU identified by @resource + * + * @param[in] ipc IPC handle + * @param[in] resource resource the control is associated with + * @param[in] enable true for start, false for stop + * @param[in] phys_addr initial instruction address to be executed + * + * @return Returns 0 for success and < 0 for errors. + */ +int imx_sc_pm_cpu_start(struct imx_sc_ipc *ipc, u32 resource, + bool enable, u64 phys_addr) +{ + struct imx_sc_msg_req_cpu_start msg; + struct imx_sc_rpc_msg *hdr = &msg.hdr; + + hdr->ver = IMX_SC_RPC_VERSION; + hdr->svc = IMX_SC_RPC_SVC_PM; + hdr->func = IMX_SC_PM_FUNC_CPU_START; + hdr->size = 4; + + msg.address_hi = phys_addr >> 32; + msg.address_lo = phys_addr; + msg.resource = resource; + msg.enable = enable; + + return imx_scu_call_rpc(ipc, &msg, true); +} +EXPORT_SYMBOL(imx_sc_pm_cpu_start); -- cgit v1.3.1