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/rm.c | 90 +++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 drivers/firmware/imx/rm.c (limited to 'drivers/firmware/imx/rm.c') diff --git a/drivers/firmware/imx/rm.c b/drivers/firmware/imx/rm.c new file mode 100644 index 000000000..d492b99e1 --- /dev/null +++ b/drivers/firmware/imx/rm.c @@ -0,0 +1,90 @@ +// SPDX-License-Identifier: GPL-2.0+ +/* + * Copyright 2020 NXP + * + * File containing client-side RPC functions for the RM service. These + * function are ported to clients that communicate to the SC. + */ + +#include + +struct imx_sc_msg_rm_rsrc_owned { + struct imx_sc_rpc_msg hdr; + u16 resource; +} __packed __aligned(4); + +/* + * This function check @resource is owned by current partition or not + * + * @param[in] ipc IPC handle + * @param[in] resource resource the control is associated with + * + * @return Returns 0 for not owned and 1 for owned. + */ +bool imx_sc_rm_is_resource_owned(struct imx_sc_ipc *ipc, u16 resource) +{ + struct imx_sc_msg_rm_rsrc_owned msg; + struct imx_sc_rpc_msg *hdr = &msg.hdr; + + hdr->ver = IMX_SC_RPC_VERSION; + hdr->svc = IMX_SC_RPC_SVC_RM; + hdr->func = IMX_SC_RM_FUNC_IS_RESOURCE_OWNED; + hdr->size = 2; + + msg.resource = resource; + + /* + * SCU firmware only returns value 0 or 1 + * for resource owned check which means not owned or owned. + * So it is always successful. + */ + imx_scu_call_rpc(ipc, &msg, true); + + return hdr->func; +} +EXPORT_SYMBOL(imx_sc_rm_is_resource_owned); + +struct imx_sc_msg_rm_get_resource_owner { + struct imx_sc_rpc_msg hdr; + union { + struct { + u16 resource; + } req; + struct { + u8 val; + } resp; + } data; +} __packed __aligned(4); + +/* + * This function get @resource partition number + * + * @param[in] ipc IPC handle + * @param[in] resource resource the control is associated with + * @param[out] pt pointer to return the partition number + * + * @return Returns 0 for success and < 0 for errors. + */ +int imx_sc_rm_get_resource_owner(struct imx_sc_ipc *ipc, u16 resource, u8 *pt) +{ + struct imx_sc_msg_rm_get_resource_owner msg; + struct imx_sc_rpc_msg *hdr = &msg.hdr; + int ret; + + hdr->ver = IMX_SC_RPC_VERSION; + hdr->svc = IMX_SC_RPC_SVC_RM; + hdr->func = IMX_SC_RM_FUNC_GET_RESOURCE_OWNER; + hdr->size = 2; + + msg.data.req.resource = resource; + + ret = imx_scu_call_rpc(ipc, &msg, true); + if (ret) + return ret; + + if (pt) + *pt = msg.data.resp.val; + + return 0; +} +EXPORT_SYMBOL(imx_sc_rm_get_resource_owner); -- cgit v1.3.1