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/uapi/rdma/ionic-abi.h | 116 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 116 insertions(+) create mode 100644 include/uapi/rdma/ionic-abi.h (limited to 'include/uapi/rdma/ionic-abi.h') diff --git a/include/uapi/rdma/ionic-abi.h b/include/uapi/rdma/ionic-abi.h new file mode 100644 index 000000000..2c70ac149 --- /dev/null +++ b/include/uapi/rdma/ionic-abi.h @@ -0,0 +1,116 @@ +/* SPDX-License-Identifier: GPL-2.0 WITH Linux-syscall-note */ +/* Copyright (C) 2018-2025, Advanced Micro Devices, Inc */ + +#ifndef IONIC_ABI_H +#define IONIC_ABI_H + +#include + +#define IONIC_ABI_VERSION 1 + +#define IONIC_EXPDB_64 1 +#define IONIC_EXPDB_128 2 +#define IONIC_EXPDB_256 4 +#define IONIC_EXPDB_512 8 + +#define IONIC_EXPDB_SQ 1 +#define IONIC_EXPDB_RQ 2 + +#define IONIC_CMB_ENABLE 1 +#define IONIC_CMB_REQUIRE 2 +#define IONIC_CMB_EXPDB 4 +#define IONIC_CMB_WC 8 +#define IONIC_CMB_UC 16 + +struct ionic_ctx_req { + __u32 rsvd[2]; +}; + +struct ionic_ctx_resp { + __u32 rsvd; + __u32 page_shift; + + __aligned_u64 dbell_offset; + + __u16 version; + __u8 qp_opcodes; + __u8 admin_opcodes; + + __u8 sq_qtype; + __u8 rq_qtype; + __u8 cq_qtype; + __u8 admin_qtype; + + __u8 max_stride; + __u8 max_spec; + __u8 udma_count; + __u8 expdb_mask; + __u8 expdb_qtypes; + + __u8 rsvd2[3]; + __aligned_u64 phc_offset; +}; + +struct ionic_qdesc { + __aligned_u64 addr; + __u32 size; + __u16 mask; + __u8 depth_log2; + __u8 stride_log2; +}; + +struct ionic_ah_resp { + __u32 ahid; + __u32 pad; +}; + +struct ionic_cq_req { + struct ionic_qdesc cq[2]; + __u8 udma_mask; + __u8 rsvd[7]; +}; + +struct ionic_cq_resp { + __u32 cqid[2]; + __u8 udma_mask; + __u8 rsvd[7]; +}; + +struct ionic_qp_req { + struct ionic_qdesc sq; + struct ionic_qdesc rq; + __u8 sq_spec; + __u8 rq_spec; + __u8 sq_cmb; + __u8 rq_cmb; + __u8 udma_mask; + __u8 rsvd[3]; +}; + +struct ionic_qp_resp { + __u32 qpid; + __u8 sq_cmb; + __u8 rq_cmb; + __u8 udma_idx; + __u8 rsvd[1]; + __aligned_u64 sq_cmb_offset; + __aligned_u64 rq_cmb_offset; +}; + +struct ionic_srq_req { + struct ionic_qdesc rq; + __u8 rq_spec; + __u8 rq_cmb; + __u8 udma_mask; + __u8 rsvd[5]; +}; + +struct ionic_srq_resp { + __u32 qpid; + __u8 rq_cmb; + __u8 udma_idx; + __u8 rsvd[2]; + __aligned_u64 rq_cmb_offset; +}; + +#endif /* IONIC_ABI_H */ -- cgit v1.3.1