sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

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 <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

2 files changed, 191 insertions, 0 deletions

diff --git a/Documentation/devicetree/bindings/npu/arm,ethos.yaml b/Documentation/devicetree/bindings/npu/arm,ethos.yaml
new file mode 100644
index 000000000..d5a1fae4d
--- /dev/null
+++ b/Documentation/devicetree/bindings/npu/arm,ethos.yaml
@@ -0,0 +1,79 @@
+# SPDX-License-Identifier: GPL-2.0-only OR BSD-2-Clause
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/npu/arm,ethos.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Arm Ethos U65/U85
+
+maintainers:
+  - Rob Herring <robh@kernel.org>
+
+description: >
+  The Arm Ethos-U NPUs are designed for IoT inference applications. The NPUs
+  can accelerate 8-bit and 16-bit integer quantized networks:
+
+    Transformer networks (U85 only)
+    Convolutional Neural Networks (CNN)
+    Recurrent Neural Networks (RNN)
+
+  Further documentation is available here:
+
+    U65 TRM: https://developer.arm.com/documentation/102023/
+    U85 TRM: https://developer.arm.com/documentation/102685/
+
+properties:
+  compatible:
+    oneOf:
+      - items:
+          - enum:
+              - fsl,imx93-npu
+          - const: arm,ethos-u65
+      - items:
+          - const: arm,corstone1000-ethos-u85
+          - const: arm,ethos-u85
+
+  reg:
+    maxItems: 1
+
+  interrupts:
+    maxItems: 1
+
+  clocks:
+    maxItems: 2
+
+  clock-names:
+    items:
+      - const: core
+      - const: apb
+
+  power-domains:
+    maxItems: 1
+
+  sram:
+    maxItems: 1
+
+required:
+  - compatible
+  - reg
+  - interrupts
+  - clocks
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/clock/imx93-clock.h>
+
+    npu@4a900000 {
+        compatible = "fsl,imx93-npu", "arm,ethos-u65";
+        reg = <0x4a900000 0x1000>;
+        interrupts = <GIC_SPI 178 IRQ_TYPE_LEVEL_HIGH>;
+        power-domains = <&mlmix>;
+        clocks = <&clk IMX93_CLK_ML>, <&clk IMX93_CLK_ML_APB>;
+        clock-names = "core", "apb";
+        sram = <&sram>;
+    };
+...
diff --git a/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
new file mode 100644
index 000000000..caca2a490
--- /dev/null
+++ b/Documentation/devicetree/bindings/npu/rockchip,rk3588-rknn-core.yaml
@@ -0,0 +1,112 @@
+# SPDX-License-Identifier: (GPL-2.0-only OR BSD-2-Clause)
+%YAML 1.2
+---
+$id: http://devicetree.org/schemas/npu/rockchip,rk3588-rknn-core.yaml#
+$schema: http://devicetree.org/meta-schemas/core.yaml#
+
+title: Neural Processing Unit IP from Rockchip
+
+maintainers:
+  - Tomeu Vizoso <tomeu@tomeuvizoso.net>
+
+description:
+  Rockchip IP for accelerating inference of neural networks.
+
+  There is to be a node per each NPU core in the SoC, and each core should reference all the
+  resources that it needs to function, such as clocks, power domains, and resets.
+
+properties:
+  $nodename:
+    pattern: '^npu@[a-f0-9]+$'
+
+  compatible:
+    enum:
+      - rockchip,rk3588-rknn-core
+
+  reg:
+    maxItems: 3
+
+  reg-names:
+    items:
+      - const: pc # Program Control-related registers
+      - const: cna # Convolution Neural Network Accelerator registers
+      - const: core # Main NPU core processing unit registers
+
+  clocks:
+    maxItems: 4
+
+  clock-names:
+    items:
+      - const: aclk
+      - const: hclk
+      - const: npu
+      - const: pclk
+
+  interrupts:
+    maxItems: 1
+
+  iommus:
+    maxItems: 1
+
+  npu-supply: true
+
+  power-domains:
+    maxItems: 1
+
+  resets:
+    maxItems: 2
+
+  reset-names:
+    items:
+      - const: srst_a
+      - const: srst_h
+
+  sram-supply: true
+
+required:
+  - compatible
+  - reg
+  - reg-names
+  - clocks
+  - clock-names
+  - interrupts
+  - iommus
+  - power-domains
+  - resets
+  - reset-names
+  - npu-supply
+  - sram-supply
+
+additionalProperties: false
+
+examples:
+  - |
+    #include <dt-bindings/clock/rockchip,rk3588-cru.h>
+    #include <dt-bindings/interrupt-controller/irq.h>
+    #include <dt-bindings/interrupt-controller/arm-gic.h>
+    #include <dt-bindings/power/rk3588-power.h>
+    #include <dt-bindings/reset/rockchip,rk3588-cru.h>
+
+    bus {
+      #address-cells = <2>;
+      #size-cells = <2>;
+
+      npu@fdab0000 {
+        compatible = "rockchip,rk3588-rknn-core";
+        reg = <0x0 0xfdab0000 0x0 0x1000>,
+              <0x0 0xfdab1000 0x0 0x1000>,
+              <0x0 0xfdab3000 0x0 0x1000>;
+        reg-names = "pc", "cna", "core";
+        clocks = <&cru ACLK_NPU0>, <&cru HCLK_NPU0>,
+                 <&scmi_clk SCMI_CLK_NPU>, <&cru PCLK_NPU_ROOT>;
+        clock-names = "aclk", "hclk", "npu", "pclk";
+        interrupts = <GIC_SPI 110 IRQ_TYPE_LEVEL_HIGH 0>;
+        iommus = <&rknn_mmu_0>;
+        npu-supply = <&vdd_npu_s0>;
+        power-domains = <&power RK3588_PD_NPUTOP>;
+        resets = <&cru SRST_A_RKNN0>, <&cru SRST_H_RKNN0>;
+        reset-names = "srst_a", "srst_h";
+        sram-supply = <&vdd_npu_mem_s0>;
+      };
+    };
+...