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 --- .../devicetree/bindings/hsi/client-devices.txt | 44 +++++++++ .../devicetree/bindings/hsi/nokia-modem.txt | 59 ++++++++++++ Documentation/devicetree/bindings/hsi/omap-ssi.txt | 102 +++++++++++++++++++++ 3 files changed, 205 insertions(+) create mode 100644 Documentation/devicetree/bindings/hsi/client-devices.txt create mode 100644 Documentation/devicetree/bindings/hsi/nokia-modem.txt create mode 100644 Documentation/devicetree/bindings/hsi/omap-ssi.txt (limited to 'Documentation/devicetree/bindings/hsi') diff --git a/Documentation/devicetree/bindings/hsi/client-devices.txt b/Documentation/devicetree/bindings/hsi/client-devices.txt new file mode 100644 index 000000000..104c9a3e5 --- /dev/null +++ b/Documentation/devicetree/bindings/hsi/client-devices.txt @@ -0,0 +1,44 @@ +Each HSI port is supposed to have one child node, which +symbols the remote device connected to the HSI port. The +following properties are standardized for HSI clients: + +Required HSI configuration properties: + +- hsi-channel-ids: A list of channel ids + +- hsi-rx-mode: Receiver Bit transmission mode ("stream" or "frame") +- hsi-tx-mode: Transmitter Bit transmission mode ("stream" or "frame") +- hsi-mode: May be used instead hsi-rx-mode and hsi-tx-mode if + the transmission mode is the same for receiver and + transmitter +- hsi-speed-kbps: Max bit transmission speed in kbit/s +- hsi-flow: RX flow type ("synchronized" or "pipeline") +- hsi-arb-mode: Arbitration mode for TX frame ("round-robin", "priority") + +Optional HSI configuration properties: + +- hsi-channel-names: A list with one name per channel specified in the + hsi-channel-ids property + + +Device Tree node example for an HSI client: + +hsi-controller { + hsi-port { + modem: hsi-client { + compatible = "nokia,n900-modem"; + + hsi-channel-ids = <0>, <1>, <2>, <3>; + hsi-channel-names = "mcsaab-control", + "speech-control", + "speech-data", + "mcsaab-data"; + hsi-speed-kbps = <55000>; + hsi-mode = "frame"; + hsi-flow = "synchronized"; + hsi-arb-mode = "round-robin"; + + /* more client specific properties */ + }; + }; +}; diff --git a/Documentation/devicetree/bindings/hsi/nokia-modem.txt b/Documentation/devicetree/bindings/hsi/nokia-modem.txt new file mode 100644 index 000000000..53de1d9d0 --- /dev/null +++ b/Documentation/devicetree/bindings/hsi/nokia-modem.txt @@ -0,0 +1,59 @@ +Nokia modem client bindings + +The Nokia modem HSI client follows the common HSI client binding +and inherits all required properties. The following additional +properties are needed by the Nokia modem HSI client: + +Required properties: +- compatible: Should be one of + "nokia,n900-modem" + "nokia,n950-modem" + "nokia,n9-modem" +- hsi-channel-names: Should contain the following strings + "mcsaab-control" + "speech-control" + "speech-data" + "mcsaab-data" +- gpios: Should provide a GPIO handler for each GPIO listed in + gpio-names +- gpio-names: Should contain the following strings + "cmt_apeslpx" (for n900, n950, n9) + "cmt_rst_rq" (for n900, n950, n9) + "cmt_en" (for n900, n950, n9) + "cmt_rst" (for n900) + "cmt_bsi" (for n900) +- interrupts: Should be IRQ handle for modem's reset indication + +Example: + +&ssi_port { + modem: hsi-client { + compatible = "nokia,n900-modem"; + + pinctrl-names = "default"; + pinctrl-0 = <&modem_pins>; + + hsi-channel-ids = <0>, <1>, <2>, <3>; + hsi-channel-names = "mcsaab-control", + "speech-control", + "speech-data", + "mcsaab-data"; + hsi-speed-kbps = <55000>; + hsi-mode = "frame"; + hsi-flow = "synchronized"; + hsi-arb-mode = "round-robin"; + + interrupts-extended = <&gpio3 8 IRQ_TYPE_EDGE_FALLING>; /* 72 */ + + gpios = <&gpio3 6 GPIO_ACTIVE_HIGH>, /* 70 */ + <&gpio3 9 GPIO_ACTIVE_HIGH>, /* 73 */ + <&gpio3 10 GPIO_ACTIVE_HIGH>, /* 74 */ + <&gpio3 11 GPIO_ACTIVE_HIGH>, /* 75 */ + <&gpio5 29 GPIO_ACTIVE_HIGH>; /* 157 */ + gpio-names = "cmt_apeslpx", + "cmt_rst_rq", + "cmt_en", + "cmt_rst", + "cmt_bsi"; + }; +}; diff --git a/Documentation/devicetree/bindings/hsi/omap-ssi.txt b/Documentation/devicetree/bindings/hsi/omap-ssi.txt new file mode 100644 index 000000000..77a0c3c30 --- /dev/null +++ b/Documentation/devicetree/bindings/hsi/omap-ssi.txt @@ -0,0 +1,102 @@ +OMAP SSI controller bindings + +OMAP3's Synchronous Serial Interface (SSI) controller implements a +legacy variant of MIPI's High Speed Synchronous Serial Interface (HSI), +while the controller found inside OMAP4 is supposed to be fully compliant +with the HSI standard. + +Required properties: +- compatible: Should include "ti,omap3-ssi" or "ti,omap4-hsi" +- reg-names: Contains the values "sys" and "gdd" (in this order). +- reg: Contains a matching register specifier for each entry + in reg-names. +- interrupt-names: Contains the value "gdd_mpu". +- interrupts: Contains matching interrupt information for each entry + in interrupt-names. +- ranges: Represents the bus address mapping between the main + controller node and the child nodes below. +- clock-names: Must include the following entries: + "ssi_ssr_fck": The OMAP clock of that name + "ssi_sst_fck": The OMAP clock of that name + "ssi_ick": The OMAP clock of that name +- clocks: Contains a matching clock specifier for each entry in + clock-names. +- #address-cells: Should be set to <1> +- #size-cells: Should be set to <1> + +Each port is represented as a sub-node of the ti,omap3-ssi device. + +Required Port sub-node properties: +- compatible: Should be set to the following value + ti,omap3-ssi-port (applicable to OMAP34xx devices) + ti,omap4-hsi-port (applicable to OMAP44xx devices) +- reg-names: Contains the values "tx" and "rx" (in this order). +- reg: Contains a matching register specifier for each entry + in reg-names. +- interrupts: Should contain interrupt specifiers for mpu interrupts + 0 and 1 (in this order). +- ti,ssi-cawake-gpio: Defines which GPIO pin is used to signify CAWAKE + events for the port. This is an optional board-specific + property. If it's missing the port will not be + enabled. + +Optional properties: +- ti,hwmods: Shall contain TI interconnect module name if needed + by the SoC + +Example for Nokia N900: + +ssi-controller@48058000 { + compatible = "ti,omap3-ssi"; + + /* needed until hwmod is updated to use the compatible string */ + ti,hwmods = "ssi"; + + reg = <0x48058000 0x1000>, + <0x48059000 0x1000>; + reg-names = "sys", + "gdd"; + + interrupts = <55>; + interrupt-names = "gdd_mpu"; + + clocks = <&ssi_ssr_fck>, + <&ssi_sst_fck>, + <&ssi_ick>; + clock-names = "ssi_ssr_fck", + "ssi_sst_fck", + "ssi_ick"; + + #address-cells = <1>; + #size-cells = <1>; + ranges; + + ssi-port@4805a000 { + compatible = "ti,omap3-ssi-port"; + + reg = <0x4805a000 0x800>, + <0x4805a800 0x800>; + reg-names = "tx", + "rx"; + + interrupt-parent = <&intc>; + interrupts = <67>, + <68>; + + ti,ssi-cawake-gpio = <&gpio5 23 GPIO_ACTIVE_HIGH>; /* 151 */ + } + + ssi-port@4805a000 { + compatible = "ti,omap3-ssi-port"; + + reg = <0x4805b000 0x800>, + <0x4805b800 0x800>; + reg-names = "tx", + "rx"; + + interrupt-parent = <&intc>; + interrupts = <69>, + <70>; + + } +} -- cgit v1.3.1