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 --- arch/arm/mach-omap1/timer.c | 165 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 165 insertions(+) create mode 100644 arch/arm/mach-omap1/timer.c (limited to 'arch/arm/mach-omap1/timer.c') diff --git a/arch/arm/mach-omap1/timer.c b/arch/arm/mach-omap1/timer.c new file mode 100644 index 000000000..399e6d840 --- /dev/null +++ b/arch/arm/mach-omap1/timer.c @@ -0,0 +1,165 @@ +// SPDX-License-Identifier: GPL-2.0-only +/* + * OMAP1 Dual-Mode Timers - platform device registration + * + * Contains first level initialization routines which internally + * generates timer device information and registers with linux + * device model. It also has a low level function to change the timer + * input clock source. + * + * Copyright (C) 2011 Texas Instruments Incorporated - https://www.ti.com/ + * Tarun Kanti DebBarma + * Thara Gopinath + */ + +#include +#include +#include +#include +#include +#include +#include + +#include + +#include "soc.h" + +#define OMAP1610_GPTIMER1_BASE 0xfffb1400 +#define OMAP1610_GPTIMER2_BASE 0xfffb1c00 +#define OMAP1610_GPTIMER3_BASE 0xfffb2400 +#define OMAP1610_GPTIMER4_BASE 0xfffb2c00 +#define OMAP1610_GPTIMER5_BASE 0xfffb3400 +#define OMAP1610_GPTIMER6_BASE 0xfffb3c00 +#define OMAP1610_GPTIMER7_BASE 0xfffb7400 +#define OMAP1610_GPTIMER8_BASE 0xfffbd400 + +#define OMAP1_DM_TIMER_COUNT 8 + +static int omap1_dm_timer_set_src(struct platform_device *pdev, + int source) +{ + int n = (pdev->id - 1) << 1; + u32 l; + + l = omap_readl(MOD_CONF_CTRL_1) & ~(0x03 << n); + l |= source << n; + omap_writel(l, MOD_CONF_CTRL_1); + + return 0; +} + +static int __init omap1_dm_timer_init(void) +{ + int i; + int ret; + struct dmtimer_platform_data *pdata; + struct platform_device *pdev; + + if (!cpu_is_omap16xx()) + return 0; + + for (i = 1; i <= OMAP1_DM_TIMER_COUNT; i++) { + struct resource res[2]; + u32 base, irq; + + switch (i) { + case 1: + base = OMAP1610_GPTIMER1_BASE; + irq = INT_1610_GPTIMER1; + break; + case 2: + base = OMAP1610_GPTIMER2_BASE; + irq = INT_1610_GPTIMER2; + break; + case 3: + base = OMAP1610_GPTIMER3_BASE; + irq = INT_1610_GPTIMER3; + break; + case 4: + base = OMAP1610_GPTIMER4_BASE; + irq = INT_1610_GPTIMER4; + break; + case 5: + base = OMAP1610_GPTIMER5_BASE; + irq = INT_1610_GPTIMER5; + break; + case 6: + base = OMAP1610_GPTIMER6_BASE; + irq = INT_1610_GPTIMER6; + break; + case 7: + base = OMAP1610_GPTIMER7_BASE; + irq = INT_1610_GPTIMER7; + break; + case 8: + base = OMAP1610_GPTIMER8_BASE; + irq = INT_1610_GPTIMER8; + break; + default: + /* + * not supposed to reach here. + * this is to remove warning. + */ + return -EINVAL; + } + + pdev = platform_device_alloc("omap_timer", i); + if (!pdev) { + pr_err("%s: Failed to device alloc for dmtimer%d\n", + __func__, i); + return -ENOMEM; + } + + memset(res, 0, 2 * sizeof(struct resource)); + res[0].start = base; + res[0].end = base + 0x46; + res[0].flags = IORESOURCE_MEM; + res[1].start = irq; + res[1].end = irq; + res[1].flags = IORESOURCE_IRQ; + ret = platform_device_add_resources(pdev, res, + ARRAY_SIZE(res)); + if (ret) { + dev_err(&pdev->dev, "%s: Failed to add resources.\n", + __func__); + goto err_free_pdev; + } + + pdata = kzalloc_obj(*pdata); + if (!pdata) { + ret = -ENOMEM; + goto err_free_pdata; + } + + pdata->set_timer_src = omap1_dm_timer_set_src; + pdata->timer_capability = OMAP_TIMER_ALWON | + OMAP_TIMER_NEEDS_RESET | OMAP_TIMER_HAS_DSP_IRQ; + + ret = platform_device_add_data(pdev, pdata, sizeof(*pdata)); + if (ret) { + dev_err(&pdev->dev, "%s: Failed to add platform data.\n", + __func__); + goto err_free_pdata; + } + + ret = platform_device_add(pdev); + if (ret) { + dev_err(&pdev->dev, "%s: Failed to add platform device.\n", + __func__); + goto err_free_pdata; + } + + dev_dbg(&pdev->dev, " Registered.\n"); + } + + return 0; + +err_free_pdata: + kfree(pdata); + +err_free_pdev: + platform_device_put(pdev); + + return ret; +} +arch_initcall(omap1_dm_timer_init); -- cgit v1.3.1