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/mips/rb532/setup.c | 81 +++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 81 insertions(+) create mode 100644 arch/mips/rb532/setup.c (limited to 'arch/mips/rb532/setup.c') diff --git a/arch/mips/rb532/setup.c b/arch/mips/rb532/setup.c new file mode 100644 index 000000000..51af9d374 --- /dev/null +++ b/arch/mips/rb532/setup.c @@ -0,0 +1,81 @@ +// SPDX-License-Identifier: GPL-2.0 +/* + * setup.c - boot time setup code + */ + +#include +#include + +#include +#include +#include +#include + +#include +#include + +struct pci_reg __iomem *pci_reg; +EXPORT_SYMBOL(pci_reg); + +static struct resource pci0_res[] = { + { + .name = "pci_reg0", + .start = PCI0_BASE_ADDR, + .end = PCI0_BASE_ADDR + sizeof(struct pci_reg), + .flags = IORESOURCE_MEM, + } +}; + +static void rb_machine_restart(char *command) +{ + /* just jump to the reset vector */ + writel(0x80000001, IDT434_REG_BASE + RST); + ((void (*)(void)) KSEG1ADDR(0x1FC00000u))(); +} + +static void rb_machine_halt(void) +{ + for (;;) + continue; +} + +void __init plat_mem_setup(void) +{ + u32 val; + + _machine_restart = rb_machine_restart; + _machine_halt = rb_machine_halt; + pm_power_off = rb_machine_halt; + + set_io_port_base(KSEG1); + + pci_reg = ioremap(pci0_res[0].start, + pci0_res[0].end - pci0_res[0].start); + if (!pci_reg) { + printk(KERN_ERR "Could not remap PCI registers\n"); + return; + } + + val = __raw_readl(&pci_reg->pcic); + val &= 0xFFFFFF7; + __raw_writel(val, (void *)&pci_reg->pcic); + +#ifdef CONFIG_PCI + /* Enable PCI interrupts in EPLD Mask register */ + *epld_mask = 0x0; + *(epld_mask + 1) = 0x0; +#endif + write_c0_wired(0); +} + +const char *get_system_type(void) +{ + switch (mips_machtype) { + case MACH_MIKROTIK_RB532A: + return "Mikrotik RB532A"; + break; + default: + return "Mikrotik RB532"; + break; + } +} -- cgit v1.3.1