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/mm/cache.c | 218 +++++++++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 218 insertions(+) create mode 100644 arch/mips/mm/cache.c (limited to 'arch/mips/mm/cache.c') diff --git a/arch/mips/mm/cache.c b/arch/mips/mm/cache.c new file mode 100644 index 000000000..ad9b0430a --- /dev/null +++ b/arch/mips/mm/cache.c @@ -0,0 +1,218 @@ +/* + * This file is subject to the terms and conditions of the GNU General Public + * License. See the file "COPYING" in the main directory of this archive + * for more details. + * + * Copyright (C) 1994 - 2003, 06, 07 by Ralf Baechle (ralf@linux-mips.org) + * Copyright (C) 2007 MIPS Technologies, Inc. + */ +#include +#include +#include +#include +#include +#include +#include +#include +#include +#include + +#include +#include +#include +#include +#include +#include +#include + +/* Cache operations. */ +void (*flush_cache_all)(void); +void (*__flush_cache_all)(void); +EXPORT_SYMBOL_GPL(__flush_cache_all); +void (*flush_cache_mm)(struct mm_struct *mm); +void (*flush_cache_range)(struct vm_area_struct *vma, unsigned long start, + unsigned long end); +void (*flush_cache_page)(struct vm_area_struct *vma, unsigned long page, + unsigned long pfn); +void (*flush_icache_range)(unsigned long start, unsigned long end); +EXPORT_SYMBOL_GPL(flush_icache_range); +void (*local_flush_icache_range)(unsigned long start, unsigned long end); +EXPORT_SYMBOL_GPL(local_flush_icache_range); +void (*__flush_icache_user_range)(unsigned long start, unsigned long end); +void (*__local_flush_icache_user_range)(unsigned long start, unsigned long end); +EXPORT_SYMBOL_GPL(__local_flush_icache_user_range); + +void (*__flush_cache_vmap)(void); +void (*__flush_cache_vunmap)(void); + +void (*__flush_kernel_vmap_range)(unsigned long vaddr, int size); +EXPORT_SYMBOL_GPL(__flush_kernel_vmap_range); + +/* MIPS specific cache operations */ +void (*flush_data_cache_page)(unsigned long addr); +void (*flush_icache_all)(void); + +EXPORT_SYMBOL(flush_data_cache_page); +EXPORT_SYMBOL(flush_icache_all); + +/* + * Dummy cache handling routine + */ + +void cache_noop(void) {} + +#ifdef CONFIG_BOARD_SCACHE + +static struct bcache_ops no_sc_ops = { + .bc_enable = (void *)cache_noop, + .bc_disable = (void *)cache_noop, + .bc_wback_inv = (void *)cache_noop, + .bc_inv = (void *)cache_noop +}; + +struct bcache_ops *bcops = &no_sc_ops; +#endif + +#ifdef CONFIG_DMA_NONCOHERENT + +/* DMA cache operations. */ +void (*_dma_cache_wback_inv)(unsigned long start, unsigned long size); +void (*_dma_cache_wback)(unsigned long start, unsigned long size); +void (*_dma_cache_inv)(unsigned long start, unsigned long size); + +#endif /* CONFIG_DMA_NONCOHERENT */ + +/* + * We could optimize the case where the cache argument is not BCACHE but + * that seems very atypical use ... + */ +SYSCALL_DEFINE3(cacheflush, unsigned long, addr, unsigned long, bytes, + unsigned int, cache) +{ + if (bytes == 0) + return 0; + if (!access_ok((void __user *) addr, bytes)) + return -EFAULT; + + __flush_icache_user_range(addr, addr + bytes); + + return 0; +} + +void __flush_dcache_folio_pages(struct folio *folio, struct page *page, + unsigned int nr) +{ + struct address_space *mapping = folio_flush_mapping(folio); + unsigned long addr; + unsigned int i; + + if (mapping && !mapping_mapped(mapping)) { + folio_set_dcache_dirty(folio); + return; + } + + /* + * We could delay the flush for the !folio_mapping case too. But that + * case is for exec env/arg pages and those are %99 certainly going to + * get faulted into the tlb (and thus flushed) anyways. + */ + for (i = 0; i < nr; i++) { + addr = (unsigned long)kmap_local_page(page + i); + flush_data_cache_page(addr); + kunmap_local((void *)addr); + } +} +EXPORT_SYMBOL(__flush_dcache_folio_pages); + +void __flush_anon_page(struct page *page, unsigned long vmaddr) +{ + unsigned long addr = (unsigned long) page_address(page); + struct folio *folio = page_folio(page); + + if (pages_do_alias(addr, vmaddr)) { + if (folio_mapped(folio) && !folio_test_dcache_dirty(folio)) { + void *kaddr; + + kaddr = kmap_coherent(page, vmaddr); + flush_data_cache_page((unsigned long)kaddr); + kunmap_coherent(); + } else + flush_data_cache_page(addr); + } +} + +EXPORT_SYMBOL(__flush_anon_page); + +void __update_cache(unsigned long address, pte_t pte) +{ + struct folio *folio; + unsigned long pfn, addr; + int exec = !pte_no_exec(pte) && !cpu_has_ic_fills_f_dc; + unsigned int i; + + pfn = pte_pfn(pte); + if (unlikely(!pfn_valid(pfn))) + return; + + folio = page_folio(pfn_to_page(pfn)); + address &= PAGE_MASK; + address -= offset_in_folio(folio, pfn << PAGE_SHIFT); + + if (folio_test_dcache_dirty(folio)) { + for (i = 0; i < folio_nr_pages(folio); i++) { + addr = (unsigned long)kmap_local_folio(folio, i); + + if (exec || pages_do_alias(addr, address)) + flush_data_cache_page(addr); + kunmap_local((void *)addr); + address += PAGE_SIZE; + } + folio_clear_dcache_dirty(folio); + } +} + +unsigned long _page_cachable_default; +EXPORT_SYMBOL(_page_cachable_default); + +#define PM(p) __pgprot(_page_cachable_default | (p)) + +static pgprot_t protection_map[16] __ro_after_init; +DECLARE_VM_GET_PAGE_PROT + +static inline void setup_protection_map(void) +{ + protection_map[0] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); + protection_map[1] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[2] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); + protection_map[3] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[4] = PM(_PAGE_PRESENT); + protection_map[5] = PM(_PAGE_PRESENT); + protection_map[6] = PM(_PAGE_PRESENT); + protection_map[7] = PM(_PAGE_PRESENT); + + protection_map[8] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_NO_READ); + protection_map[9] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC); + protection_map[10] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE | + _PAGE_NO_READ); + protection_map[11] = PM(_PAGE_PRESENT | _PAGE_NO_EXEC | _PAGE_WRITE); + protection_map[12] = PM(_PAGE_PRESENT); + protection_map[13] = PM(_PAGE_PRESENT); + protection_map[14] = PM(_PAGE_PRESENT | _PAGE_WRITE); + protection_map[15] = PM(_PAGE_PRESENT | _PAGE_WRITE); +} + +#undef PM + +void cpu_cache_init(void) +{ + if (IS_ENABLED(CONFIG_CPU_R3000) && cpu_has_3k_cache) + r3k_cache_init(); + if ((IS_ENABLED(CONFIG_CPU_R4K_CACHE_TLB) || + IS_ENABLED(CONFIG_CPU_SB1)) && cpu_has_4k_cache) + r4k_cache_init(); + + if (IS_ENABLED(CONFIG_CPU_CAVIUM_OCTEON) && cpu_has_octeon_cache) + octeon_cache_init(); + + setup_protection_map(); +} -- cgit v1.3.1