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 --- drivers/iommu/Makefile | 40 ++++++++++++++++++++++++++++++++++++++++ 1 file changed, 40 insertions(+) create mode 100644 drivers/iommu/Makefile (limited to 'drivers/iommu/Makefile') diff --git a/drivers/iommu/Makefile b/drivers/iommu/Makefile new file mode 100644 index 000000000..2f05725ea --- /dev/null +++ b/drivers/iommu/Makefile @@ -0,0 +1,40 @@ +# SPDX-License-Identifier: GPL-2.0 +obj-y += arm/ iommufd/ +obj-$(CONFIG_AMD_IOMMU) += amd/ +obj-$(CONFIG_INTEL_IOMMU) += intel/ +obj-$(CONFIG_RISCV_IOMMU) += riscv/ +obj-$(CONFIG_GENERIC_PT) += generic_pt/fmt/ +obj-$(CONFIG_HYPERV) += hyperv/ +obj-$(CONFIG_IOMMU_API) += iommu.o +obj-$(CONFIG_IOMMU_SUPPORT) += iommu-pages.o +obj-$(CONFIG_IOMMU_API) += iommu-traces.o +obj-$(CONFIG_IOMMU_API) += iommu-sysfs.o +obj-$(CONFIG_IOMMU_DEBUGFS) += iommu-debugfs.o +obj-$(CONFIG_IOMMU_DMA) += dma-iommu.o +obj-$(CONFIG_IOMMU_IO_PGTABLE) += io-pgtable.o +obj-$(CONFIG_IOMMU_IO_PGTABLE_ARMV7S) += io-pgtable-arm-v7s.o +obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE) += io-pgtable-arm.o +obj-$(CONFIG_IOMMU_IO_PGTABLE_LPAE_KUNIT_TEST) += io-pgtable-arm-selftests.o +obj-$(CONFIG_IOMMU_IO_PGTABLE_DART) += io-pgtable-dart.o +obj-$(CONFIG_IOMMU_IOVA) += iova.o +obj-$(CONFIG_OF_IOMMU) += of_iommu.o +obj-$(CONFIG_MSM_IOMMU) += msm_iommu.o +obj-$(CONFIG_IPMMU_VMSA) += ipmmu-vmsa.o +obj-$(CONFIG_IRQ_REMAP) += irq_remapping.o +obj-$(CONFIG_MTK_IOMMU) += mtk_iommu.o +obj-$(CONFIG_MTK_IOMMU_V1) += mtk_iommu_v1.o +obj-$(CONFIG_OMAP_IOMMU) += omap-iommu.o +obj-$(CONFIG_OMAP_IOMMU_DEBUG) += omap-iommu-debug.o +obj-$(CONFIG_ROCKCHIP_IOMMU) += rockchip-iommu.o +obj-$(CONFIG_SUN50I_IOMMU) += sun50i-iommu.o +obj-$(CONFIG_TEGRA_IOMMU_SMMU) += tegra-smmu.o +obj-$(CONFIG_EXYNOS_IOMMU) += exynos-iommu.o +obj-$(CONFIG_FSL_PAMU) += fsl_pamu.o fsl_pamu_domain.o +obj-$(CONFIG_S390_IOMMU) += s390-iommu.o +obj-$(CONFIG_VIRTIO_IOMMU) += virtio-iommu.o +obj-$(CONFIG_IOMMU_SVA) += iommu-sva.o +obj-$(CONFIG_IOMMU_IOPF) += io-pgfault.o +obj-$(CONFIG_SPRD_IOMMU) += sprd-iommu.o +obj-$(CONFIG_APPLE_DART) += apple-dart.o +obj-$(CONFIG_VSI_IOMMU) += vsi-iommu.o +obj-$(CONFIG_IOMMU_DEBUG_PAGEALLOC) += iommu-debug-pagealloc.o -- cgit v1.3.1