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/input/tablet/Kconfig | 90 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 90 insertions(+) create mode 100644 drivers/input/tablet/Kconfig (limited to 'drivers/input/tablet/Kconfig') diff --git a/drivers/input/tablet/Kconfig b/drivers/input/tablet/Kconfig new file mode 100644 index 000000000..ec27eff6a --- /dev/null +++ b/drivers/input/tablet/Kconfig @@ -0,0 +1,90 @@ +# SPDX-License-Identifier: GPL-2.0-only +# +# Tablet driver configuration +# +menuconfig INPUT_TABLET + bool "Tablets" + help + Say Y here, and a list of supported tablets will be displayed. + This option doesn't affect the kernel. + + If unsure, say Y. + +if INPUT_TABLET + +config TABLET_USB_ACECAD + tristate "Acecad Flair tablet support (USB)" + depends on USB_ARCH_HAS_HCD + select USB + help + Say Y here if you want to use the USB version of the Acecad Flair + tablet. Make sure to say Y to "Mouse support" + (CONFIG_INPUT_MOUSEDEV) and/or "Event interface support" + (CONFIG_INPUT_EVDEV) as well. + + To compile this driver as a module, choose M here: the + module will be called acecad. + +config TABLET_USB_AIPTEK + tristate "Aiptek 6000U/8000U and Genius G_PEN tablet support (USB)" + depends on USB_ARCH_HAS_HCD + select USB + help + Say Y here if you want to use the USB version of the Aiptek 6000U, + Aiptek 8000U or Genius G-PEN 560 tablet. Make sure to say Y to + "Mouse support" (CONFIG_INPUT_MOUSEDEV) and/or "Event interface + support" (CONFIG_INPUT_EVDEV) as well. + + To compile this driver as a module, choose M here: the + module will be called aiptek. + +config TABLET_USB_HANWANG + tristate "Hanwang Art Master III tablet support (USB)" + depends on USB_ARCH_HAS_HCD + select USB + help + Say Y here if you want to use the USB version of the Hanwang Art + Master III tablet. + + To compile this driver as a module, choose M here: the + module will be called hanwang. + +config TABLET_USB_KBTAB + tristate "KB Gear JamStudio tablet support (USB)" + depends on USB_ARCH_HAS_HCD + select USB + help + Say Y here if you want to use the USB version of the KB Gear + JamStudio tablet. Make sure to say Y to "Mouse support" + (CONFIG_INPUT_MOUSEDEV) and/or "Event interface support" + (CONFIG_INPUT_EVDEV) as well. + + To compile this driver as a module, choose M here: the + module will be called kbtab. + +config TABLET_USB_PEGASUS + tristate "Pegasus Mobile Notetaker Pen input tablet support" + depends on USB_ARCH_HAS_HCD + select USB + help + Say Y here if you want to use the Pegasus Mobile Notetaker, + also known as: + Genie e-note The Notetaker, + Staedtler Digital ballpoint pen 990 01, + IRISnotes Express or + NEWLink Digital Note Taker. + + To compile this driver as a module, choose M here: the + module will be called pegasus_notetaker. + +config TABLET_SERIAL_WACOM4 + tristate "Wacom protocol 4 serial tablet support" + select SERIO + help + Say Y here if you want to use Wacom protocol 4 serial tablets. + E.g. serial versions of the Cintiq, Graphire or Penpartner. + + To compile this driver as a module, choose M here: the + module will be called wacom_serial4. + +endif -- cgit v1.3.1