sched/cache: Keep nr_pref_llc_running in the runnable domain, to fix LLC mis-scheduling buggrafted

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 <zhanxusheng@xiaomi.com>
Suggested-by: Chen Yu <yu.c.chen@intel.com>
Signed-off-by: Tim Chen <tim.c.chen@linux.intel.com>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Signed-off-by: Ingo Molnar <mingo@kernel.org>
Reviewed-by: Kayra Cizmeci <kayracizmeci@gmail.com>
Cc: <stable@kernel.org> # v7.2.x
Link: https://patch.msgid.link/06af61afedac32e6477f57feb4d658f6c411c3af.1790035273.git.tim.c.chen@linux.intel.com

1 files changed, 128 insertions, 0 deletions

diff --git a/include/pcmcia/ciscode.h b/include/pcmcia/ciscode.h
new file mode 100644
index 000000000..a632baff9
--- /dev/null
+++ b/include/pcmcia/ciscode.h
@@ -0,0 +1,128 @@
+/* SPDX-License-Identifier: GPL-2.0-only */
+/*
+ * ciscode.h
+ *
+ * The initial developer of the original code is David A. Hinds
+ * <dahinds@users.sourceforge.net>.  Portions created by David A. Hinds
+ * are Copyright (C) 1999 David A. Hinds.  All Rights Reserved.
+ *
+ * (C) 1999		David A. Hinds
+ */
+
+#ifndef _LINUX_CISCODE_H
+#define _LINUX_CISCODE_H
+
+/* Manufacturer and Product ID codes */
+
+#define MANFID_3COM			0x0101
+#define PRODID_3COM_3CXEM556		0x0035
+#define PRODID_3COM_3CCFEM556		0x0556
+#define PRODID_3COM_3C562		0x0562
+
+#define MANFID_ACCTON			0x01bf
+#define PRODID_ACCTON_EN2226		0x010a
+
+#define MANFID_ADAPTEC			0x012f
+#define PRODID_ADAPTEC_SCSI		0x0001
+
+#define MANFID_ATT			0xffff
+#define PRODID_ATT_KIT			0x0100
+
+#define MANFID_CONTEC			0xc001
+
+#define MANFID_FUJITSU			0x0004
+#define PRODID_FUJITSU_MBH10302		0x0004
+#define PRODID_FUJITSU_MBH10304		0x1003
+#define PRODID_FUJITSU_LA501		0x2000
+
+#define MANFID_IBM			0x00a4
+#define PRODID_IBM_HOME_AND_AWAY	0x002e
+
+#define MANFID_INTEL			0x0089
+#define PRODID_INTEL_DUAL_RS232		0x0301
+#define PRODID_INTEL_2PLUS		0x8422
+
+#define MANFID_KME			0x0032
+#define PRODID_KME_KXLC005_A		0x0704
+#define PRODID_KME_KXLC005_B		0x2904
+
+#define MANFID_LINKSYS			0x0143
+#define PRODID_LINKSYS_PCMLM28		0xc0ab
+#define PRODID_LINKSYS_3400		0x3341
+
+#define MANFID_MEGAHERTZ		0x0102
+#define PRODID_MEGAHERTZ_VARIOUS	0x0000
+#define PRODID_MEGAHERTZ_EM3288		0x0006
+
+#define MANFID_MACNICA			0xc00b
+
+#define MANFID_MOTOROLA			0x0109
+#define PRODID_MOTOROLA_MARINER		0x0501
+
+#define MANFID_NATINST			0x010b
+#define PRODID_NATINST_QUAD_RS232	0xd180
+
+#define MANFID_NEW_MEDIA		0x0057
+
+#define MANFID_NOKIA			0x0124
+#define PRODID_NOKIA_CARDPHONE		0x0900
+
+#define MANFID_OLICOM			0x0121
+#define PRODID_OLICOM_OC2231		0x3122
+#define PRODID_OLICOM_OC2232		0x3222
+
+#define MANFID_OMEGA			0x0137
+#define PRODID_OMEGA_QSP_100		0x0025
+
+#define MANFID_OSITECH			0x0140
+#define PRODID_OSITECH_JACK_144		0x0001
+#define PRODID_OSITECH_JACK_288		0x0002
+#define PRODID_OSITECH_JACK_336		0x0007
+#define PRODID_OSITECH_SEVEN		0x0008
+
+#define MANFID_OXSEMI			0x0279
+
+#define MANFID_PIONEER			0x000b
+
+#define MANFID_PSION			0x016c
+#define PRODID_PSION_NET100		0x0023
+
+#define MANFID_QUATECH			0x0137
+#define PRODID_QUATECH_SPP100		0x0003
+#define PRODID_QUATECH_DUAL_RS232	0x0012
+#define PRODID_QUATECH_DUAL_RS232_D1	0x0007
+#define PRODID_QUATECH_DUAL_RS232_D2	0x0052
+#define PRODID_QUATECH_DUAL_RS232_G	0x004d
+#define PRODID_QUATECH_QUAD_RS232	0x001b
+#define PRODID_QUATECH_DUAL_RS422	0x000e
+#define PRODID_QUATECH_QUAD_RS422	0x0045
+
+#define MANFID_SMC			0x0108
+#define PRODID_SMC_ETHER		0x0105
+
+#define MANFID_SOCKET			0x0104
+#define PRODID_SOCKET_DUAL_RS232	0x0006
+#define PRODID_SOCKET_EIO		0x000a
+#define PRODID_SOCKET_LPE		0x000d
+#define PRODID_SOCKET_LPE_CF		0x0075
+
+#define MANFID_SUNDISK			0x0045
+
+#define MANFID_TDK			0x0105
+#define PRODID_TDK_CF010		0x0900
+#define PRODID_TDK_NP9610		0x0d0a
+#define PRODID_TDK_MN3200		0x0e0a
+#define PRODID_TDK_GN3410		0x4815
+
+#define MANFID_TOSHIBA			0x0098
+
+#define MANFID_UNGERMANN		0x02c0
+
+#define MANFID_XIRCOM			0x0105
+
+#define MANFID_POSSIO			0x030c
+#define PRODID_POSSIO_GCC		0x0003
+
+#define MANFID_NEC			0x0010
+
+#endif /* _LINUX_CISCODE_H */