From 554b0f3ca6f4948fdbab5f199858d902061318d0 Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Fri, 5 Nov 2021 13:35:27 -0700
Subject: [PATCH] mm: disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT
Git-commit: 554b0f3ca6f4948fdbab5f199858d902061318d0
Patch-mainline: v5.16-rc1
References: bsc#1189998
Transparent_hugepage: There are potential non-deterministic delays to an RT thread if a
critical memory region is not THP-aligned and a non-RT buffer is
located in the same hugepage-aligned region. It's also possible for an
unrelated thread to migrate pages belonging to an RT task incurring
unexpected page faults due to memory defragmentation even if
khugepaged is disabled.
Regular HUGEPAGEs are not affected by this can be used.
Numa_balancing: There is a non-deterministic delay to mark PTEs PROT_NONE to gather
NUMA fault samples, increased page faults of regions even if mlocked
and non-deterministic delays when migrating pages.
[Mel Gorman worded 99% of the commit description].
Link: https://lore.kernel.org/all/20200304091159.GN3818@techsingularity.net/
Link: https://lore.kernel.org/all/20211026165100.ahz5bkx44lrrw5pt@linutronix.de/
Link: https://lkml.kernel.org/r/20211028143327.hfbxjze7palrpfgp@linutronix.de
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Acked-by: Mel Gorman <mgorman@techsingularity.net>
Reviewed-by: David Hildenbrand <david@redhat.com>
Cc: Vlastimil Babka <vbabka@suse.cz>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Thomas Gleixner <tglx@linutronix.de>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Davidlohr Bueso <dbueso@suse.de>
---
init/Kconfig | 2 +-
mm/Kconfig | 2 +-
2 files changed, 2 insertions(+), 2 deletions(-)
diff --git a/init/Kconfig b/init/Kconfig
index 11f8a845f259..21b1f4870c80 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -901,7 +901,7 @@ config NUMA_BALANCING
bool "Memory placement aware NUMA scheduler"
depends on ARCH_SUPPORTS_NUMA_BALANCING
depends on !ARCH_WANT_NUMA_VARIABLE_LOCALITY
- depends on SMP && NUMA && MIGRATION
+ depends on SMP && NUMA && MIGRATION && !PREEMPT_RT
help
This option adds support for automatic NUMA aware memory/task placement.
The mechanism is quite primitive and is based on migrating memory when
diff --git a/mm/Kconfig b/mm/Kconfig
index d16ba9249bc5..9f1e0098522c 100644
--- a/mm/Kconfig
+++ b/mm/Kconfig
@@ -371,7 +371,7 @@ config NOMMU_INITIAL_TRIM_EXCESS
config TRANSPARENT_HUGEPAGE
bool "Transparent Hugepage Support"
- depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE
+ depends on HAVE_ARCH_TRANSPARENT_HUGEPAGE && !PREEMPT_RT
select COMPACTION
select XARRAY_MULTI
help
--
2.26.2