mm: disable NUMA_BALANCING_DEFAULT_ENABLED and TRANSPARENT_HUGEPAGE on PREEMPT_RT

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>

diff --git a/init/Kconfig b/init/Kconfig
index 11f8a845f259da63299a77001991631be81c0eac..21b1f4870c807fc69ed2872a1a93b1d705d46cd7 100644 (file)
--- 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 d16ba9249bc531bd34d6a5e0e85c83e84f19fcf1..9f1e0098522c26c02f3642a75662b36d1e1b5d22 100644 (file)
--- 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