1 files changed, 55 insertions, 0 deletions
diff --git a/debian/patches-rt/mm-compaction-Disable-compact_unevictable_allowed-on.patch b/debian/patches-rt/mm-compaction-Disable-compact_unevictable_allowed-on.patch
new file mode 100644
index 000000000..d30468f92
--- /dev/null
+++ b/debian/patches-rt/mm-compaction-Disable-compact_unevictable_allowed-on.patch
@@ -0,0 +1,55 @@
+From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+Date: Fri, 8 Nov 2019 12:55:47 +0100
+Subject: [PATCH] mm/compaction: Disable compact_unevictable_allowed on RT
+Origin: https://www.kernel.org/pub/linux/kernel/projects/rt/5.4/older/patches-5.4.3-rt1.tar.xz
+
+Since commit
+    5bbe3547aa3ba ("mm: allow compaction of unevictable pages")
+
+it is allowed to examine mlocked pages for pages to compact by default.
+On -RT even minor pagefaults are problematic because it may take a few
+100us to resolve them and until then the task is blocked.
+
+Make compact_unevictable_allowed = 0 default and remove it from /proc on
+RT.
+
+Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@linutronix.de/
+Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
+---
+ kernel/sysctl.c |    3 ++-
+ mm/compaction.c |    4 ++++
+ 2 files changed, 6 insertions(+), 1 deletion(-)
+
+--- a/kernel/sysctl.c
++++ b/kernel/sysctl.c
+@@ -1488,6 +1488,7 @@ static struct ctl_table vm_table[] = {
+ 		.extra1		= &min_extfrag_threshold,
+ 		.extra2		= &max_extfrag_threshold,
+ 	},
++#ifndef CONFIG_PREEMPT_RT
+ 	{
+ 		.procname	= "compact_unevictable_allowed",
+ 		.data		= &sysctl_compact_unevictable_allowed,
+@@ -1497,7 +1498,7 @@ static struct ctl_table vm_table[] = {
+ 		.extra1		= SYSCTL_ZERO,
+ 		.extra2		= SYSCTL_ONE,
+ 	},
+-
++#endif
+ #endif /* CONFIG_COMPACTION */
+ 	{
+ 		.procname	= "min_free_kbytes",
+--- a/mm/compaction.c
++++ b/mm/compaction.c
+@@ -1590,7 +1590,11 @@ typedef enum {
+  * Allow userspace to control policy on scanning the unevictable LRU for
+  * compactable pages.
+  */
++#ifdef CONFIG_PREEMPT_RT
++#define sysctl_compact_unevictable_allowed 0
++#else
+ int sysctl_compact_unevictable_allowed __read_mostly = 1;
++#endif
+ 
+ static inline void
+ update_fast_start_pfn(struct compact_control *cc, unsigned long pfn)