The patch titled
Subject: mm/compaction: disable compact_unevictable_allowed on RT
has been removed from the -mm tree. Its filename was
mm-compaction-disable-compact_unevictable_allowed-on-rt.patch
This patch was dropped because an updated version will be merged
------------------------------------------------------
From: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Subject: mm/compaction: disable compact_unevictable_allowed on RT
Since commit 5bbe3547aa3ba ("mm: allow compaction of unevictable pages")
it is allowed to examine mlocked pages and compact them 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 RO on RT.
Link: https://lore.kernel.org/linux-mm/20190710144138.qyn4tuttdq6h7kqx@xxxxxxxxxxxxx/
Link: http://lkml.kernel.org/r/20200302173516.iysuejilava37psk@xxxxxxxxxxxxx
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@xxxxxxxxxxxxx>
Cc: Thomas Gleixner <tglx@xxxxxxxxxxxxx>
Cc: Luis Chamberlain <mcgrof@xxxxxxxxxx>
Cc: Kees Cook <keescook@xxxxxxxxxxxx>
Cc: Iurii Zaikin <yzaikin@xxxxxxxxxx>
Cc: Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx>
Signed-off-by: Andrew Morton <akpm@xxxxxxxxxxxxxxxxxxxx>
---
Documentation/admin-guide/sysctl/vm.rst | 1 +
kernel/sysctl.c | 4 ++++
mm/compaction.c | 4 ++++
3 files changed, 9 insertions(+)
--- a/Documentation/admin-guide/sysctl/vm.rst~mm-compaction-disable-compact_unevictable_allowed-on-rt
+++ a/Documentation/admin-guide/sysctl/vm.rst
@@ -128,6 +128,7 @@ allowed to examine the unevictable lru (
This should be used on systems where stalls for minor page faults are an
acceptable trade for large contiguous free memory. Set to 0 to prevent
compaction from moving pages that are unevictable. Default value is 1.
+On CONFIG_PREEMPT_RT the default value is 0.
dirty_background_bytes
--- a/kernel/sysctl.c~mm-compaction-disable-compact_unevictable_allowed-on-rt
+++ a/kernel/sysctl.c
@@ -1483,7 +1483,11 @@ static struct ctl_table vm_table[] = {
.procname = "compact_unevictable_allowed",
.data = &sysctl_compact_unevictable_allowed,
.maxlen = sizeof(int),
+#ifdef CONFIG_PREEMPT_RT
+ .mode = 0444,
+#else
.mode = 0644,
+#endif
.proc_handler = proc_dointvec,
.extra1 = SYSCTL_ZERO,
.extra2 = SYSCTL_ONE,
--- a/mm/compaction.c~mm-compaction-disable-compact_unevictable_allowed-on-rt
+++ a/mm/compaction.c
@@ -1594,7 +1594,11 @@ typedef enum {
* Allow userspace to control policy on scanning the unevictable LRU for
* compactable pages.
*/
+#ifdef CONFIG_PREEMPT_RT
+int sysctl_compact_unevictable_allowed __read_mostly = 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)
_
Patches currently in -mm which might be from bigeasy@xxxxxxxxxxxxx are
mm-z3fold-do-not-include-rwlockh-directly.patch
really-limit-compact_unevictable_allowed-to-0-and-1.patch
