5.4-stable patches

added patches:
	sched-rt-disable-rt_runtime_share-by-default.patch

diff --git a/queue-5.4/sched-rt-disable-rt_runtime_share-by-default.patch b/queue-5.4/sched-rt-disable-rt_runtime_share-by-default.patch
new file mode 100644 (file)
index 0000000..1999477
--- /dev/null
+++ b/queue-5.4/sched-rt-disable-rt_runtime_share-by-default.patch
@@ -0,0 +1,43 @@
+From 2586af1ac187f6b3a50930a4e33497074e81762d Mon Sep 17 00:00:00 2001
+From: Daniel Bristot de Oliveira <bristot@redhat.com>
+Date: Mon, 21 Sep 2020 16:39:49 +0200
+Subject: sched/rt: Disable RT_RUNTIME_SHARE by default
+
+From: Daniel Bristot de Oliveira <bristot@redhat.com>
+
+commit 2586af1ac187f6b3a50930a4e33497074e81762d upstream.
+
+The RT_RUNTIME_SHARE sched feature enables the sharing of rt_runtime
+between CPUs, allowing a CPU to run a real-time task up to 100% of the
+time while leaving more space for non-real-time tasks to run on the CPU
+that lend rt_runtime.
+
+The problem is that a CPU can easily borrow enough rt_runtime to allow
+a spinning rt-task to run forever, starving per-cpu tasks like kworkers,
+which are non-real-time by design.
+
+This patch disables RT_RUNTIME_SHARE by default, avoiding this problem.
+The feature will still be present for users that want to enable it,
+though.
+
+Signed-off-by: Daniel Bristot de Oliveira <bristot@redhat.com>
+Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
+Tested-by: Wei Wang <wvw@google.com>
+Link: https://lkml.kernel.org/r/b776ab46817e3db5d8ef79175fa0d71073c051c7.1600697903.git.bristot@redhat.com
+Signed-off-by: Mark-PK Tsai <mark-pk.tsai@mediatek.com>
+Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
+---
+ kernel/sched/features.h |    2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+--- a/kernel/sched/features.h
++++ b/kernel/sched/features.h
+@@ -77,7 +77,7 @@ SCHED_FEAT(WARN_DOUBLE_CLOCK, false)
+ SCHED_FEAT(RT_PUSH_IPI, true)
+ #endif
+ 
+-SCHED_FEAT(RT_RUNTIME_SHARE, true)
++SCHED_FEAT(RT_RUNTIME_SHARE, false)
+ SCHED_FEAT(LB_MIN, false)
+ SCHED_FEAT(ATTACH_AGE_LOAD, true)
+ 

diff --git a/queue-5.4/series b/queue-5.4/series
index 01449ce44789199b7f7ba072a73303f41e454840..53f942114e4f6b9125c4e197f74a5d34152131c3 100644 (file)
--- a/queue-5.4/series
+++ b/queue-5.4/series
@@ -14,3 +14,4 @@ cgroup-use-separate-src-dst-nodes-when-preloading-css_sets-for-migration.patch
 drm-panfrost-fix-shrinker-list-corruption-by-madvise-ioctl.patch
 nilfs2-fix-incorrect-masking-of-permission-flags-for-symlinks.patch
 revert-evm-fix-memleak-in-init_desc.patch
+sched-rt-disable-rt_runtime_share-by-default.patch