From 66ac1a4d366d3faa95fcf6082b555f8d77f1e8db Mon Sep 17 00:00:00 2001
From: Huacai Chen <chenhuacai@loongson.cn>
Date: Sun, 8 Jun 2025 22:12:35 +0800
Subject: init: fix build warnings about export.h

After commit a934a57a42f64a4 ("scripts/misc-check: check missing #include
<linux/export.h> when W=1") and 7d95680d64ac8e836c ("scripts/misc-check:
check unnecessary #include <linux/export.h> when W=1"), we get some build
warnings with W=1:

init/main.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing
init/initramfs.c: warning: EXPORT_SYMBOL() is used, but #include <linux/export.h> is missing

So fix these build warnings for the init code.

Link: https://lkml.kernel.org/r/20250608141235.155206-1-chenhuacai@loongson.cn
Fixes: a934a57a42f6 ("scripts/misc-check: check missing #include <linux/export.h> when W=1")
Signed-off-by: Huacai Chen <chenhuacai@loongson.cn>
Reviewed-by: Masahiro Yamada <masahiroy@kernel.org>
Cc: Al Viro <viro@zeniv.linux.org.uk>
Cc: Christian Brauner <brauner@kernel.org>
Cc: Jan Kara <jack@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---
 init/initramfs.c | 1 +
 init/main.c      | 1 +
 2 files changed, 2 insertions(+)

(limited to 'init')

diff --git a/init/initramfs.c b/init/initramfs.c
index 72bad44a1d41..097673b97784 100644
--- a/init/initramfs.c
+++ b/init/initramfs.c
@@ -1,6 +1,7 @@
 // SPDX-License-Identifier: GPL-2.0
 #include <linux/init.h>
 #include <linux/async.h>
+#include <linux/export.h>
 #include <linux/fs.h>
 #include <linux/slab.h>
 #include <linux/types.h>
diff --git a/init/main.c b/init/main.c
index ed576c7f475d..225a58279acd 100644
--- a/init/main.c
+++ b/init/main.c
@@ -13,6 +13,7 @@
 #define DEBUG		/* Enable initcall_debug */
 
 #include <linux/types.h>
+#include <linux/export.h>
 #include <linux/extable.h>
 #include <linux/module.h>
 #include <linux/proc_fs.h>
-- 
cgit v1.2.3


From 9a57c3773152a3ff2c35cc8325e088d011c9f83b Mon Sep 17 00:00:00 2001
From: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Date: Mon, 30 Jun 2025 16:50:34 +0200
Subject: futex: Temporary disable FUTEX_PRIVATE_HASH

Chris Mason reported a performance regression on big iron. Reports of
this kind were usually reported as part of a micro benchmark but Chris'
test did mimic his real workload. This makes it a real regression.

The root cause is rcuref_get() which is invoked during each futex
operation. If all threads of an application do this simultaneously then
it leads to cache line bouncing and the performance drops.

Disable FUTEX_PRIVATE_HASH entirely for this cycle. The performance
regression will be addressed in the following cycle enabling the option
again.

Closes: https://lore.kernel.org/all/3ad05298-351e-4d61-9972-ca45a0a50e33@meta.com/
Reported-by: Chris Mason <clm@meta.com>
Signed-off-by: Sebastian Andrzej Siewior <bigeasy@linutronix.de>
Signed-off-by: Peter Zijlstra (Intel) <peterz@infradead.org>
Link: https://lkml.kernel.org/r/20250630145034.8JnINEaS@linutronix.de
---
 init/Kconfig | 4 ++++
 1 file changed, 4 insertions(+)

(limited to 'init')

diff --git a/init/Kconfig b/init/Kconfig
index af4c2f085455..666783eb50ab 100644
--- a/init/Kconfig
+++ b/init/Kconfig
@@ -1716,9 +1716,13 @@ config FUTEX_PI
 	depends on FUTEX && RT_MUTEXES
 	default y
 
+#
+# marked broken for performance reasons; gives us one more cycle to sort things out.
+#
 config FUTEX_PRIVATE_HASH
 	bool
 	depends on FUTEX && !BASE_SMALL && MMU
+	depends on BROKEN
 	default y
 
 config FUTEX_MPOL
-- 
cgit v1.2.3