From 0cfd6929fa780a3ec417858ab4fe2e8e46b16659 Mon Sep 17 00:00:00 2001
From: Linus Walleij <linus.walleij@linaro.org>
Date: Wed, 23 Oct 2024 13:05:34 +0100
Subject: [PATCH] ARM: 9431/1: mm: Pair atomic_set_release() with
_read_acquire()
commit 93ee385254d53849c01dd8ab9bc9d02790ee7f0e upstream.
The code for syncing vmalloc memory PGD pointers is using
atomic_read() in pair with atomic_set_release() but the
proper pairing is atomic_read_acquire() paired with
atomic_set_release().
This is done to clearly instruct the compiler to not
reorder the memcpy() or similar calls inside the section
so that we do not observe changes to init_mm. memcpy()
calls should be identified by the compiler as having
unpredictable side effects, but let's try to be on the
safe side.
Cc: stable@vger.kernel.org
Fixes: d31e23aff011 ("ARM: mm: make vmalloc_seq handling SMP safe")
Suggested-by: Mark Rutland <mark.rutland@arm.com>
Signed-off-by: Linus Walleij <linus.walleij@linaro.org>
Signed-off-by: Russell King (Oracle) <rmk+kernel@armlinux.org.uk>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
---
arch/arm/mm/ioremap.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)
diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c
index ff555823cceb8..89f1c97f3079c 100644
--- a/arch/arm/mm/ioremap.c
+++ b/arch/arm/mm/ioremap.c
@@ -141,7 +141,7 @@ void __check_vmalloc_seq(struct mm_struct *mm)
int seq;
do {
- seq = atomic_read(&init_mm.context.vmalloc_seq);
+ seq = atomic_read_acquire(&init_mm.context.vmalloc_seq);
memcpy_pgd(mm, VMALLOC_START, VMALLOC_END);
if (IS_ENABLED(CONFIG_KASAN_VMALLOC)) {
unsigned long start =
--
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