From: Linus Walleij Date: Wed, 23 Oct 2024 12:05:34 +0000 (+0100) Subject: ARM: 9431/1: mm: Pair atomic_set_release() with _read_acquire() X-Git-Tag: microblaze-v6.16~500^2 X-Git-Url: http://git.monstr.eu/?a=commitdiff_plain;h=93ee385254d53849c01dd8ab9bc9d02790ee7f0e;p=linux-2.6-microblaze.git ARM: 9431/1: mm: Pair atomic_set_release() with _read_acquire() 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 Signed-off-by: Linus Walleij Signed-off-by: Russell King (Oracle) --- diff --git a/arch/arm/mm/ioremap.c b/arch/arm/mm/ioremap.c index ff555823cceb..89f1c97f3079 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 =