From 8d61eef756798cd33721e4c89bc72ce81792a3e8 Mon Sep 17 00:00:00 2001 From: Mark Rutland Date: Thu, 8 May 2025 14:26:30 +0100 Subject: [PATCH] arm64/fpsimd: Remove redundant task->mm check For historical reasons, arch_dup_task_struct() only calls fpsimd_preserve_current_state() when current->mm is non-NULL, but this is no longer necessary. Historically TIF_FOREIGN_FPSTATE was only managed for user threads, and was never set for kernel threads. At the time, various functions attempted to avoid saving/restoring state for kernel threads by checking task_struct::mm to try to distinguish user threads from kernel threads. We added the current->mm check to arch_dup_task_struct() in commit: 6eb6c80187c5 ("arm64: kernel thread don't need to save fpsimd context.") ... where the intent was to avoid pointlessly saving state for kernel threads, which never had live state (and the saved state would never be consumed). Subsequently we began setting TIF_FOREIGN_FPSTATE for kernel threads, and removed most of the task_struct::mm checks in commit: df3fb9682045 ("arm64: fpsimd: Eliminate task->mm checks") ... but we missed the check in arch_dup_task_struct(), which is similarly redundant. Remove the redundant check from arch_dup_task_struct(). Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Marc Zyngier Cc: Mark Brown Cc: Will Deacon Link: https://lore.kernel.org/r/20250508132644.1395904-11-mark.rutland@arm.com Signed-off-by: Will Deacon --- arch/arm64/kernel/process.c | 3 +-- 1 file changed, 1 insertion(+), 2 deletions(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 42faebb7b712..885c1adcf54c 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -344,8 +344,7 @@ void arch_release_task_struct(struct task_struct *tsk) int arch_dup_task_struct(struct task_struct *dst, struct task_struct *src) { - if (current->mm) - fpsimd_preserve_current_state(); + fpsimd_preserve_current_state(); *dst = *src; /* -- 2.50.1