From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org X-Spam-Level: X-Spam-Status: No, score=-9.8 required=3.0 tests=HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_PATCH,MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS, URIBL_BLOCKED,USER_AGENT_GIT autolearn=ham autolearn_force=no version=3.4.0 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id C3828C32753 for ; Wed, 14 Aug 2019 10:42:11 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A58B7216F4 for ; Wed, 14 Aug 2019 10:42:11 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727577AbfHNKl7 (ORCPT ); Wed, 14 Aug 2019 06:41:59 -0400 Received: from foss.arm.com ([217.140.110.172]:51934 "EHLO foss.arm.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727456AbfHNKlv (ORCPT ); Wed, 14 Aug 2019 06:41:51 -0400 Received: from usa-sjc-imap-foss1.foss.arm.com (unknown [10.121.207.14]) by usa-sjc-mx-foss1.foss.arm.com (Postfix) with ESMTP id 648A1360; Wed, 14 Aug 2019 03:41:51 -0700 (PDT) Received: from lakrids.cambridge.arm.com (usa-sjc-imap-foss1.foss.arm.com [10.121.207.14]) by usa-sjc-imap-foss1.foss.arm.com (Postfix) with ESMTPA id 8E2F63F706; Wed, 14 Aug 2019 03:41:49 -0700 (PDT) From: Mark Rutland To: linux-kernel@vger.kernel.org Cc: ak@linux.intel.com, akpm@linux-foundation.org, bigeasy@linutronix.de, bp@suse.de, catalin.marinas@arm.com, davem@davemloft.net, hch@lst.de, kan.liang@intel.com, mark.rutland@arm.com, mingo@kernel.org, peterz@infradead.org, riel@surriel.com, will@kernel.org Subject: [PATCH 5/9] arm64: correctly check for ktrheads Date: Wed, 14 Aug 2019 11:41:27 +0100 Message-Id: <20190814104131.20190-6-mark.rutland@arm.com> X-Mailer: git-send-email 2.11.0 In-Reply-To: <20190814104131.20190-1-mark.rutland@arm.com> References: <20190814104131.20190-1-mark.rutland@arm.com> Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Since commit: 6eb6c80187c55b7f ("arm64: kernel thread don't need to save fpsimd context.") ... we skip saving the fpsimd state for kernel threads in arch_dup_task_struct(). We determine whether current is a kthread by looking at current->mm. In general, a non-NULL current->mm doesn't imply that current is a kthread, as kthreads can install an mm via use_mm(), and so it's preferable to use is_kthread() to determine whether a thread is a kthread. For consistency, let's use is_kthread() here. Signed-off-by: Mark Rutland Cc: Catalin Marinas Cc: Ingo Molnar Cc: Peter Zijlstra Cc: Will Deacon --- arch/arm64/kernel/process.c | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-) diff --git a/arch/arm64/kernel/process.c b/arch/arm64/kernel/process.c index 288012687c29..82b0a7a257cd 100644 --- a/arch/arm64/kernel/process.c +++ b/arch/arm64/kernel/process.c @@ -335,7 +335,7 @@ 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) + if (!is_kthread(current)) fpsimd_preserve_current_state(); *dst = *src; -- 2.11.0