Return-Path: X-Spam-Checker-Version: SpamAssassin 3.4.0 (2014-02-07) on aws-us-west-2-korg-lkml-1.web.codeaurora.org Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 75714C433FE for ; Mon, 22 Nov 2021 10:17:48 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S239203AbhKVKUx (ORCPT ); Mon, 22 Nov 2021 05:20:53 -0500 Received: from mail.loongson.cn ([114.242.206.163]:33114 "EHLO loongson.cn" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S236312AbhKVKUw (ORCPT ); Mon, 22 Nov 2021 05:20:52 -0500 Received: from linux.localdomain (unknown [113.200.148.30]) by mail.loongson.cn (Coremail) with SMTP id AQAAf9AxZ+hCbpthlxkAAA--.616S2; Mon, 22 Nov 2021 18:17:38 +0800 (CST) From: Tiezhu Yang To: Thomas Bogendoerfer Cc: Xuefeng Li , linux-mips@vger.kernel.org, linux-kernel@vger.kernel.org Subject: [PATCH] MIPS: Fix using smp_processor_id() in preemptible in show_cpuinfo() Date: Mon, 22 Nov 2021 18:17:37 +0800 Message-Id: <1637576257-11590-1-git-send-email-yangtiezhu@loongson.cn> X-Mailer: git-send-email 2.1.0 X-CM-TRANSID: AQAAf9AxZ+hCbpthlxkAAA--.616S2 X-Coremail-Antispam: 1UD129KBjvJXoW7WF47JF1Dur17Zr47ZryftFb_yoW8CFy3pa y7ArW8tr4UWw4DJa4rJrZagryrXFs8Za4IkayxJ3y3Za15WF1DXrnaqF4xuFyqgr4rta1I gF9FqF4Yga48ZaUanT9S1TB71UUUUUUqnTZGkaVYY2UrUUUUjbIjqfuFe4nvWSU5nxnvy2 9KBjDU0xBIdaVrnRJUUUvK14x267AKxVWUJVW8JwAFc2x0x2IEx4CE42xK8VAvwI8IcIk0 rVWrJVCq3wAFIxvE14AKwVWUJVWUGwA2ocxC64kIII0Yj41l84x0c7CEw4AK67xGY2AK02 1l84ACjcxK6xIIjxv20xvE14v26r4j6ryUM28EF7xvwVC0I7IYx2IY6xkF7I0E14v26r4j 6F4UM28EF7xvwVC2z280aVAFwI0_Cr1j6rxdM28EF7xvwVC2z280aVCY1x0267AKxVW0oV Cq3wAS0I0E0xvYzxvE52x082IY62kv0487Mc02F40EFcxC0VAKzVAqx4xG6I80ewAv7VAC jcxG62k0Y48FwI0_Jr0_Gr1lYx0E2Ix0cI8IcVAFwI0_Jr0_Jr4lYx0Ex4A2jsIE14v26r 1j6r4UMcvjeVCFs4IE7xkEbVWUJVW8JwACjcxG0xvY0x0EwIxGrwACjI8F5VA0II8E6IAq YI8I648v4I1lc2xSY4AK67AK6r4DMxAIw28IcxkI7VAKI48JMxC20s026xCaFVCjc4AY6r 1j6r4UMI8I3I0E5I8CrVAFwI0_Jr0_Jr4lx2IqxVCjr7xvwVAFwI0_JrI_JrWlx4CE17CE b7AF67AKxVWUAVWUtwCIc40Y0x0EwIxGrwCI42IY6xIIjxv20xvE14v26r1j6r1xMIIF0x vE2Ix0cI8IcVCY1x0267AKxVWUJVW8JwCI42IY6xAIw20EY4v20xvaj40_WFyUJVCq3wCI 42IY6I8E87Iv67AKxVWUJVW8JwCI42IY6I8E87Iv6xkF7I0E14v26r1j6r4UYxBIdaVFxh VjvjDU0xZFpf9x0JU38n5UUUUU= X-CM-SenderInfo: p1dqw3xlh2x3gn0dqz5rrqw2lrqou0/ Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org There exists the following issue under DEBUG_PREEMPT: BUG: using smp_processor_id() in preemptible [00000000] code: systemd/1 caller is show_cpuinfo+0x460/0xea0 ... Call Trace: [] show_stack+0x94/0x128 [] dump_stack_lvl+0x94/0xd8 [] check_preemption_disabled+0x104/0x110 [] show_cpuinfo+0x460/0xea0 [] seq_read_iter+0xfc/0x4f8 [] new_sync_read+0x110/0x1b8 [] vfs_read+0x1b4/0x1d0 [] ksys_read+0xd0/0x110 [] syscall_common+0x34/0x58 We can see the following call trace: show_cpuinfo() cpu_has_fpu current_cpu_data smp_processor_id() $ addr2line -f -e vmlinux 0xffffffff802209c8 show_cpuinfo arch/mips/kernel/proc.c:188 $ head -188 arch/mips/kernel/proc.c | tail -1 if (cpu_has_fpu) arch/mips/include/asm/cpu-features.h # define cpu_has_fpu (current_cpu_data.options & MIPS_CPU_FPU) arch/mips/include/asm/cpu-info.h #define current_cpu_data cpu_data[smp_processor_id()] Based on the above analysis, fix the issue by disabling preemption around cpu_has_fpu in show_cpuinfo(). Signed-off-by: Tiezhu Yang --- arch/mips/kernel/proc.c | 2 ++ 1 file changed, 2 insertions(+) diff --git a/arch/mips/kernel/proc.c b/arch/mips/kernel/proc.c index 376a6e2..c6c2661 100644 --- a/arch/mips/kernel/proc.c +++ b/arch/mips/kernel/proc.c @@ -185,8 +185,10 @@ static int show_cpuinfo(struct seq_file *m, void *v) seq_puts(m, " tx39_cache"); if (cpu_has_octeon_cache) seq_puts(m, " octeon_cache"); + preempt_disable(); if (cpu_has_fpu) seq_puts(m, " fpu"); + preempt_enable(); if (cpu_has_32fpr) seq_puts(m, " 32fpr"); if (cpu_has_cache_cdex_p) -- 2.1.0