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=-16.8 required=3.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER,INCLUDES_PATCH, MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS,USER_AGENT_GIT autolearn=unavailable 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 8C609C07E99 for ; Mon, 5 Jul 2021 13:08:29 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 6CCF0613D1 for ; Mon, 5 Jul 2021 13:08:29 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231183AbhGENLF (ORCPT ); Mon, 5 Jul 2021 09:11:05 -0400 Received: from mail-m118208.qiye.163.com ([115.236.118.208]:25360 "EHLO mail-m118208.qiye.163.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S230188AbhGENLF (ORCPT ); Mon, 5 Jul 2021 09:11:05 -0400 X-Greylist: delayed 446 seconds by postgrey-1.27 at vger.kernel.org; Mon, 05 Jul 2021 09:11:04 EDT Received: from localhost.localdomain (unknown [113.118.122.203]) by mail-m118208.qiye.163.com (Hmail) with ESMTPA id C6A8CE03BD; Mon, 5 Jul 2021 21:00:58 +0800 (CST) From: Ding Hui To: tony.luck@intel.com, bp@alien8.de, bp@suse.de, naoya.horiguchi@nec.com, osalvador@suse.de, peterz@infradead.org Cc: linux-edac@vger.kernel.org, linux-kernel@vger.kernel.org, tglx@linutronix.de, mingo@redhat.com, x86@kernel.org, hpa@zytor.com, youquan.song@intel.com, huangcun@sangfor.com.cn, stable@vger.kernel.org, Ding Hui Subject: [PATCH v1] x86/mce: Fix endless loop when run task works after #MC Date: Mon, 5 Jul 2021 20:59:21 +0800 Message-Id: <20210705125921.936-1-dinghui@sangfor.com.cn> X-Mailer: git-send-email 2.17.1 X-HM-Spam-Status: e1kfGhgUHx5ZQUtXWQgYFAkeWUFZS1VLWVdZKFlBSE83V1ktWUFJV1kPCR oVCBIfWUFZQxhDT1ZJHUxOHR0eTkJMSk5VEwETFhoSFyQUDg9ZV1kWGg8SFR0UWUFZT0tIVUpKS0 hKQ1VLWQY+ X-HM-Sender-Digest: e1kMHhlZQR0aFwgeV1kSHx4VD1lBWUc6PVE6Sjo6Tz9WTRkWFEMTGU8T SRIwCzhVSlVKTUlOT0JLS05CTU5KVTMWGhIXVR8SFRwTDhI7CBoVHB0UCVUYFBZVGBVFWVdZEgtZ QVlKSkhVSkpDVUpJSVVJS0hZV1kIAVlBSE9CSTcG X-HM-Tid: 0a7a76c1f02a2c17kusnc6a8ce03bd Precedence: bulk List-ID: X-Mailing-List: linux-edac@vger.kernel.org Recently we encounter multi #MC on the same task when it's task_work_run() has not been called, current->mce_kill_me was added to task_works list more than once, that make a circular linked task_works, so task_work_run() will do a endless loop. More seriously, the SIGBUS signal can not be delivered to the userspace task which tigger the #MC and I met #MC flood. I borrowed mce_kill_me.func to check whether current->mce_kill_me has been added to task_works, prevent duplicate addition. When work function be called, the task_works must has been taken, so it is safe to be cleared in callback. Fixed: commit 5567d11c21a1 ("x86/mce: Send #MC singal from task work") Cc: #v5.8+ Signed-off-by: Ding Hui --- arch/x86/kernel/cpu/mce/core.c | 12 +++++++++--- 1 file changed, 9 insertions(+), 3 deletions(-) diff --git a/arch/x86/kernel/cpu/mce/core.c b/arch/x86/kernel/cpu/mce/core.c index 22791aadc085..32fb9ded6b85 100644 --- a/arch/x86/kernel/cpu/mce/core.c +++ b/arch/x86/kernel/cpu/mce/core.c @@ -1250,6 +1250,7 @@ static void __mc_scan_banks(struct mce *m, struct pt_regs *regs, struct mce *fin static void kill_me_now(struct callback_head *ch) { + WRITE_ONCE(ch->func, NULL); force_sig(SIGBUS); } @@ -1259,6 +1260,8 @@ static void kill_me_maybe(struct callback_head *cb) int flags = MF_ACTION_REQUIRED; int ret; + WRITE_ONCE(cb->func, NULL); + pr_err("Uncorrected hardware memory error in user-access at %llx", p->mce_addr); if (!p->mce_ripv) @@ -1289,17 +1292,20 @@ static void kill_me_maybe(struct callback_head *cb) static void queue_task_work(struct mce *m, int kill_current_task) { + struct callback_head ch; + current->mce_addr = m->addr; current->mce_kflags = m->kflags; current->mce_ripv = !!(m->mcgstatus & MCG_STATUS_RIPV); current->mce_whole_page = whole_page(m); if (kill_current_task) - current->mce_kill_me.func = kill_me_now; + ch.func = kill_me_now; else - current->mce_kill_me.func = kill_me_maybe; + ch.func = kill_me_maybe; - task_work_add(current, ¤t->mce_kill_me, TWA_RESUME); + if (!cmpxchg(¤t->mce_kill_me.func, NULL, ch.func)) + task_work_add(current, ¤t->mce_kill_me, TWA_RESUME); } /* -- 2.17.1