From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-pd0-f175.google.com (mail-pd0-f175.google.com [209.85.192.175]) by kanga.kvack.org (Postfix) with ESMTP id 0AD0E6B0036 for ; Wed, 21 May 2014 20:32:26 -0400 (EDT) Received: by mail-pd0-f175.google.com with SMTP id z10so1888536pdj.20 for ; Wed, 21 May 2014 17:32:26 -0700 (PDT) Received: from mail-pb0-x22a.google.com (mail-pb0-x22a.google.com [2607:f8b0:400e:c01::22a]) by mx.google.com with ESMTPS id al9si8297161pbd.15.2014.05.21.17.32.25 for (version=TLSv1 cipher=ECDHE-RSA-RC4-SHA bits=128/128); Wed, 21 May 2014 17:32:26 -0700 (PDT) Received: by mail-pb0-f42.google.com with SMTP id md12so1937806pbc.1 for ; Wed, 21 May 2014 17:32:25 -0700 (PDT) Message-ID: <1400718740.32269.7.camel@cyc> Subject: [PATCH v3] Distirbute the clear operation of mces_seen to Per-CPU rather than only monarch CPU From: Chen Yucong Date: Thu, 22 May 2014 08:32:20 +0800 Content-Type: text/plain; charset="UTF-8" Mime-Version: 1.0 Content-Transfer-Encoding: 7bit Sender: owner-linux-mm@kvack.org List-ID: To: hpa@zytor.com Cc: Naoya Horiguchi , Wu Fengguang , linux-mm , Andi Kleen mces_seen is a Per-CPU variable which should only be accessed by Per-CPU as possible. So the clear operation of mces_seen should also be local to Per-CPU rather than monarch CPU. Meanwhile, there is also a potential risk that mces_seen will not be be cleared if a timeout occurs in mce_end for monarch CPU. As a result, the stale value of mces_seen will reappear on the next mce. Based on the above reasons, this patch distribute the clear operation of mces_seen to Per-CPU rather than only monarch CPU. * From v1 * Add Reviewed-by: Andi Kleen * Put the clear operation of mces_seen before the MCG_STATUS write. * From v2 * Fix some misspelling in the patch message. Reviewed-by: Andi Kleen Signed-off-by: Chen Yucong --- arch/x86/kernel/cpu/mcheck/mce.c | 18 +++++++----------- 1 file changed, 7 insertions(+), 11 deletions(-) diff --git a/arch/x86/kernel/cpu/mcheck/mce.c b/arch/x86/kernel/cpu/mcheck/mce.c index 68317c8..966a5f5 100644 --- a/arch/x86/kernel/cpu/mcheck/mce.c +++ b/arch/x86/kernel/cpu/mcheck/mce.c @@ -785,13 +785,6 @@ static void mce_reign(void) */ if (global_worst <= MCE_KEEP_SEVERITY && mca_cfg.tolerant < 3) mce_panic("Machine check from unknown source", NULL, NULL); - - /* - * Now clear all the mces_seen so that they don't reappear on - * the next mce. - */ - for_each_possible_cpu(cpu) - memset(&per_cpu(mces_seen, cpu), 0, sizeof(struct mce)); } static atomic_t global_nwo; @@ -1137,9 +1130,6 @@ void do_machine_check(struct pt_regs *regs, long error_code) } } - /* mce_clear_state will clear *final, save locally for use later */ - m = *final; - if (!no_way_out) mce_clear_state(toclear); @@ -1161,7 +1151,7 @@ void do_machine_check(struct pt_regs *regs, long error_code) mce_panic("Fatal machine check on current CPU", &m, msg); if (worst == MCE_AR_SEVERITY) { /* schedule action before return to userland */ - mce_save_info(m.addr, m.mcgstatus & MCG_STATUS_RIPV); + mce_save_info(final->addr, final->mcgstatus & MCG_STATUS_RIPV); set_thread_flag(TIF_MCE_NOTIFY); } else if (kill_it) { force_sig(SIGBUS, current); @@ -1170,6 +1160,12 @@ void do_machine_check(struct pt_regs *regs, long error_code) if (worst > 0) mce_report_event(regs); + + /* + * Now clear the mces_seen of current CPU -*final - so that it does not + * reappear on the next mce. + */ + memset(final, 0, sizeof(struct mce)); mce_wrmsrl(MSR_IA32_MCG_STATUS, 0); out: atomic_dec(&mce_entry); -- 1.7.10.4 -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org