From patchwork Thu Aug 10 04:13:46 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huacai Chen X-Patchwork-Id: 133690 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b824:0:b0:3f2:4152:657d with SMTP id z4csp191908vqi; Wed, 9 Aug 2023 22:09:47 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFCvQmL+3wuXD77G1NQsxWBJhoqIJHW+QjT4SqL5k48KbuIRbjCGQAyrwteh2ILTOrsWJbh X-Received: by 2002:a05:6512:3e26:b0:4f9:556b:93c4 with SMTP id i38-20020a0565123e2600b004f9556b93c4mr974711lfv.31.1691644187273; Wed, 09 Aug 2023 22:09:47 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1691644187; cv=none; d=google.com; s=arc-20160816; b=JTwUYsn3iGqKZuw1toP5QchqwwxgcMJTYLhw+Tv0g6pFnGzBDPzP7boNxuaRjJ3d27 PwE1gElrrTaIWPikxVSbcv5WYXRhq2Lixl3Hi2MLU1DH00srl6ma6S+y8VQejqnrSniR GilTZqdDw71UIUzjTdbEED/6iuRcul2MVv2RRvUDTa6mMcjKqGuVOEtbDTVk2oeoD9qN czQo7Ia/ZMRAk5q/2cIlEwTpKZ1AFYyKI5T0t/dKvJQVJWxsxriB4A7X0NJi4msz56A0 GhjBnH165kiU/IMNLewCy1lgGs7JobfX6yJeVkWlzjbd1xQHlfCMNp/K1z3L89eGkgjw Z8xQ== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :message-id:date:subject:cc:to:from; bh=bXBMd7zxOrYGzfBG86/JQ6Yos5Wtv4k8b8KqgGC/LDY=; fh=eU1Q4BmFOr1ZMPLcYiHt+coCOLdUynDiAGOBCBJLXUg=; b=RCcVmmAIpXzAK9nqkBciAZ9hQXQjqwewe1Tagjw3C4BQ7SIYiLVotCN9xix9xu1cOR Ticq6+bLy//gMux4javrd7zkGtn6oNnJbHUykZ6DKM/Z1HHXxk/lNA1iz3G1jYcyxye7 642dQKJ6Y8fC5qa6cQErUdvW6AsZNTgM3/y5xq53NHY/MQjyucZExyb+3u6vyfYU5+io LncvqZsIT95YTz3T3UteJiDwUQdZL6VfXM90tbVemh/MAP1WXlyAmYyeA8Ub9Za8j1dk ooVeb6dkstvS9SjHOD4Js/shNqr5xhm9q6ONuRAXJzZURZOGGAJRdUTlN0oiqfKIDHc5 OV1A== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id ay22-20020a056402203600b005222af11ff3si665452edb.509.2023.08.09.22.09.23; Wed, 09 Aug 2023 22:09:47 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232413AbjHJEOV (ORCPT + 99 others); Thu, 10 Aug 2023 00:14:21 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:54574 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229455AbjHJEOU (ORCPT ); Thu, 10 Aug 2023 00:14:20 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [139.178.84.217]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id ABDC1E7E; Wed, 9 Aug 2023 21:14:19 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 3DE1C64E7C; Thu, 10 Aug 2023 04:14:19 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id 65643C433C8; Thu, 10 Aug 2023 04:14:14 +0000 (UTC) From: Huacai Chen To: "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Thomas Gleixner , Ingo Molnar , John Stultz , Stephen Boyd Cc: Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Sergey Senozhatsky , chenhuacai@kernel.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Huacai Chen Subject: [PATCH 1/2] tick: Rename tick_do_update_jiffies64() and allow external usage Date: Thu, 10 Aug 2023 12:13:46 +0800 Message-Id: <20230810041347.3386770-1-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.39.3 MIME-Version: 1.0 X-Spam-Status: No, score=-6.7 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_HI,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773817495572694979 X-GMAIL-MSGID: 1773817495572694979 Rename tick_do_update_jiffies64() to do_update_jiffies_64() and move it to jiffies.c. This keeps the same naming style in jiffies.c and allow it be used by external components. This patch is a preparation for the next one which attempts to avoid necessary rcu stall warnings. Signed-off-by: Huacai Chen --- include/linux/jiffies.h | 2 + kernel/time/jiffies.c | 113 +++++++++++++++++++++++++++++++++++++- kernel/time/tick-sched.c | 113 +------------------------------------- kernel/time/timekeeping.h | 1 + 4 files changed, 117 insertions(+), 112 deletions(-) diff --git a/include/linux/jiffies.h b/include/linux/jiffies.h index 5e13f801c902..48866314c68b 100644 --- a/include/linux/jiffies.h +++ b/include/linux/jiffies.h @@ -88,6 +88,8 @@ static inline u64 get_jiffies_64(void) } #endif +void do_update_jiffies_64(s64 now); /* typedef s64 ktime_t */ + /* * These inlines deal with timer wrapping correctly. You are * strongly encouraged to use them diff --git a/kernel/time/jiffies.c b/kernel/time/jiffies.c index bc4db9e5ab70..507a1e7e619e 100644 --- a/kernel/time/jiffies.c +++ b/kernel/time/jiffies.c @@ -5,14 +5,14 @@ * Copyright (C) 2004, 2005 IBM, John Stultz (johnstul@us.ibm.com) */ #include +#include #include #include -#include +#include #include "timekeeping.h" #include "tick-internal.h" - static u64 jiffies_read(struct clocksource *cs) { return (u64) jiffies; @@ -61,6 +61,115 @@ EXPORT_SYMBOL(get_jiffies_64); EXPORT_SYMBOL(jiffies); +/* + * The time, when the last jiffy update happened. Write access must hold + * jiffies_lock and jiffies_seq. Because tick_nohz_next_event() needs to + * get a consistent view of jiffies and last_jiffies_update. + */ +ktime_t last_jiffies_update; + +/* + * Must be called with interrupts disabled ! + */ +void do_update_jiffies_64(ktime_t now) +{ +#if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS) + unsigned long ticks = 1; + ktime_t delta, nextp; + + /* + * 64bit can do a quick check without holding jiffies lock and + * without looking at the sequence count. The smp_load_acquire() + * pairs with the update done later in this function. + * + * 32bit cannot do that because the store of tick_next_period + * consists of two 32bit stores and the first store could move it + * to a random point in the future. + */ + if (IS_ENABLED(CONFIG_64BIT)) { + if (ktime_before(now, smp_load_acquire(&tick_next_period))) + return; + } else { + unsigned int seq; + + /* + * Avoid contention on jiffies_lock and protect the quick + * check with the sequence count. + */ + do { + seq = read_seqcount_begin(&jiffies_seq); + nextp = tick_next_period; + } while (read_seqcount_retry(&jiffies_seq, seq)); + + if (ktime_before(now, nextp)) + return; + } + + /* Quick check failed, i.e. update is required. */ + raw_spin_lock(&jiffies_lock); + /* + * Reevaluate with the lock held. Another CPU might have done the + * update already. + */ + if (ktime_before(now, tick_next_period)) { + raw_spin_unlock(&jiffies_lock); + return; + } + + write_seqcount_begin(&jiffies_seq); + + delta = ktime_sub(now, tick_next_period); + if (unlikely(delta >= TICK_NSEC)) { + /* Slow path for long idle sleep times */ + s64 incr = TICK_NSEC; + + ticks += ktime_divns(delta, incr); + + last_jiffies_update = ktime_add_ns(last_jiffies_update, + incr * ticks); + } else { + last_jiffies_update = ktime_add_ns(last_jiffies_update, + TICK_NSEC); + } + + /* Advance jiffies to complete the jiffies_seq protected job */ + jiffies_64 += ticks; + + /* + * Keep the tick_next_period variable up to date. + */ + nextp = ktime_add_ns(last_jiffies_update, TICK_NSEC); + + if (IS_ENABLED(CONFIG_64BIT)) { + /* + * Pairs with smp_load_acquire() in the lockless quick + * check above and ensures that the update to jiffies_64 is + * not reordered vs. the store to tick_next_period, neither + * by the compiler nor by the CPU. + */ + smp_store_release(&tick_next_period, nextp); + } else { + /* + * A plain store is good enough on 32bit as the quick check + * above is protected by the sequence count. + */ + tick_next_period = nextp; + } + + /* + * Release the sequence count. calc_global_load() below is not + * protected by it, but jiffies_lock needs to be held to prevent + * concurrent invocations. + */ + write_seqcount_end(&jiffies_seq); + + calc_global_load(); + + raw_spin_unlock(&jiffies_lock); + update_wall_time(); +#endif +} + static int __init init_jiffies_clocksource(void) { return __clocksource_register(&clocksource_jiffies); diff --git a/kernel/time/tick-sched.c b/kernel/time/tick-sched.c index 4df14db4da49..ea12d3cf89e7 100644 --- a/kernel/time/tick-sched.c +++ b/kernel/time/tick-sched.c @@ -44,113 +44,6 @@ struct tick_sched *tick_get_tick_sched(int cpu) } #if defined(CONFIG_NO_HZ_COMMON) || defined(CONFIG_HIGH_RES_TIMERS) -/* - * The time, when the last jiffy update happened. Write access must hold - * jiffies_lock and jiffies_seq. tick_nohz_next_event() needs to get a - * consistent view of jiffies and last_jiffies_update. - */ -static ktime_t last_jiffies_update; - -/* - * Must be called with interrupts disabled ! - */ -static void tick_do_update_jiffies64(ktime_t now) -{ - unsigned long ticks = 1; - ktime_t delta, nextp; - - /* - * 64bit can do a quick check without holding jiffies lock and - * without looking at the sequence count. The smp_load_acquire() - * pairs with the update done later in this function. - * - * 32bit cannot do that because the store of tick_next_period - * consists of two 32bit stores and the first store could move it - * to a random point in the future. - */ - if (IS_ENABLED(CONFIG_64BIT)) { - if (ktime_before(now, smp_load_acquire(&tick_next_period))) - return; - } else { - unsigned int seq; - - /* - * Avoid contention on jiffies_lock and protect the quick - * check with the sequence count. - */ - do { - seq = read_seqcount_begin(&jiffies_seq); - nextp = tick_next_period; - } while (read_seqcount_retry(&jiffies_seq, seq)); - - if (ktime_before(now, nextp)) - return; - } - - /* Quick check failed, i.e. update is required. */ - raw_spin_lock(&jiffies_lock); - /* - * Reevaluate with the lock held. Another CPU might have done the - * update already. - */ - if (ktime_before(now, tick_next_period)) { - raw_spin_unlock(&jiffies_lock); - return; - } - - write_seqcount_begin(&jiffies_seq); - - delta = ktime_sub(now, tick_next_period); - if (unlikely(delta >= TICK_NSEC)) { - /* Slow path for long idle sleep times */ - s64 incr = TICK_NSEC; - - ticks += ktime_divns(delta, incr); - - last_jiffies_update = ktime_add_ns(last_jiffies_update, - incr * ticks); - } else { - last_jiffies_update = ktime_add_ns(last_jiffies_update, - TICK_NSEC); - } - - /* Advance jiffies to complete the jiffies_seq protected job */ - jiffies_64 += ticks; - - /* - * Keep the tick_next_period variable up to date. - */ - nextp = ktime_add_ns(last_jiffies_update, TICK_NSEC); - - if (IS_ENABLED(CONFIG_64BIT)) { - /* - * Pairs with smp_load_acquire() in the lockless quick - * check above and ensures that the update to jiffies_64 is - * not reordered vs. the store to tick_next_period, neither - * by the compiler nor by the CPU. - */ - smp_store_release(&tick_next_period, nextp); - } else { - /* - * A plain store is good enough on 32bit as the quick check - * above is protected by the sequence count. - */ - tick_next_period = nextp; - } - - /* - * Release the sequence count. calc_global_load() below is not - * protected by it, but jiffies_lock needs to be held to prevent - * concurrent invocations. - */ - write_seqcount_end(&jiffies_seq); - - calc_global_load(); - - raw_spin_unlock(&jiffies_lock); - update_wall_time(); -} - /* * Initialize and return retrieve the jiffies update. */ @@ -207,7 +100,7 @@ static void tick_sched_do_timer(struct tick_sched *ts, ktime_t now) /* Check, if the jiffies need an update */ if (tick_do_timer_cpu == cpu) - tick_do_update_jiffies64(now); + do_update_jiffies_64(now); /* * If jiffies update stalled for too long (timekeeper in stop_machine() @@ -652,7 +545,7 @@ static void tick_nohz_update_jiffies(ktime_t now) __this_cpu_write(tick_cpu_sched.idle_waketime, now); local_irq_save(flags); - tick_do_update_jiffies64(now); + do_update_jiffies_64(now); local_irq_restore(flags); touch_softlockup_watchdog_sched(); @@ -975,7 +868,7 @@ static void tick_nohz_stop_sched_tick(struct tick_sched *ts, int cpu) static void tick_nohz_restart_sched_tick(struct tick_sched *ts, ktime_t now) { /* Update jiffies first */ - tick_do_update_jiffies64(now); + do_update_jiffies_64(now); /* * Clear the timer idle flag, so we avoid IPIs on remote queueing and diff --git a/kernel/time/timekeeping.h b/kernel/time/timekeeping.h index 543beba096c7..21670f6c7421 100644 --- a/kernel/time/timekeeping.h +++ b/kernel/time/timekeeping.h @@ -28,6 +28,7 @@ extern void update_wall_time(void); extern raw_spinlock_t jiffies_lock; extern seqcount_raw_spinlock_t jiffies_seq; +extern ktime_t last_jiffies_update; #define CS_NAME_LEN 32 From patchwork Thu Aug 10 04:13:47 2023 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Huacai Chen X-Patchwork-Id: 133688 Return-Path: Delivered-To: ouuuleilei@gmail.com Received: by 2002:a59:b824:0:b0:3f2:4152:657d with SMTP id z4csp190811vqi; Wed, 9 Aug 2023 22:06:42 -0700 (PDT) X-Google-Smtp-Source: AGHT+IFpuXSyWt1CDUodckxlV+/+iIvEeSposl8ZbPGiSx89gJ+TY9yJBc74eVw0K7eAD0P4TqTN X-Received: by 2002:aa7:d388:0:b0:523:22d9:6c39 with SMTP id x8-20020aa7d388000000b0052322d96c39mr1034013edq.38.1691644002020; Wed, 09 Aug 2023 22:06:42 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1691644002; cv=none; d=google.com; s=arc-20160816; b=ynGk+CxQry6LhjZ3cU1lpBEW5mLij0Xkr9PvyCCPvav3p86WvDljfOqYJbBeWvVe8s 6OLRgm5OYOjGEgd9/nWD/rJyNwTapxuq2dWOCR5QLInO7YSeR6PuCIAtPvISeBcq/ePm iJ3eFSWUZzOrLyelPXvS9MZac3nO7itpTVnqEALQrv8Cgcf6VMt2b7X3cSp3iriYobS9 fK+RpL8JFTdG51ruLVF+9/UaZNeyHx9KOpTZpUQRyZfLADyLSvjZ/KgCZeae6MKKvVHm vaQebwNboGWviGS+ev2y0Wr5HJ3ix+UjttApg+jJ+35aqp/MH8HrQoTqn7ZCP/9IYer5 jt4g== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:content-transfer-encoding:mime-version :references:in-reply-to:message-id:date:subject:cc:to:from; bh=xdNWi95q5X6l5HVRv+9IxQAPPefnx+iJNXpwKsDMq0s=; fh=ywtsktZ+ntA6irtAKTEomi+2QX8qaHTrVU5uOOcb8M4=; b=h0cNR/4Ak63wznAj/6yrguWfePX8a5j8YH5Gx49SwYBxwMW4LJKq0G27NyV8Y0E/5r qR+GmoZCdjfcoXBBn4gPCRm28eEmX8u5Qy3KJ0eqbzLoyi9xXN1EqPmlD8pMJHx1SMGE EMeohjR7bWmElz5S3aRMdVvZJZlrscioz4yh2TuScIi2EJ3MMEXEE/b3qEmJjaELbUCA itpnneLzRiwoH0WRTMeAWPBBElT5otMMSj5yiVOIMynHFsTZToaOdrRHmJAG3Viq8RP8 hgKnwzvhrldhsXN5VyPv1zjTNWHJ9A2ovwPUywms8h3+QmuU3f4Zqi2mopd9vAwYBIqW nYbA== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: from out1.vger.email (out1.vger.email. [2620:137:e000::1:20]) by mx.google.com with ESMTP id m5-20020aa7c485000000b00522d742bc4dsi638063edq.334.2023.08.09.22.06.18; Wed, 09 Aug 2023 22:06:42 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) client-ip=2620:137:e000::1:20; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 2620:137:e000::1:20 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232615AbjHJEOd (ORCPT + 99 others); Thu, 10 Aug 2023 00:14:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:41718 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229540AbjHJEOc (ORCPT ); Thu, 10 Aug 2023 00:14:32 -0400 Received: from dfw.source.kernel.org (dfw.source.kernel.org [IPv6:2604:1380:4641:c500::1]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id A58472112; Wed, 9 Aug 2023 21:14:30 -0700 (PDT) Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.3 with cipher TLS_AES_256_GCM_SHA384 (256/256 bits) key-exchange X25519 server-signature RSA-PSS (2048 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 203E164E82; Thu, 10 Aug 2023 04:14:30 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id E2EE4C433C9; Thu, 10 Aug 2023 04:14:24 +0000 (UTC) From: Huacai Chen To: "Paul E . McKenney" , Frederic Weisbecker , Neeraj Upadhyay , Joel Fernandes , Josh Triplett , Boqun Feng , Thomas Gleixner , Ingo Molnar , John Stultz , Stephen Boyd Cc: Steven Rostedt , Mathieu Desnoyers , Lai Jiangshan , Zqiang , Sergey Senozhatsky , chenhuacai@kernel.org, rcu@vger.kernel.org, linux-kernel@vger.kernel.org, Huacai Chen , stable@vger.kernel.org, Binbin Zhou Subject: [PATCH 2/2] rcu: Update jiffies in rcu_cpu_stall_reset() Date: Thu, 10 Aug 2023 12:13:47 +0800 Message-Id: <20230810041347.3386770-2-chenhuacai@loongson.cn> X-Mailer: git-send-email 2.39.3 In-Reply-To: <20230810041347.3386770-1-chenhuacai@loongson.cn> References: <20230810041347.3386770-1-chenhuacai@loongson.cn> MIME-Version: 1.0 X-Spam-Status: No, score=-4.0 required=5.0 tests=BAYES_00, HEADER_FROM_DIFFERENT_DOMAINS,RCVD_IN_DNSWL_MED,SPF_HELO_NONE,SPF_PASS autolearn=ham autolearn_force=no version=3.4.6 X-Spam-Checker-Version: SpamAssassin 3.4.6 (2021-04-09) on lindbergh.monkeyblade.net Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-GMAIL-THRID: 1773817301332418174 X-GMAIL-MSGID: 1773817301332418174 The KGDB initial breakpoint gets an rcu stall warning after commit a80be428fbc1f1f3bc9ed924 ("rcu: Do not disable GP stall detection in rcu_cpu_stall_reset()"). [ 53.452051] rcu: INFO: rcu_preempt self-detected stall on CPU [ 53.487950] rcu: 3-...0: (1 ticks this GP) idle=0e2c/1/0x4000000000000000 softirq=375/375 fqs=8 [ 53.528243] rcu: (t=12297 jiffies g=-995 q=1 ncpus=4) [ 53.564840] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc2+ #4848 [ 53.603005] Hardware name: Loongson Loongson-3A5000-HV-7A2000-1w-V0.1-CRB/Loongson-LS3A5000-7A2000-1w-CRB-V1.21, BIOS Loongson-UDK2018-V2.0.05099-beta8 08 [ 53.682062] pc 9000000000332100 ra 90000000003320f4 tp 90000001000a0000 sp 90000001000a3710 [ 53.724934] a0 9000000001d4b488 a1 0000000000000000 a2 0000000000000001 a3 0000000000000000 [ 53.768179] a4 9000000001d526c8 a5 90000001000a38f0 a6 000000000000002c a7 0000000000000000 [ 53.810751] t0 00000000000002b0 t1 0000000000000004 t2 900000000131c9c0 t3 fffffffffffffffa [ 53.853249] t4 0000000000000080 t5 90000001002ac190 t6 0000000000000004 t7 9000000001912d58 [ 53.895684] t8 0000000000000000 u0 90000000013141a0 s9 0000000000000028 s0 9000000001d512f0 [ 53.937633] s1 9000000001d51278 s2 90000001000a3798 s3 90000000019fc410 s4 9000000001d4b488 [ 53.979486] s5 9000000001d512f0 s6 90000000013141a0 s7 0000000000000078 s8 9000000001d4b450 [ 54.021175] ra: 90000000003320f4 kgdb_cpu_enter+0x534/0x640 [ 54.060150] ERA: 9000000000332100 kgdb_cpu_enter+0x540/0x640 [ 54.098347] CRMD: 000000b0 (PLV0 -IE -DA +PG DACF=CC DACM=CC -WE) [ 54.136621] PRMD: 0000000c (PPLV0 +PIE +PWE) [ 54.172192] EUEN: 00000000 (-FPE -SXE -ASXE -BTE) [ 54.207838] ECFG: 00071c1c (LIE=2-4,10-12 VS=7) [ 54.242503] ESTAT: 00000800 [INT] (IS=11 ECode=0 EsubCode=0) [ 54.277996] PRID: 0014c011 (Loongson-64bit, Loongson-3A5000-HV) [ 54.313544] CPU: 3 PID: 1 Comm: swapper/0 Not tainted 6.5.0-rc2+ #4848 [ 54.430170] Stack : 0072617764726148 0000000000000000 9000000000223504 90000001000a0000 [ 54.472308] 9000000100073a90 9000000100073a98 0000000000000000 9000000100073bd8 [ 54.514413] 9000000100073bd0 9000000100073bd0 9000000100073a00 0000000000000001 [ 54.556018] 0000000000000001 9000000100073a98 99828271f24e961a 90000001002810c0 [ 54.596924] 0000000000000001 0000000000010003 0000000000000000 0000000000000001 [ 54.637115] ffff8000337cdb80 0000000000000001 0000000006360000 900000000131c9c0 [ 54.677049] 0000000000000000 0000000000000000 90000000017b4c98 9000000001912000 [ 54.716394] 9000000001912f68 9000000001913000 9000000001912f70 00000000000002b0 [ 54.754880] 90000000014a8840 0000000000000000 900000000022351c 0000000000000000 [ 54.792372] 00000000000002b0 000000000000000c 0000000000000000 0000000000071c1c [ 54.829302] ... [ 54.859163] Call Trace: [ 54.859165] [<900000000022351c>] show_stack+0x5c/0x180 [ 54.918298] [<90000000012f6100>] dump_stack_lvl+0x60/0x88 [ 54.949251] [<90000000012dd5d8>] rcu_dump_cpu_stacks+0xf0/0x148 [ 54.981116] [<90000000002d2fb8>] rcu_sched_clock_irq+0xb78/0xe60 [ 55.012744] [<90000000002e47cc>] update_process_times+0x6c/0xc0 [ 55.044169] [<90000000002f65d4>] tick_sched_timer+0x54/0x100 [ 55.075488] [<90000000002e5174>] __hrtimer_run_queues+0x154/0x240 [ 55.107347] [<90000000002e6288>] hrtimer_interrupt+0x108/0x2a0 [ 55.139112] [<9000000000226418>] constant_timer_interrupt+0x38/0x60 [ 55.170749] [<90000000002b3010>] __handle_irq_event_percpu+0x50/0x160 [ 55.203141] [<90000000002b3138>] handle_irq_event_percpu+0x18/0x80 [ 55.235064] [<90000000002b9d54>] handle_percpu_irq+0x54/0xa0 [ 55.266241] [<90000000002b2168>] generic_handle_domain_irq+0x28/0x40 [ 55.298466] [<9000000000aba95c>] handle_cpu_irq+0x5c/0xa0 [ 55.329749] [<90000000012f7270>] handle_loongarch_irq+0x30/0x60 [ 55.361476] [<90000000012f733c>] do_vint+0x9c/0x100 [ 55.391737] [<9000000000332100>] kgdb_cpu_enter+0x540/0x640 [ 55.422440] [<9000000000332b64>] kgdb_handle_exception+0x104/0x180 [ 55.452911] [<9000000000232478>] kgdb_loongarch_notify+0x38/0xa0 [ 55.481964] [<900000000026b4d4>] notify_die+0x94/0x100 [ 55.509184] [<90000000012f685c>] do_bp+0x21c/0x340 [ 55.562475] [<90000000003315b8>] kgdb_compiled_break+0x0/0x28 [ 55.590319] [<9000000000332e80>] kgdb_register_io_module+0x160/0x1c0 [ 55.618901] [<9000000000c0f514>] configure_kgdboc+0x154/0x1c0 [ 55.647034] [<9000000000c0f5e0>] kgdboc_probe+0x60/0x80 [ 55.674647] [<9000000000c96da8>] platform_probe+0x68/0x100 [ 55.702613] [<9000000000c938e0>] really_probe+0xc0/0x340 [ 55.730528] [<9000000000c93be4>] __driver_probe_device+0x84/0x140 [ 55.759615] [<9000000000c93cdc>] driver_probe_device+0x3c/0x120 [ 55.787990] [<9000000000c93e8c>] __device_attach_driver+0xcc/0x160 [ 55.817145] [<9000000000c91290>] bus_for_each_drv+0x90/0x100 [ 55.845654] [<9000000000c94328>] __device_attach+0xa8/0x1a0 [ 55.874145] [<9000000000c925f0>] bus_probe_device+0xb0/0xe0 [ 55.902572] [<9000000000c8ec7c>] device_add+0x65c/0x860 [ 55.930635] [<9000000000c96704>] platform_device_add+0x124/0x2c0 [ 55.959669] [<9000000001452b38>] init_kgdboc+0x58/0xa0 [ 55.987677] [<900000000022015c>] do_one_initcall+0x7c/0x1e0 [ 56.016134] [<9000000001420f1c>] kernel_init_freeable+0x22c/0x2a0 [ 56.045128] [<90000000012f923c>] kernel_init+0x20/0x124 Currently rcu_cpu_stall_reset() set rcu_state.jiffies_stall to one check period later, i.e. jiffies + rcu_jiffies_till_stall_check(). But jiffies is only updated in the timer interrupt, so when kgdb_cpu_enter() begins to run there may already be nearly one rcu check period after jiffies. Since all interrupts are disabled during kgdb_cpu_enter(), jiffies will not be updated. When kgdb_cpu_enter() returns, rcu_state.jiffies_stall maybe already gets timeout. We can set rcu_state.jiffies_stall to two rcu check periods later, e.g. jiffies + (rcu_jiffies_till_stall_check() * 2) in rcu_cpu_stall_reset() to avoid this problem. But this isn't a complete solution because kgdb may take a very long time in irq disabled context. Instead, update jiffies at the beginning of rcu_cpu_stall_reset() can solve all kinds of problems. Cc: stable@vger.kernel.org Fixes: a80be428fbc1f1f3bc9ed924 ("rcu: Do not disable GP stall detection in rcu_cpu_stall_reset()") Reported-off-by: Binbin Zhou Signed-off-by: Huacai Chen --- kernel/rcu/tree_stall.h | 1 + 1 file changed, 1 insertion(+) diff --git a/kernel/rcu/tree_stall.h b/kernel/rcu/tree_stall.h index b10b8349bb2a..1c7b540985bf 100644 --- a/kernel/rcu/tree_stall.h +++ b/kernel/rcu/tree_stall.h @@ -153,6 +153,7 @@ static void panic_on_rcu_stall(void) */ void rcu_cpu_stall_reset(void) { + do_update_jiffies_64(ktime_get()); WRITE_ONCE(rcu_state.jiffies_stall, jiffies + rcu_jiffies_till_stall_check()); }