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=-6.9 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH, MAILING_LIST_MULTI,SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 373BFC35247 for ; Mon, 3 Feb 2020 16:42:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 0A4802086A for ; Mon, 3 Feb 2020 16:42:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=redhat.com header.i=@redhat.com header.b="fvM8y9CB" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1731668AbgBCQmX (ORCPT ); Mon, 3 Feb 2020 11:42:23 -0500 Received: from us-smtp-1.mimecast.com ([207.211.31.81]:33325 "EHLO us-smtp-delivery-1.mimecast.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1731622AbgBCQmL (ORCPT ); Mon, 3 Feb 2020 11:42:11 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=redhat.com; s=mimecast20190719; t=1580748130; h=from:from:reply-to:subject:subject:date:date:message-id:message-id: to:to:cc:cc:in-reply-to:in-reply-to:references:references; bh=wCvKQ4JLGeOrnlmXvELDlsXJNP6+GzB49Ia+dE2ltMk=; b=fvM8y9CBoC+t44gCjT0e3+AToppXZJ1dVqHvxTisWcYioesjCKG1kbCllt4Mer7HmeCAiO v/SQxgQqi6+QDpqAB/NE4+ts1P1J+hTY1UbMG0Nx5wP/xfBVv4rm86WKMJO/1TjpvhBcx2 tbyK90Hy616/gYk/Z+XJFATC1uzy2ZU= Received: from mimecast-mx01.redhat.com (mimecast-mx01.redhat.com [209.132.183.4]) (Using TLS) by relay.mimecast.com with ESMTP id us-mta-191-bbXsgzEUM5-ulUbOohRrzw-1; Mon, 03 Feb 2020 11:42:03 -0500 X-MC-Unique: bbXsgzEUM5-ulUbOohRrzw-1 Received: from smtp.corp.redhat.com (int-mx07.intmail.prod.int.phx2.redhat.com [10.5.11.22]) (using TLSv1.2 with cipher AECDH-AES256-SHA (256/256 bits)) (No client certificate requested) by mimecast-mx01.redhat.com (Postfix) with ESMTPS id 87C48107ACC7; Mon, 3 Feb 2020 16:42:02 +0000 (UTC) Received: from llong.com (dhcp-17-59.bos.redhat.com [10.18.17.59]) by smtp.corp.redhat.com (Postfix) with ESMTP id CE6AF1001B30; Mon, 3 Feb 2020 16:42:01 +0000 (UTC) From: Waiman Long To: Peter Zijlstra , Ingo Molnar , Will Deacon Cc: linux-kernel@vger.kernel.org, Bart Van Assche , Waiman Long Subject: [PATCH v5 4/7] locking/lockdep: Throw away all lock chains with zapped class Date: Mon, 3 Feb 2020 11:41:44 -0500 Message-Id: <20200203164147.17990-5-longman@redhat.com> In-Reply-To: <20200203164147.17990-1-longman@redhat.com> References: <20200203164147.17990-1-longman@redhat.com> X-Scanned-By: MIMEDefang 2.84 on 10.5.11.22 Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org If a lock chain contains a class that is zapped, the whole lock chain is likely to be invalid. If the zapped class is at the end of the chain, the partial chain without the zapped class should have been stored already as the current code will store all its predecessor chains. If the zapped class is somewhere in the middle, there is no guarantee that the partial chain will actually happen. It may just clutter up the hash and make searching slower. I would rather prefer storing the chain only when it actually happens. So just dump the corresponding chain_hlocks entries for now. A latter patch will try to reuse the freed chain_hlocks entries. This patch also changes the type of nr_chain_hlocks to unsigned integer to be consistent with the other counters. Signed-off-by: Waiman Long --- kernel/locking/lockdep.c | 37 ++++-------------------------- kernel/locking/lockdep_internals.h | 4 ++-- kernel/locking/lockdep_proc.c | 2 +- 3 files changed, 7 insertions(+), 36 deletions(-) diff --git a/kernel/locking/lockdep.c b/kernel/locking/lockdep.c index 28222d03345f..ef2a6432dd10 100644 --- a/kernel/locking/lockdep.c +++ b/kernel/locking/lockdep.c @@ -2625,8 +2625,8 @@ check_prevs_add(struct task_struct *curr, struct held_lock *next) struct lock_chain lock_chains[MAX_LOCKDEP_CHAINS]; static DECLARE_BITMAP(lock_chains_in_use, MAX_LOCKDEP_CHAINS); -int nr_chain_hlocks; static u16 chain_hlocks[MAX_LOCKDEP_CHAIN_HLOCKS]; +unsigned int nr_chain_hlocks; struct lock_class *lock_chain_get_class(struct lock_chain *chain, int i) { @@ -4772,36 +4772,23 @@ static void remove_class_from_lock_chain(struct pending_free *pf, struct lock_class *class) { #ifdef CONFIG_PROVE_LOCKING - struct lock_chain *new_chain; - u64 chain_key; int i; for (i = chain->base; i < chain->base + chain->depth; i++) { if (chain_hlocks[i] != class - lock_classes) continue; - /* The code below leaks one chain_hlock[] entry. */ - if (--chain->depth > 0) { - memmove(&chain_hlocks[i], &chain_hlocks[i + 1], - (chain->base + chain->depth - i) * - sizeof(chain_hlocks[0])); - } /* * Each lock class occurs at most once in a lock chain so once * we found a match we can break out of this loop. */ - goto recalc; + goto free_lock_chain; } /* Since the chain has not been modified, return. */ return; -recalc: - chain_key = INITIAL_CHAIN_KEY; - for (i = chain->base; i < chain->base + chain->depth; i++) - chain_key = iterate_chain_key(chain_key, chain_hlocks[i]); - if (chain->depth && chain->chain_key == chain_key) - return; +free_lock_chain: /* Overwrite the chain key for concurrent RCU readers. */ - WRITE_ONCE(chain->chain_key, chain_key); + WRITE_ONCE(chain->chain_key, INITIAL_CHAIN_KEY); dec_chains(chain->irq_context); /* @@ -4810,22 +4797,6 @@ static void remove_class_from_lock_chain(struct pending_free *pf, */ hlist_del_rcu(&chain->entry); __set_bit(chain - lock_chains, pf->lock_chains_being_freed); - if (chain->depth == 0) - return; - /* - * If the modified lock chain matches an existing lock chain, drop - * the modified lock chain. - */ - if (lookup_chain_cache(chain_key)) - return; - new_chain = alloc_lock_chain(); - if (WARN_ON_ONCE(!new_chain)) { - debug_locks_off(); - return; - } - *new_chain = *chain; - hlist_add_head_rcu(&new_chain->entry, chainhashentry(chain_key)); - inc_chains(new_chain->irq_context); #endif } diff --git a/kernel/locking/lockdep_internals.h b/kernel/locking/lockdep_internals.h index 76db80446a32..926bfa4b4564 100644 --- a/kernel/locking/lockdep_internals.h +++ b/kernel/locking/lockdep_internals.h @@ -134,14 +134,14 @@ extern unsigned long nr_zapped_classes; extern unsigned long nr_list_entries; long lockdep_next_lockchain(long i); unsigned long lock_chain_count(void); -extern int nr_chain_hlocks; extern unsigned long nr_stack_trace_entries; extern unsigned int nr_hardirq_chains; extern unsigned int nr_softirq_chains; extern unsigned int nr_process_chains; -extern unsigned int max_lockdep_depth; +extern unsigned int nr_chain_hlocks; +extern unsigned int max_lockdep_depth; extern unsigned int max_bfs_queue_depth; #ifdef CONFIG_PROVE_LOCKING diff --git a/kernel/locking/lockdep_proc.c b/kernel/locking/lockdep_proc.c index 453e497b6124..ca735cb83f48 100644 --- a/kernel/locking/lockdep_proc.c +++ b/kernel/locking/lockdep_proc.c @@ -278,7 +278,7 @@ static int lockdep_stats_show(struct seq_file *m, void *v) #ifdef CONFIG_PROVE_LOCKING seq_printf(m, " dependency chains: %11lu [max: %lu]\n", lock_chain_count(), MAX_LOCKDEP_CHAINS); - seq_printf(m, " dependency chain hlocks: %11d [max: %lu]\n", + seq_printf(m, " dependency chain hlocks: %11u [max: %lu]\n", nr_chain_hlocks, MAX_LOCKDEP_CHAIN_HLOCKS); #endif -- 2.18.1