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=-8.3 required=3.0 tests=DKIM_SIGNED,DKIM_VALID, DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS,USER_AGENT_SANE_1 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 E49F3C3A5A4 for ; Wed, 28 Aug 2019 21:43:24 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id B81A022CF8 for ; Wed, 28 Aug 2019 21:43:24 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="GvhKCTyM" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727078AbfH1VnX (ORCPT ); Wed, 28 Aug 2019 17:43:23 -0400 Received: from mail-pf1-f193.google.com ([209.85.210.193]:45863 "EHLO mail-pf1-f193.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726887AbfH1VnX (ORCPT ); Wed, 28 Aug 2019 17:43:23 -0400 Received: by mail-pf1-f193.google.com with SMTP id w26so594324pfq.12 for ; Wed, 28 Aug 2019 14:43:23 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=joelfernandes.org; s=google; h=date:from:to:cc:subject:message-id:references:mime-version :content-disposition:in-reply-to:user-agent; bh=RKU7RohOsxj+UeuRYGzxu1eVk2KwAL8JofUsXANZvgs=; b=GvhKCTyM7rCs+C3FlV0YHDhiydpck0aVyWoZoTh8XZFVftltXo/3m2XDAlmmbndBdj 0i6xc2C/aKhgb3V29HPhEyfu/qChj380lW+HHT2833a2xvlog+sCSImEOrz86Tfij5+G mcBfuETczxEjNZ+rVt+NVnvJzIY9hk+8OlUo4= X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:date:from:to:cc:subject:message-id:references :mime-version:content-disposition:in-reply-to:user-agent; bh=RKU7RohOsxj+UeuRYGzxu1eVk2KwAL8JofUsXANZvgs=; b=iS1T6kXyj5hlRpjkYW/ruEEz5XzQ0KpcIESwGGCr95Qh4NHBuFM5c8WkPYcYpZkpXR F9uvXmfCzKj8GxKjmXFZgqzkfNLtWmvlDfiswYXDHaTAygv2L27KTUumpVM+yDcMzvcR cFE9GglTpQRE4WAiiAOnMsyPgH3jYaEyp9h0NKYkC+7D+IC4XxCw/19TTMSA0153GgGU 44CuhuUsxHsy+Q/xpJLRjGRqFK/+RP/7n4dUeRy+0j6dp1j8JxAzjC4Kd89qUsmSEDaE MGwqw9AnLBVxuvq4XY2Zp4FF6j5Ronu9zE8QW90ljYKGoh9We2guIqq5veEOe8sfuFC9 iRHQ== X-Gm-Message-State: APjAAAXXxTphVRfzWXzjEQm6Gi0LM9yRhnn9+6IYJdT/oOkT80BKbDfO S5q37rSxZmmS0Gxzy8f+DBXqBg== X-Google-Smtp-Source: APXvYqyQJ8hU7BxGeoANDn5yV4OoWFaTZeQU7j7N2P6E7SfgqcDNJUvNKcDZG6XX0kYevyW+yypGvw== X-Received: by 2002:a63:df06:: with SMTP id u6mr5111636pgg.96.1567028602563; Wed, 28 Aug 2019 14:43:22 -0700 (PDT) Received: from localhost ([2620:15c:6:12:9c46:e0da:efbf:69cc]) by smtp.gmail.com with ESMTPSA id 4sm319542pfn.118.2019.08.28.14.43.21 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Wed, 28 Aug 2019 14:43:21 -0700 (PDT) Date: Wed, 28 Aug 2019 17:43:20 -0400 From: Joel Fernandes To: "Paul E. McKenney" Cc: linux-kernel@vger.kernel.org, byungchul.park@lge.com, Josh Triplett , Lai Jiangshan , linux-doc@vger.kernel.org, Mathieu Desnoyers , rcu@vger.kernel.org, Steven Rostedt , kernel-team@android.com Subject: Re: [PATCH 3/5] rcu/tree: Add support for debug_objects debugging for kfree_rcu() Message-ID: <20190828214320.GE75931@google.com> References: <5d657e37.1c69fb81.54250.01df@mx.google.com> <20190828213119.GY26530@linux.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190828213119.GY26530@linux.ibm.com> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Wed, Aug 28, 2019 at 02:31:19PM -0700, Paul E. McKenney wrote: > On Tue, Aug 27, 2019 at 03:01:57PM -0400, Joel Fernandes (Google) wrote: > > Make use of RCU's debug_objects debugging support > > (CONFIG_DEBUG_OBJECTS_RCU_HEAD) similar to call_rcu() and other flavors. > > Other flavors? Ah, call_srcu(), rcu_barrier(), and srcu_barrier(), > right? Yes. > > We queue the object during the kfree_rcu() call and dequeue it during > > reclaim. > > > > Tested that enabling CONFIG_DEBUG_OBJECTS_RCU_HEAD successfully detects > > double kfree_rcu() calls. > > > > Signed-off-by: Joel Fernandes (Google) > > The code looks good! thanks, does that mean you'll ack/apply it? :-P - Joel > > Thanx, Paul > > > --- > > kernel/rcu/tree.c | 8 ++++++++ > > 1 file changed, 8 insertions(+) > > > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > > index 9b9ae4db1c2d..64568f12641d 100644 > > --- a/kernel/rcu/tree.c > > +++ b/kernel/rcu/tree.c > > @@ -2757,6 +2757,7 @@ static void kfree_rcu_work(struct work_struct *work) > > for (; head; head = next) { > > next = head->next; > > /* Could be possible to optimize with kfree_bulk in future */ > > + debug_rcu_head_unqueue(head); > > __rcu_reclaim(rcu_state.name, head); > > cond_resched_tasks_rcu_qs(); > > } > > @@ -2868,6 +2869,13 @@ void kfree_call_rcu(struct rcu_head *head, rcu_callback_t func) > > if (rcu_scheduler_active != RCU_SCHEDULER_RUNNING) > > return kfree_call_rcu_nobatch(head, func); > > > > + if (debug_rcu_head_queue(head)) { > > + /* Probable double kfree_rcu() */ > > + WARN_ONCE(1, "kfree_call_rcu(): Double-freed call. rcu_head %p\n", > > + head); > > + return; > > + } > > + > > head->func = func; > > > > local_irq_save(flags); /* For safely calling this_cpu_ptr(). */ > > -- > > 2.23.0.187.g17f5b7556c-goog > >