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=-8.4 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=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 CF72AC3A589 for ; Fri, 16 Aug 2019 02:58:15 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9F9322086C for ; Fri, 16 Aug 2019 02:58:15 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=joelfernandes.org header.i=@joelfernandes.org header.b="YodcmsOm" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726506AbfHPC6P (ORCPT ); Thu, 15 Aug 2019 22:58:15 -0400 Received: from mail-pg1-f195.google.com ([209.85.215.195]:46227 "EHLO mail-pg1-f195.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726279AbfHPC6P (ORCPT ); Thu, 15 Aug 2019 22:58:15 -0400 Received: by mail-pg1-f195.google.com with SMTP id m3so1601557pgv.13 for ; Thu, 15 Aug 2019 19:58:14 -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=YtVSxAhqmLmaZlh2TsP7vbj4SsCXa4o14qm4MdzQM3A=; b=YodcmsOmhsDjkCJOgPqbCLZnaJgBGEo+MVJs2tC8NwBzd56aDyXcNWFH+i+H7zCzhv A7LXPj1WbPPuJczkMLkUOBAgyc6SPn8IO3mWnir1sdXkeAlxg1lz7cdNJZBOGquPBSp7 9YbjQptJUsoeUs33mfAPYNob6arq0fZcyxGtg= 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=YtVSxAhqmLmaZlh2TsP7vbj4SsCXa4o14qm4MdzQM3A=; b=Zi1Oxkt4Hc1HNZzYQwbHZ5EYzvhRVF7fEqivapvNbMAxhF1VJ4OQKfo8WW6gR1no5p vlII4PHLwdV7oXnmkyCvBW45dp3g8P4GCBFlWxOP0LoHPruo8Akuojw/FTVBjvoLPOF2 l0j8cxNaFcqUDal+rYJPgoHPhe9ATIJji9TEem75w3KAc+rXhX9TG5a6WsgA0nsFY8Qt ezFTXy2FK8hFa7qjyeUjyUIPTUuSiJyEG9VeostfdbUNvJS8rpHHmCjUGsqf513SQk4H lnwQ97Ss3FKvIXL0fhopBjXCe0vgDRIF0SbO9wcaIn639iZGmek4pz6G1BaiVkbqRsUT 3sjA== X-Gm-Message-State: APjAAAVopAvRt1naiU3oXDNFUZxJIGCiE9kRgoaPqnUefIgv2AU9Pidv w/1uAQ76wySykn8WRcwrv/hhcg== X-Google-Smtp-Source: APXvYqw4/rZERyh5roKWAxzUuwlbuQc0ChvNdlv9/ntweB0nYScM+MYren8mxvM48laxtRbG0RoQxQ== X-Received: by 2002:a62:1808:: with SMTP id 8mr8607111pfy.177.1565924294327; Thu, 15 Aug 2019 19:58:14 -0700 (PDT) Received: from localhost ([172.19.216.18]) by smtp.gmail.com with ESMTPSA id y16sm4283794pfn.173.2019.08.15.19.58.13 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Thu, 15 Aug 2019 19:58:13 -0700 (PDT) Date: Thu, 15 Aug 2019 22:57:56 -0400 From: Joel Fernandes To: linux-kernel@vger.kernel.org Cc: rcu@vger.kernel.org, "Paul E. McKenney" , frederic@kernel.org Subject: Re: [PATCH -rcu dev 2/3] rcu/tree: Fix issue where sometimes rcu_urgent_qs is not set on IPI Message-ID: <20190816025756.GA242309@google.com> References: <20190816025311.241257-1-joel@joelfernandes.org> <20190816025311.241257-2-joel@joelfernandes.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20190816025311.241257-2-joel@joelfernandes.org> User-Agent: Mutt/1.10.1 (2018-07-13) Sender: rcu-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: rcu@vger.kernel.org On Thu, Aug 15, 2019 at 10:53:10PM -0400, Joel Fernandes (Google) wrote: > Sometimes I see rcu_urgent_qs is not set. This could be when the last > IPI was a long time ago, however, the grace period just started. Set > rcu_urgent_qs so the tick can indeed be stopped. Here I meant: not be stopped. I will resend the patch as v2. thanks, - Joel > > Signed-off-by: Joel Fernandes (Google) > --- > kernel/rcu/tree.c | 1 + > 1 file changed, 1 insertion(+) > > diff --git a/kernel/rcu/tree.c b/kernel/rcu/tree.c > index 322b1b57967c..856d3c9f1955 100644 > --- a/kernel/rcu/tree.c > +++ b/kernel/rcu/tree.c > @@ -1091,6 +1091,7 @@ static int rcu_implicit_dynticks_qs(struct rcu_data *rdp) > if (tick_nohz_full_cpu(rdp->cpu) && > time_after(jiffies, > READ_ONCE(rdp->last_fqs_resched) + jtsq * 3)) { > + WRITE_ONCE(*ruqp, true); > resched_cpu(rdp->cpu); > WRITE_ONCE(rdp->last_fqs_resched, jiffies); > } > -- > 2.23.0.rc1.153.gdeed80330f-goog >