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 Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by smtp.lore.kernel.org (Postfix) with ESMTP id 3AFE6C433EF for ; Thu, 19 May 2022 21:05:11 +0000 (UTC) Received: by kanga.kvack.org (Postfix) id A5A116B0071; Thu, 19 May 2022 17:05:10 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id A0AD46B0072; Thu, 19 May 2022 17:05:10 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 8AA736B0073; Thu, 19 May 2022 17:05:10 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from relay.hostedemail.com (smtprelay0015.hostedemail.com [216.40.44.15]) by kanga.kvack.org (Postfix) with ESMTP id 7966E6B0071 for ; Thu, 19 May 2022 17:05:10 -0400 (EDT) Received: from smtpin31.hostedemail.com (a10.router.float.18 [10.200.18.1]) by unirelay01.hostedemail.com (Postfix) with ESMTP id 4B12A6124A for ; Thu, 19 May 2022 21:05:10 +0000 (UTC) X-FDA: 79483722780.31.EAE48D0 Received: from alexa-out-sd-02.qualcomm.com (alexa-out-sd-02.qualcomm.com [199.106.114.39]) by imf17.hostedemail.com (Postfix) with ESMTP id 2D33D400E5 for ; Thu, 19 May 2022 21:04:43 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=quicinc.com; i=@quicinc.com; q=dns/txt; s=qcdkim; t=1652994309; x=1684530309; h=date:from:to:cc:subject:message-id:references: mime-version:in-reply-to; bh=Q/iVT6eHGUL7xt25EZCD9Iruv1QN8td0bn1+mXm/2MM=; b=Qx/efrWaMSVrFFveZQTKz/zcukXXzwgMg1u5WEzbYm+DV0sizz141scC p5dRPe4DWq7KhQlqIghuxHxu9yGcYjm2RJ344VIZlNjEwlKOiXBG8HWwm Gc6GJKMliPtnYriYGhOeeitCNa/xTVr0buadiIY5o8/iFb/wtNn8Ke/kY Q=; Received: from unknown (HELO ironmsg04-sd.qualcomm.com) ([10.53.140.144]) by alexa-out-sd-02.qualcomm.com with ESMTP; 19 May 2022 14:05:08 -0700 X-QCInternal: smtphost Received: from nasanex01c.na.qualcomm.com ([10.47.97.222]) by ironmsg04-sd.qualcomm.com with ESMTP/TLS/ECDHE-RSA-AES256-GCM-SHA384; 19 May 2022 14:05:08 -0700 Received: from nalasex01a.na.qualcomm.com (10.47.209.196) by nasanex01c.na.qualcomm.com (10.47.97.222) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Thu, 19 May 2022 14:05:07 -0700 Received: from qian (10.80.80.8) by nalasex01a.na.qualcomm.com (10.47.209.196) with Microsoft SMTP Server (version=TLS1_2, cipher=TLS_ECDHE_RSA_WITH_AES_256_GCM_SHA384) id 15.2.986.22; Thu, 19 May 2022 14:05:06 -0700 Date: Thu, 19 May 2022 17:05:04 -0400 From: Qian Cai To: "Paul E. McKenney" CC: Mel Gorman , Andrew Morton , Nicolas Saenz Julienne , Marcelo Tosatti , Vlastimil Babka , Michal Hocko , LKML , Linux-MM , , Subject: Re: [PATCH 0/6] Drain remote per-cpu directly v3 Message-ID: References: <20220512085043.5234-1-mgorman@techsingularity.net> <20220517233507.GA423@qian> <20220518125152.GQ3441@techsingularity.net> <20220518171503.GQ1790663@paulmck-ThinkPad-P17-Gen-1> <20220519191524.GC1790663@paulmck-ThinkPad-P17-Gen-1> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Disposition: inline In-Reply-To: <20220519191524.GC1790663@paulmck-ThinkPad-P17-Gen-1> X-Originating-IP: [10.80.80.8] X-ClientProxiedBy: nasanex01b.na.qualcomm.com (10.46.141.250) To nalasex01a.na.qualcomm.com (10.47.209.196) X-Stat-Signature: y469qhws7anz39atzk7uj7jam3shfecm X-Rspamd-Server: rspam07 X-Rspamd-Queue-Id: 2D33D400E5 X-Rspam-User: Authentication-Results: imf17.hostedemail.com; dkim=pass header.d=quicinc.com header.s=qcdkim header.b="Qx/efrWa"; dmarc=pass (policy=none) header.from=quicinc.com; spf=pass (imf17.hostedemail.com: domain of quic_qiancai@quicinc.com designates 199.106.114.39 as permitted sender) smtp.mailfrom=quic_qiancai@quicinc.com X-HE-Tag: 1652994283-497264 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Thu, May 19, 2022 at 12:15:24PM -0700, Paul E. McKenney wrote: > Is the task doing offline_pages()->synchronize_rcu() doing this > repeatedly? Or is there a stalled RCU grace period? (From what > I can see, offline_pages() is not doing huge numbers of calls to > synchronize_rcu() in any of its loops, but I freely admit that I do not > know this code.) Yes, we are running into an endless loop in isolate_single_pageblock(). There was a similar issue happened not long ago, so I am wondering if we did not solve it entirely then. Anyway, I will continue the thread over there. https://lore.kernel.org/all/YoavU%2F+NfQIzQiDF@qian/ > Or is it possible that reverting those three patches simply decreases > the probability of failure, rather than eliminating the failure? > Such a decrease could be due to many things, for example, changes to > offsets and sizes of data structures. Entirely possible. Sorry for the false alarm. > Do you ever see RCU CPU stall warnings? No.