From mboxrd@z Thu Jan 1 00:00:00 1970 Received: from r3-18.sinamail.sina.com.cn (r3-18.sinamail.sina.com.cn [202.108.3.18]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.subspace.kernel.org (Postfix) with ESMTPS id F3CFE3C3B for ; Thu, 16 Feb 2023 11:45:16 +0000 (UTC) Received: from unknown (HELO localhost.localdomain)([114.249.61.130]) by sina.com (172.16.97.35) with ESMTP id 63EE172500021753; Thu, 16 Feb 2023 19:44:39 +0800 (CST) X-Sender: hdanton@sina.com X-Auth-ID: hdanton@sina.com X-SMAIL-MID: 33284515074517 From: Hillf Danton To: Peng Zhang Cc: robin.murphy@arm.com, joro@8bytes.org, will@kernel.org, iommu@lists.linux.dev, linux-kernel@vger.kernel.org, Li Bin , Xie XiuQi , Yang Yingliang Subject: Re: [PATCH] iommu: Avoid softlockup and rcu stall in fq_flush_timeout(). Date: Thu, 16 Feb 2023 19:44:28 +0800 Message-Id: <20230216114428.1622-1-hdanton@sina.com> In-Reply-To: <65da1862-364b-9500-4be7-a463a12e6a7f@bytedance.com> References: <20230216084902.1486-1-hdanton@sina.com> Precedence: bulk X-Mailing-List: iommu@lists.linux.dev List-Id: List-Subscribe: List-Unsubscribe: MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit On Thu, 16 Feb 2023 19:02:59 +0800 Peng Zhang > 在 2023/2/16 16:49, Hillf Danton 写道: > > On Thu, 16 Feb 2023 15:11:48 +0800 Peng Zhang > >> There is softlockup under fio pressure test with smmu enabled: > >> watchdog: BUG: soft lockup - CPU#81 stuck for 22s! [swapper/81:0] > > > > What is your kernel version? > > Rcu stall occurs in kernel version 5.4. Info like 5.4 and the number of CPUs helps understand your work. > The test where the softlockup happened was not done by me, so I don't > know the kernel version. > However, it is the same as the code logic of fq_flush_timeout in the > mainline kernel. Could it be reproduced with mainline and a system with two CPUs?