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 bombadil.infradead.org (bombadil.infradead.org [198.137.202.133]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by smtp.lore.kernel.org (Postfix) with ESMTPS id ACEABC433F5 for ; Fri, 7 Jan 2022 10:55:29 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=lists.infradead.org; s=bombadil.20210309; h=Sender: Content-Transfer-Encoding:Content-Type:List-Subscribe:List-Help:List-Post: List-Archive:List-Unsubscribe:List-Id:In-Reply-To:MIME-Version:References: Message-ID:Subject:Cc:To:From:Date:Reply-To:Content-ID:Content-Description: Resent-Date:Resent-From:Resent-Sender:Resent-To:Resent-Cc:Resent-Message-ID: List-Owner; bh=I08eZr5E5DNuBafMqAEVrr/a7jWFS3JUr5DsIiNx9Hk=; b=s++pY8wR1Q/7Nz wmDS9/FY0cWy2wM9DwIvCQPsyAy5P3EvdXa/BSFsHNPqQULgKHj9FGP4MD0SxsitpJBSQJB1p5X6e awA/baqhjTH/L7rggu1EzaYDeLMQa51bOd3LZ8ICTuf8KwbgjAm9iMsOk2Ioh9QzBZQCWSeoudqkX bh2tvtHSMBOs0ResxLRV3sn+OD0ZrQBWMt4vPxzOtBC8e8wYeMiUjEmy+wC4V2ejSdKaXNVzN6dIn ttXH4LCvTPKvXPHhcU6Z7vdD7JLIG2gg3zt6zMboNJeEMlYRaUCmZ4jHgXhrcsEfC2UK3/1i5p2oV q+ZPIk4o9M7sJCKWTQ5A==; Received: from localhost ([::1] helo=bombadil.infradead.org) by bombadil.infradead.org with esmtp (Exim 4.94.2 #2 (Red Hat Linux)) id 1n5msm-003V9m-32; Fri, 07 Jan 2022 10:54:04 +0000 Received: from dfw.source.kernel.org ([2604:1380:4641:c500::1]) by bombadil.infradead.org with esmtps (Exim 4.94.2 #2 (Red Hat Linux)) id 1n5msj-003V8j-1T for linux-arm-kernel@lists.infradead.org; Fri, 07 Jan 2022 10:54:02 +0000 Received: from smtp.kernel.org (relay.kernel.org [52.25.139.140]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by dfw.source.kernel.org (Postfix) with ESMTPS id 816F760A67; Fri, 7 Jan 2022 10:54:00 +0000 (UTC) Received: by smtp.kernel.org (Postfix) with ESMTPSA id C1FC0C36AE9; Fri, 7 Jan 2022 10:53:57 +0000 (UTC) Date: Fri, 7 Jan 2022 10:53:54 +0000 From: Catalin Marinas To: Jianyong Wu Cc: "will@kernel.org" , Anshuman Khandual , "akpm@linux-foundation.org" , "david@redhat.com" , "quic_qiancai@quicinc.com" , "ardb@kernel.org" , "linux-kernel@vger.kernel.org" , "linux-arm-kernel@lists.infradead.org" , "gshan@redhat.com" , Justin He , nd Subject: Re: [PATCH v3] arm64/mm: avoid fixmap race condition when create pud mapping Message-ID: References: <20211216082812.165387-1-jianyong.wu@arm.com> MIME-Version: 1.0 Content-Disposition: inline In-Reply-To: X-CRM114-Version: 20100106-BlameMichelson ( TRE 0.8.0 (BSD) ) MR-646709E3 X-CRM114-CacheID: sfid-20220107_025401_140847_328D76CB X-CRM114-Status: GOOD ( 12.57 ) X-BeenThere: linux-arm-kernel@lists.infradead.org X-Mailman-Version: 2.1.34 Precedence: list List-Id: List-Unsubscribe: , List-Archive: List-Post: List-Help: List-Subscribe: , Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit Sender: "linux-arm-kernel" Errors-To: linux-arm-kernel-bounces+linux-arm-kernel=archiver.kernel.org@lists.infradead.org On Fri, Jan 07, 2022 at 09:10:57AM +0000, Jianyong Wu wrote: > I roughly find the root cause. > alloc_init_pud will be called at the very beginning of kernel boot in > create_mapping_noalloc where no memory allocator is initialized. But > lockdep check may need allocate memory. So, kernel take exception > when acquire lock.(I have not found the exact code that cause this > issue) that's say we may not be able to use a lock so early. I couldn't find an slab or page allocation place either. It would be nice to get to the root cause rather than just avoiding the mutex on the early boot path. -- Catalin _______________________________________________ linux-arm-kernel mailing list linux-arm-kernel@lists.infradead.org http://lists.infradead.org/mailman/listinfo/linux-arm-kernel