Received: by 2002:a25:1985:0:0:0:0:0 with SMTP id 127csp2560952ybz; Sun, 26 Apr 2020 23:12:26 -0700 (PDT) X-Google-Smtp-Source: APiQypL7ywYOvC1mNiyJ3SGlvL75vpFGZjz1rYY2YX2ovum2uPGLIvrx+bvuTbBvn/zC5fC0Trkc X-Received: by 2002:a17:907:1119:: with SMTP id qu25mr12435836ejb.291.1587967946017; Sun, 26 Apr 2020 23:12:26 -0700 (PDT) ARC-Seal: i=1; a=rsa-sha256; t=1587967946; cv=none; d=google.com; s=arc-20160816; b=q+7EPcQWFQ+8jIz/2hZYTFvmiMhEBsMylm57R3WsKNpTrcTqg4a+J9Vfmo/pAjNh/J hyWdlUE8ty916XSWDzrLOXoi8qtmv6qvlzgdkQHkeB+LHcnF9G2b/UnnqObsrGoPMg3y ZKX4W4L8zM+4My9ZGQv8ypqXr/84nzzjYL5a/XCNaYLNBMUXBfdQ13Yun/hBLIj0Qnp4 9qHaFxomKdChsILrOJKoA38oKvLyfDKsvNgNiomxLmJcde9E9YozUZGGgzrfD4DM/vBL 0/bbypebliVQU0Tn3hB8OQbCHhDt912dWLndEwAeighwWEea7OfqX/CZYuqVF8/j2r4y UHXw== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=arc-20160816; h=list-id:precedence:sender:content-transfer-encoding :content-language:in-reply-to:mime-version:user-agent:date :message-id:from:references:cc:to:subject; bh=jarFmF2Oa82cNVc/HKobchz3BinECNtiAFkkvpNJtf8=; b=q4QW2jGfAImNYPFTRrkm1dPA+VgvC37RTG0mBmB3p5KyVmv1bSo5t6bpV7+sa3IhRC E4W0n1mo+A5ApGjcN4TqH5XdJGLv0U2D93+zzUor61Y5qYZ5rpm4SfYXinI6as1Ew0f6 tP0lkXGBpC3Q38KS8IGbbDLbatjPO6AbhXIHmJk3SAvxworurrOt/s1eU3vHp519EyQi GhtezwmNQv7Z6yk20qhOXDJ5jlRHfZyFRfP4NVc2T3kcEBkpesvoHQU8Lxem+gauEhSM ZluEnXqJ94cZNJknrho36hfpJlW4s6fyXS+h3lukpnbYz2MxrX413zHN1aJp3S5pnbRa uAkg== ARC-Authentication-Results: i=1; mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Return-Path: Received: from vger.kernel.org (vger.kernel.org. [23.128.96.18]) by mx.google.com with ESMTP id y23si7128657edt.99.2020.04.26.23.12.03; Sun, 26 Apr 2020 23:12:26 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726339AbgD0GIr (ORCPT + 99 others); Mon, 27 Apr 2020 02:08:47 -0400 Received: from szxga06-in.huawei.com ([45.249.212.32]:51230 "EHLO huawei.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1726221AbgD0GIr (ORCPT ); Mon, 27 Apr 2020 02:08:47 -0400 Received: from DGGEMS402-HUB.china.huawei.com (unknown [172.30.72.58]) by Forcepoint Email with ESMTP id 3D62DCE1779533C62C14; Mon, 27 Apr 2020 14:08:45 +0800 (CST) Received: from [10.134.22.195] (10.134.22.195) by smtp.huawei.com (10.3.19.202) with Microsoft SMTP Server (TLS) id 14.3.487.0; Mon, 27 Apr 2020 14:08:40 +0800 Subject: Re: [PATCH V2] f2fs: Avoid double lock for cp_rwsem during checkpoint To: Sayali Lokhande , , CC: , References: <1587967204-24824-1-git-send-email-sayalil@codeaurora.org> From: Chao Yu Message-ID: <6cfb8f00-a36c-03b9-ffa7-12fe37a19317@huawei.com> Date: Mon, 27 Apr 2020 14:08:39 +0800 User-Agent: Mozilla/5.0 (Windows NT 6.1; WOW64; rv:52.0) Gecko/20100101 Thunderbird/52.9.1 MIME-Version: 1.0 In-Reply-To: <1587967204-24824-1-git-send-email-sayalil@codeaurora.org> Content-Type: text/plain; charset="windows-1252" Content-Language: en-US Content-Transfer-Encoding: 7bit X-Originating-IP: [10.134.22.195] X-CFilter-Loop: Reflected Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 2020/4/27 14:00, Sayali Lokhande wrote: > There could be a scenario where f2fs_sync_node_pages gets > called during checkpoint, which in turn tries to flush > inline data and calls iput(). This results in deadlock as > iput() tries to hold cp_rwsem, which is already held at the > beginning by checkpoint->block_operations(). > > Call stack : > > Thread A Thread B > f2fs_write_checkpoint() > - block_operations(sbi) > - f2fs_lock_all(sbi); > - down_write(&sbi->cp_rwsem); > > - open() > - igrab() > - write() write inline data > - unlink() > - f2fs_sync_node_pages() > - if (is_inline_node(page)) > - flush_inline_data() > - ilookup() > page = f2fs_pagecache_get_page() > if (!page) > goto iput_out; > iput_out: > > - iput() ^^^^ - close() - iput() > iput(inode); > - f2fs_evict_inode() > - f2fs_truncate_blocks() > - f2fs_lock_op() > - down_read(&sbi->cp_rwsem); > > Signed-off-by: Sayali Lokhande Reviewed-by: Chao Yu Thanks,