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=-1.0 required=3.0 tests=MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED autolearn=no 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 552CCC432C0 for ; Mon, 18 Nov 2019 20:41:42 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 20A0C20708 for ; Mon, 18 Nov 2019 20:41:42 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1726717AbfKRUll convert rfc822-to-8bit (ORCPT ); Mon, 18 Nov 2019 15:41:41 -0500 Received: from mail.kernel.org ([198.145.29.99]:50630 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1726536AbfKRUll (ORCPT ); Mon, 18 Nov 2019 15:41:41 -0500 From: bugzilla-daemon@bugzilla.kernel.org To: linux-ext4@vger.kernel.org Subject: [Bug 205569] New: potential data race (likely benign) on inode->i_state (reading and writing to different bits) Date: Mon, 18 Nov 2019 20:41:40 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: new X-Bugzilla-Watch-Reason: AssignedTo fs_ext4@kernel-bugs.osdl.org X-Bugzilla-Product: File System X-Bugzilla-Component: ext4 X-Bugzilla-Version: 2.5 X-Bugzilla-Keywords: X-Bugzilla-Severity: normal X-Bugzilla-Who: mengxu.gatech@gmail.com X-Bugzilla-Status: NEW X-Bugzilla-Resolution: X-Bugzilla-Priority: P1 X-Bugzilla-Assigned-To: fs_ext4@kernel-bugs.osdl.org X-Bugzilla-Flags: X-Bugzilla-Changed-Fields: bug_id short_desc product version cf_kernel_version rep_platform op_sys cf_tree bug_status bug_severity priority component assigned_to reporter cf_regression Message-ID: Content-Type: text/plain; charset="UTF-8" Content-Transfer-Encoding: 8BIT X-Bugzilla-URL: https://bugzilla.kernel.org/ Auto-Submitted: auto-generated MIME-Version: 1.0 Sender: linux-ext4-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-ext4@vger.kernel.org https://bugzilla.kernel.org/show_bug.cgi?id=205569 Bug ID: 205569 Summary: potential data race (likely benign) on inode->i_state (reading and writing to different bits) Product: File System Version: 2.5 Kernel Version: 5.4-rc5 Hardware: All OS: Linux Tree: Mainline Status: NEW Severity: normal Priority: P1 Component: ext4 Assignee: fs_ext4@kernel-bugs.osdl.org Reporter: mengxu.gatech@gmail.com Regression: No I am reporting a potential data race (maybe benign) in the ext4 layer on inode->i_state, with reading and writing to the same byte but different bits: I_DIRTY_PAGES (bit 2) and I_NEW | I_FREEING (bit 3 and 5), observable during the write-back phase. The function call trace is shown below: [Thread 1: SYS_rmdir] __do_sys_rmdir do_rmdir vfs_rmdir ext4_rmdir ext4_orphan_add [READ] WARN_ON_ONCE(!(inode->i_state & (I_NEW | I_FREEING)) && !inode_is_locked(inode)); [Thread 2: write-back thread] wb_workfn wb_do_writeback wb_writeback writeback_sb_inodes __writeback_single_inode [WRITE] dirty = inode->i_state & I_DIRTY; I could confirm that the WRITE may happen before and after the READ operation by controlling the timing of the two threads, i.e., by setting breakpoints before the WRITE statement. However, I am not very sure about the implication of such a data race (e.g., causing violations of assumptions). I would appreciate if you could help check on this potential bug and advise whether this is a harmful data race or it is intended. Thank you! -- You are receiving this mail because: You are watching the assignee of the bug.