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_PASS autolearn=ham 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 B5BB7C282C3 for ; Thu, 24 Jan 2019 03:41:05 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 8E93C2184B for ; Thu, 24 Jan 2019 03:41:05 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727318AbfAXDkU convert rfc822-to-8bit (ORCPT ); Wed, 23 Jan 2019 22:40:20 -0500 Received: from mail.wl.linuxfoundation.org ([198.145.29.98]:47940 "EHLO mail.wl.linuxfoundation.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727302AbfAXDkT (ORCPT ); Wed, 23 Jan 2019 22:40:19 -0500 Received: from mail.wl.linuxfoundation.org (localhost [127.0.0.1]) by mail.wl.linuxfoundation.org (Postfix) with ESMTP id 708A52DCC5 for ; Thu, 24 Jan 2019 03:40:18 +0000 (UTC) Received: by mail.wl.linuxfoundation.org (Postfix, from userid 486) id 6F1482DEA4; Thu, 24 Jan 2019 03:40:18 +0000 (UTC) From: bugzilla-daemon@bugzilla.kernel.org To: linux-ext4@vger.kernel.org Subject: [Bug 201631] WARNING: CPU: 11 PID: 29593 at fs/ext4/inode.c:3927 .ext4_set_page_dirty+0x70/0xb0 Date: Thu, 24 Jan 2019 03:40:18 +0000 X-Bugzilla-Reason: None X-Bugzilla-Type: changed 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: aneesh.kumar@linux.ibm.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: Message-ID: In-Reply-To: References: 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 X-Virus-Scanned: ClamAV using ClamSMTP 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=201631 --- Comment #50 from Aneesh Kumar KV (aneesh.kumar@linux.ibm.com) --- (In reply to Jan Kara from comment #47) > OK, so it seems to be more and more clear that PPC indeed has some race in > page table updates. What I can see in the latest report is: > > Clean page (index 92, ino 681741, i_size 828368, flags 7fff0000002016, > mapcount 1) with dirty PTE (pte_val c0000005f7fae186) on unmap! Vma flags > fb, pgoff 0, file ino 681741 > ... > page 92: b_state 21, b_blocknr 2801084, b_mapped 1452389112002, b_mapped2 0, > b_cleaned 1452396217779, now 1452400395514 > > So "Vma flags fb" shows its a normal shared, writeable file mapping. Page is > somewhere in the middle of the file (file size is 828368, page is at offset > 376832). The page has been writeably mapped 11ms ago (you are using ext2 > filesystem which was confusing my previous debug attempts so only this one > has shown proper times) and written back 4ms ago (which should have > writeprotected the pte) but we still have writeable pte now on which the > assertion hits. So either page_mkclean() failed to clear the PTE or someone > created new writeable PTE without telling ext4. > > I'll attach a new version of debug patch to distinguish these two cases. The fact that we did try to write out the page at (bh_cleaned 1452396217779)implies we should have cleared the _PAGE_WRITE bit right (clear_page_dirty_for_io())? So we should either find that bit cleared in pte (if we missed a related tlb flush and tlb still has that pte with _PAGE_WRITE) or we find that set. In this case, we find _PAGE_WRITE set in the pte during zap. Does that imply we did call finish_fault()? which should have ideally resulted in we calling page_mkwrite(). I am still not clear what could be a possible race that can result in this? -aneesh -- You are receiving this mail because: You are watching the assignee of the bug.