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=-8.6 required=3.0 tests=DKIMWL_WL_MED,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI, SPF_HELO_NONE,SPF_PASS,URIBL_BLOCKED,USER_IN_DEF_DKIM_WL 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 BCBDBC46460 for ; Sat, 18 May 2019 15:00:53 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id 9122620882 for ; Sat, 18 May 2019 15:00:53 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=google.com header.i=@google.com header.b="vPSmOYQr" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729666AbfERPAw (ORCPT ); Sat, 18 May 2019 11:00:52 -0400 Received: from mail-io1-f65.google.com ([209.85.166.65]:35724 "EHLO mail-io1-f65.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728540AbfERPAw (ORCPT ); Sat, 18 May 2019 11:00:52 -0400 Received: by mail-io1-f65.google.com with SMTP id p2so7802750iol.2 for ; Sat, 18 May 2019 08:00:52 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20161025; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=16Dtq8us2STSS6t8l8g98mqEBDHkTUMHSYlu5UUkqGA=; b=vPSmOYQrmAX9/yD7Q1p7CtitRayTAJednKXbVhCTNNkyK775wgCxuCYUpdEv8a2jTT v+Z7Nz1e+Vej5rXTXmaclDp0KzdviLRDDzphCHDshYDCJNGB2zRh7hCYyoKHqb6+II1C c08LrUkd3u7mNRCYDxaIaZMzeAmli3wvHUkXIbQSrp4A7nDTP9cgHOtpwseo07dcVSA8 4e0GS5KpZVOYscXWEqkplqxojekJciJexLYilxpDVB4sOG9SS3cDdcd7barFca94/7SH LiRE6Bq8mbBZfI6boVvCRiusEL4xQVQVGeyyrIsZD1iLfSo0lX05LaWBVCDX6bZd6DO/ pH3g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:mime-version:references:in-reply-to:from:date :message-id:subject:to:cc; bh=16Dtq8us2STSS6t8l8g98mqEBDHkTUMHSYlu5UUkqGA=; b=Drc0QFOgiNwSH/KB2AGcQRpShf6a1hPOf6hdyL6DXRTonlOa4f8xgf13jesxGEQIci 6CBeUJMedEFNDiIGv0azDkCDIplLo+9Adg0Igp+6t+/FbN785aTgM4IV2HWyNsEzJxE3 5GBY1QKfNrAprxnpjS356gNpuFXx39bdXXFToM5BENzWlkwJ8/oZopOFDZkw/rJGYt68 jJ9WEMI4lNQmZUdH1DMz+20x1BOBWhyX5FOuKVPO+XI15pSvG4M/Z6Gr4tX9Ei54crAU Hf76AYg3MRomqJblT54RhjvBCuoauUME92xgvoK9T4IxNSeNg/gKp06PBRRc3r1aDMCX bv+Q== X-Gm-Message-State: APjAAAUqLlf+eyr2t1BfxT/1JSCXN+gbungHmQuUNDD48mds8ZgSxJfE gfwhjQuW3CTbdNxDUbeN5nlRdyW1hVANfDDdFXxY4g== X-Google-Smtp-Source: APXvYqwBZop9VMj/p+pmsQBemWU77kyYN9I4FWk68o3OV1tLcSw3YE0pk1AYaf5N4PrQDKBZD7vspQbqbOvx05KXems= X-Received: by 2002:a6b:6006:: with SMTP id r6mr3841823iog.231.1558191651264; Sat, 18 May 2019 08:00:51 -0700 (PDT) MIME-Version: 1.0 References: <00000000000014285d05765bf72a@google.com> <0000000000000eaf23058912af14@google.com> <20190517134850.GG17978@ZenIV.linux.org.uk> In-Reply-To: From: Dmitry Vyukov Date: Sat, 18 May 2019 17:00:39 +0200 Message-ID: Subject: Re: BUG: unable to handle kernel paging request in do_mount To: Al Viro Cc: syzbot , linux-fsdevel , LKML , sabin.rapan@gmail.com, syzkaller-bugs Content-Type: text/plain; charset="UTF-8" Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Fri, May 17, 2019 at 4:08 PM Dmitry Vyukov wrote: > > On Fri, May 17, 2019 at 3:48 PM Al Viro wrote: > > > > On Fri, May 17, 2019 at 03:17:02AM -0700, syzbot wrote: > > > This bug is marked as fixed by commit: > > > vfs: namespace: error pointer dereference in do_remount() > > > But I can't find it in any tested tree for more than 90 days. > > > Is it a correct commit? Please update it by replying: > > > #syz fix: exact-commit-title > > > Until then the bug is still considered open and > > > new crashes with the same signature are ignored. > > > > Could somebody explain how the following situation is supposed to > > be handled: > > > > 1) branch B1 with commits C1, C2, C3, C4 is pushed out > > 2) C2 turns out to have a bug, which gets caught and fixed > > 3) fix is folded in and branch B2 with C1, C2', C3', C4' is > > pushed out. The bug is not in it anymore. > > 4) B1 is left mouldering (or is entirely removed); B2 is > > eventually merged into other trees. > > > > This is normal and it appears to be problematic for syzbot. > > How to deal with that? One thing I will *NOT* do in such > > situations is giving up on folding the fixes in. Bisection > > hazards alone make that a bad idea. > > linux-next creates a bit of a havoc. > > The ideal way of handling this is including Tested-by: tag into C2'. > Reported-by: would work too, but people suggested that Reported-by: is > confusing in this situation because it suggests that the commit fixes > a bug in some previous commit. Technically, syzbot now accepts any > tag, so With-inputs-from: > syzbot+73c7fe4f77776505299b@syzkaller.appspotmail.com would work too. > > At this point we obvious can't fix up C2'. For such cases syzbot > accepts #syz fix command to associate bugs with fixes. So replying > with "#syz fix: C2'-commit-title" should do. What is that C2'?