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 vger.kernel.org (vger.kernel.org [23.128.96.18]) by smtp.lore.kernel.org (Postfix) with ESMTP id 37456C77B61 for ; Mon, 17 Apr 2023 00:45:44 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S229602AbjDQApd (ORCPT ); Sun, 16 Apr 2023 20:45:33 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:55032 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S229473AbjDQApb (ORCPT ); Sun, 16 Apr 2023 20:45:31 -0400 Received: from mail-yb1-xb35.google.com (mail-yb1-xb35.google.com [IPv6:2607:f8b0:4864:20::b35]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 38E40211C for ; Sun, 16 Apr 2023 17:45:30 -0700 (PDT) Received: by mail-yb1-xb35.google.com with SMTP id k39so2337974ybj.8 for ; Sun, 16 Apr 2023 17:45:30 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=google.com; s=20221208; t=1681692329; x=1684284329; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:from:to:cc:subject:date:message-id:reply-to; bh=kRSWS4CahJKmzHjoYHWbTfAxUOlWiKT6IkxMS+a7Rf8=; b=sbBQCkJR1blA3hV96FpkODzI2tgHmoZZfsnImeAQnIAhG79OWScwEEOSM7gZ0tW1zP EiFVqszySsbrwI59L7OFeP55CYduW/jOtunH0hxePs7wY85uyAz1iH6Psg+xzgzCTdJP 0iKpt8nOteMGmwrsWscYZCyPD7u3VlJlygy12rXWVMHcJrTq2W+1vrdcs10Wt6OwCjdE M+EdvAlQBCbLcihbX/qL6yLRDRSeNVnfgNOXMliL4e6yduDQYHOIvj2fqlHsdTnTpWXF WgNHZPbRajqpfbbBq+Hfue3QT3sz1wqUAeDEzHKSe+xpwUMW+mWmOvKYuOx14RDBvnnl wwcg== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20221208; t=1681692329; x=1684284329; h=mime-version:references:message-id:in-reply-to:subject:cc:to:from :date:x-gm-message-state:from:to:cc:subject:date:message-id:reply-to; bh=kRSWS4CahJKmzHjoYHWbTfAxUOlWiKT6IkxMS+a7Rf8=; b=ljxiNmOOQDqfHNYjpUOpmIGVorOv/bBb3wg3wuQkUHsr33Ncds1MsJAQAA+uJkxaGK 84humSnrSHqLQp5U0Jesgrel42V3Ix6VTkNJveaNwaPMhoB814CmdxJLIS0gk/4srVKC hOVr2z9fzNA0Hnax6H2o1bahmNgUBALzLJM3LJgUvJZxUa0QiAYFYJfHN5d5Pp8cDa1A OHeJsPNAqJuF6HGL4U5mSVTJsvoW9fw8vzLbNp9njDxH/bx5FxpZ+PB8mpVI8e2ij/Hi igN3h0a5Q9256k9M4Xj2FIGK4SlBq9uXVY8iLw8omU+avJ094KS9PUkXviaIN+PXSr+3 pMLQ== X-Gm-Message-State: AAQBX9f6bkcF6VN+U8bO+vH5SC0oXxLj3M9AcIjVNLhpGgSdPCqlLQGT meB87/Nb6DFJGXIke4CXxSVStw== X-Google-Smtp-Source: AKy350ZNiO/Qqw4kBjaaCtnr795xEsGikp7UxElEWMXA54ObhUZJ121qoa5BUfup+ExOJL25sSjdBQ== X-Received: by 2002:a05:6902:114d:b0:b6a:9364:1dc8 with SMTP id p13-20020a056902114d00b00b6a93641dc8mr15325573ybu.44.1681692329122; Sun, 16 Apr 2023 17:45:29 -0700 (PDT) Received: from ripple.attlocal.net (172-10-233-147.lightspeed.sntcca.sbcglobal.net. [172.10.233.147]) by smtp.gmail.com with ESMTPSA id be18-20020a05690c009200b0054fcbf35b94sm2601627ywb.87.2023.04.16.17.45.27 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sun, 16 Apr 2023 17:45:28 -0700 (PDT) Date: Sun, 16 Apr 2023 17:45:18 -0700 (PDT) From: Hugh Dickins X-X-Sender: hugh@ripple.attlocal.net To: Andrew Morton cc: Zach O'Keefe , Yang Shi , Ivan Orlov , himadrispandya@gmail.com, linux-kernel@vger.kernel.org, linux-kernel-mentees@lists.linuxfoundation.org, linux-mm@kvack.org, skhan@linuxfoundation.org, syzbot+9578faa5475acb35fa50@syzkaller.appspotmail.com, Mike Kravetz , "Kirill A. Shutemov" , Matthew Wilcox Subject: Re: [PATCH v2] mm: khugepaged: Fix kernel BUG in hpage_collapse_scan_file In-Reply-To: <20230416113335.caeafda1328fdd4bfe2406e8@linux-foundation.org> Message-ID: References: <20230330155305.423051-1-ivan.orlov0322@gmail.com> <20230331013301.ecgkjymaf3ws6rfb@google.com> <20230416113335.caeafda1328fdd4bfe2406e8@linux-foundation.org> MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Sun, 16 Apr 2023, Andrew Morton wrote: > > Circling back to this fix... > > The BUG() is obviously real. It's worth remembering that syzbot's reproducer involves artificially injecting page allocation failures. So although the bug may be "real", it is rather in the theoretical category, way down on my own list to look at, and I'd say not at all urgent to fix. Hugh > We're unsure that Ivan's fix is the best > one. We haven't identified a Fixes:, and as this report is against the 6.2 > kernel, a cc:stable will be needed. > > According to the sysbot bisection > (https://syzkaller.appspot.com/bug?id=7d6bb3760e026ece7524500fe44fb024a0e959fc), > this is present in linux-5.19, so it might predate Zach's > 58ac9a8993a13ebc changes. But that bisection claim might be > misleading. > > And Zach is offline for a few months. So can people please take a look > and see if we can get this wrapped up? > > Matthew, the assertion failure is in the > > VM_BUG_ON(index != xas.xa_index); > > which was added in 77da9389b9d5f, so perhaps you could take a look? > > Thanks.