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=-3.5 required=3.0 tests=BAYES_00,DKIM_INVALID, DKIM_SIGNED,HEADER_FROM_DIFFERENT_DOMAINS,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 8530BC2BBD0 for ; Tue, 8 Sep 2020 13:14:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1B8EC23BDE for ; Tue, 8 Sep 2020 13:14:01 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=fail reason="key not found in DNS" (0-bit key) header.d=szeredi.hu header.i=@szeredi.hu header.b="OCx6sLWh" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1729691AbgIHNN5 (ORCPT ); Tue, 8 Sep 2020 09:13:57 -0400 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:40210 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729397AbgIHL0L (ORCPT ); Tue, 8 Sep 2020 07:26:11 -0400 Received: from mail-vs1-xe41.google.com (mail-vs1-xe41.google.com [IPv6:2607:f8b0:4864:20::e41]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 770E4C061573 for ; Tue, 8 Sep 2020 04:26:10 -0700 (PDT) Received: by mail-vs1-xe41.google.com with SMTP id q67so8787020vsd.5 for ; Tue, 08 Sep 2020 04:26:10 -0700 (PDT) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=szeredi.hu; s=google; h=mime-version:references:in-reply-to:from:date:message-id:subject:to :cc; bh=JbwkhwLQx7+GhV9T4X9iG2wrMbFXrQhyeeBQAfsS22c=; b=OCx6sLWhB/bjVTTYCDuEoBWcNogPinb+elYrwkC5IZX4/eTuE9wwCM5CJxd79Vhkon KEnoPdDo6qbSQZ20cg/FVjnX/uiV3PE5flWOCD74O9jp3Fcmgv8zImJom/JS62ZZHtZN XmmtoKu51Jy6QeyhksLLr+K1dMadx4FbJAcoc= 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=JbwkhwLQx7+GhV9T4X9iG2wrMbFXrQhyeeBQAfsS22c=; b=SVQ7cjxg6DWYPwYpbbu1R8R5zkYWUB2dugh0KZ1yPqdB5MCARoxvqjuvxCOBJAnA/C 5g53JpcxkyILIznQYhlNjJTbUKuIVVI6sR2utAKno/mN8ixsN5Zlg5wPEnlbeYYgFHwx maLzLCbu+tbKryt6S8vbARMyrqIXSbEwwPIc+Rp0jG6yNx2z+AklL3yCUObvODc76eHt 4OlkUp0BBn/T3aV6hep/CTakcw/r4GWE5MxyV//zw20eqri/V6OJfmemvfvAmatLmZXW L92asHMWAGKN3ZDRQb+TujG+9+AA2C4gsaciFPkliBLVa1djbLrG17/te2/xMsMWG3FW Pm+g== X-Gm-Message-State: AOAM530+tFhhTXO+cUrqWNPh8OUmQSTx9a4Dw+rTSmMu7142xFxe16mA ob3pU2/PE4e3f6QSwUkR6nIPB14+yK9Z64uBmYSzxQ== X-Google-Smtp-Source: ABdhPJxTfngNoQCIblDdEHyvRzh277qRfyPx6DDR9XF3LO9riGEiL+P5HWvoW3rvgQrzagF/ixhfFISuQK9ZB0LlyuU= X-Received: by 2002:a67:e445:: with SMTP id n5mr14305319vsm.115.1599564369700; Tue, 08 Sep 2020 04:26:09 -0700 (PDT) MIME-Version: 1.0 References: <1599553026-11745-1-git-send-email-pragalla@qti.qualcomm.com> In-Reply-To: <1599553026-11745-1-git-send-email-pragalla@qti.qualcomm.com> From: Miklos Szeredi Date: Tue, 8 Sep 2020 13:25:58 +0200 Message-ID: Subject: Re: [PATCH V4] fuse: Fix VM_BUG_ON_PAGE issue while accessing zero ref count page To: Pradeep P V K Cc: linux-fsdevel@vger.kernel.org, Matthew Wilcox , Sahitya Tummala , sayalil@codeaurora.org, Pradeep P V K Content-Type: text/plain; charset="UTF-8" Sender: linux-fsdevel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org On Tue, Sep 8, 2020 at 10:17 AM Pradeep P V K wrote: > > From: Pradeep P V K > > There is a potential race between fuse_abort_conn() and > fuse_copy_page() as shown below, due to which VM_BUG_ON_PAGE > crash is observed for accessing a free page. > > context#1: context#2: > fuse_dev_do_read() fuse_abort_conn() > ->fuse_copy_args() ->end_requests() This shouldn't happen due to FR_LOCKED logic. Are you seeing this on an upstream kernel? Which version? Thanks, Miklos