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=-6.6 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,FREEMAIL_FORGED_FROMDOMAIN,FREEMAIL_FROM, HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SPF_HELO_NONE,SPF_PASS, USER_AGENT_GIT 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 DCC3FC2D0A3 for ; Wed, 4 Nov 2020 01:20:34 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 9C4842242C for ; Wed, 4 Nov 2020 01:20:34 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (2048-bit key) header.d=gmail.com header.i=@gmail.com header.b="aq1E5K6k" Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1730335AbgKDBUe (ORCPT ); Tue, 3 Nov 2020 20:20:34 -0500 Received: from lindbergh.monkeyblade.net ([23.128.96.19]:36118 "EHLO lindbergh.monkeyblade.net" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1729246AbgKDBUd (ORCPT ); Tue, 3 Nov 2020 20:20:33 -0500 Received: from mail-pg1-x542.google.com (mail-pg1-x542.google.com [IPv6:2607:f8b0:4864:20::542]) by lindbergh.monkeyblade.net (Postfix) with ESMTPS id 590C8C040203 for ; Tue, 3 Nov 2020 17:20:32 -0800 (PST) Received: by mail-pg1-x542.google.com with SMTP id o3so15115415pgr.11 for ; Tue, 03 Nov 2020 17:20:32 -0800 (PST) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=gmail.com; s=20161025; h=from:to:cc:subject:date:message-id:in-reply-to:references; bh=Hvt5hI7HDdctAK55bNYHJ4XmctT+HEghDbdMAXPbZ5g=; b=aq1E5K6kmU0nnjzsWI1rt2Va0QbZ4Ji0niXipuJ5JAyVE6NWm1egHASx7hciZfzlqS WFzJyG+PPERqUOm3Cpq4u+lbuXqmVNltCsiw9tPfOHQIHqJBnm3oDgCGBqC2ROBEbVaW Dr4cC3+gqfWJ5XT+cy1v/Nys0JxqFwmZBwCspAPzJ/8RgEjOMzEHJShTlTXQ2wGijcgi DFOWC6qjRgTZA4dorxFY2lUe6Yyd3gkRXn7XDDLjJDej8ZG/Wnem5lNkRL5ka7ZAqebX wa/hq9AkNWBvT5yRLe1H6RwZU8+Xyu8Ww3B73YJEL4QPUXg5C19vpIlgAbM+rpyIjjIK JT2g== X-Google-DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d=1e100.net; s=20161025; h=x-gm-message-state:from:to:cc:subject:date:message-id:in-reply-to :references; bh=Hvt5hI7HDdctAK55bNYHJ4XmctT+HEghDbdMAXPbZ5g=; b=N0oZocih/YX7L4DYLX9AVdPDvFi5BYWsqupR6Pr/Gof7TjvCbN8GYhnWD6mf8Tuen9 +vyu7tllTBfXoTivsKeghoootSZPXGw9EnWBuo6w3DTW9eWEY8408gPKNlMSqGsAE7iJ C1Yrh6QVLpo1Nol/WoI7BNSDgj26+tAfJ6d9bbHM3lL33QY9xYAjDZqigtPTy4eJqSWq luaYHT62gXcxtSMcrZ45PN7+8DoBcwnWPy+19jXykOuVTf4XJSeMDLQu8ynkv/Hx4QnH r8eD3m3nivK9JfNxSGyYYom+42yT8PT1JCPH0c9cnuu/YUsw0G07kGvwXH5Mm9hMLLyu Achg== X-Gm-Message-State: AOAM533WN2Dt23h5YWUy4CmZvsYeZQSOiA7+E22NrTyaycR272CfZ5mL fLZGM2QimOxNe7PM4lNYo7w= X-Google-Smtp-Source: ABdhPJw6Pl73jkTlMTonNNuU+/cQ5qa9lh3QwW74KxYvv8py0F5+EQ1WCskUYGT0hBbMUIPaUEV0eA== X-Received: by 2002:a63:6c09:: with SMTP id h9mr18712465pgc.214.1604452831915; Tue, 03 Nov 2020 17:20:31 -0800 (PST) Received: from DESKTOP-P2JGRFE.localdomain ([1.234.114.36]) by smtp.gmail.com with ESMTPSA id w131sm346176pfd.14.2020.11.03.17.20.29 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Tue, 03 Nov 2020 17:20:31 -0800 (PST) From: Wonhuyk Yang To: willy@infradead.org Cc: akpm@linux-foundation.org, linux-fsdevel@vger.kernel.org, miklos@szeredi.hu, vvghjk1234@gmail.com Subject: Re: [PATCH] fuse: fix panic in __readahead_batch() Date: Wed, 4 Nov 2020 10:20:17 +0900 Message-Id: <20201104012017.19311-1-vvghjk1234@gmail.com> X-Mailer: git-send-email 2.17.1 In-Reply-To: <20201103143828.GU27442@casper.infradead.org> References: <20201103143828.GU27442@casper.infradead.org> Precedence: bulk List-ID: X-Mailing-List: linux-fsdevel@vger.kernel.org From: Wonhyuk Yang Thank you for your reply. > By the way, this isn't right. You meant 'if (xa_is_value(page))'. I think you missed a ! operator. Actually I was not sure that there are other internal entries except retry entry and zero entry in the xas_for_each(). > The reason we can see a retry entry here is that we did a readahead of a > single page at index 0. Between that page being inserted and the lookup, > another page was removed from the file (maybe the file was truncated > down) and this caused the node to be removed, and the pointer to the > page got moved into the root of the tree. The pointer in the node was > replaced with a retry entry, indicating that the page is still valid, > it just isn't here any more. And so we retry the lookup. It's a little difficult for me, but thank you for your specific explanation.