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 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 76BF6C43460 for ; Fri, 2 Apr 2021 13:27:45 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id D05786112E for ; Fri, 2 Apr 2021 13:27:44 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org D05786112E Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=infradead.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=owner-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix) id 3969B6B0072; Fri, 2 Apr 2021 09:27:44 -0400 (EDT) Received: by kanga.kvack.org (Postfix, from userid 40) id 343FF6B0073; Fri, 2 Apr 2021 09:27:44 -0400 (EDT) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 20D9A6B0074; Fri, 2 Apr 2021 09:27:44 -0400 (EDT) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0054.hostedemail.com [216.40.44.54]) by kanga.kvack.org (Postfix) with ESMTP id 07BE86B0072 for ; Fri, 2 Apr 2021 09:27:44 -0400 (EDT) Received: from smtpin21.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay04.hostedemail.com (Postfix) with ESMTP id B6747B9F5 for ; Fri, 2 Apr 2021 13:27:43 +0000 (UTC) X-FDA: 77987504406.21.6682CFC Received: from casper.infradead.org (casper.infradead.org [90.155.50.34]) by imf08.hostedemail.com (Postfix) with ESMTP id 1B56380192D8 for ; Fri, 2 Apr 2021 13:27:40 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; q=dns/txt; c=relaxed/relaxed; d=infradead.org; s=casper.20170209; h=In-Reply-To:Content-Type:MIME-Version: References:Message-ID:Subject:Cc:To:From:Date:Sender:Reply-To: Content-Transfer-Encoding:Content-ID:Content-Description; bh=Quv+d5ruToqASsYHkDYyM+RNKRKLkPKY2MzE/OEcBCc=; b=Hn4p16U0Xxhq5upbBRvlz8n2ox zWm3vcPITR6WIgIRjEtrgfbpywR54mfRiOw1cS0cS9diYxrum7asLMiUvNEtR/bUQa9suts9rquNt 6h5DAKJQR8mxrMOT6YRTTRA2o9i73/i4wO3P43uXwZ/0kXaIRnEjeWSgQwXrfi/N/LUHpJalqporl HfQAdmqsnJh/m1SlQtGsDDjmv81jNN5D6vhUhWLtxaZyNq1MxY3XN5tDgMXYqNBQBTO9ljSjUqaFY pP5P053z76nhNadrx0wLL6GPQXV/dEzbk9NmQ68ylZ8oFQW2QYwjZRVpLURl9rRZnVeP4iXMTBLn+ cRrcvYcA==; Received: from willy by casper.infradead.org with local (Exim 4.94 #2 (Red Hat Linux)) id 1lSJpM-007gLj-Br; Fri, 02 Apr 2021 13:27:14 +0000 Date: Fri, 2 Apr 2021 14:27:08 +0100 From: Matthew Wilcox To: Hugh Dickins Cc: Andrew Morton , linux-mm@kvack.org, linux-fsdevel@vger.kernel.org, linux-nvdimm@lists.01.org, linux-kernel@vger.kernel.org Subject: Re: BUG_ON(!mapping_empty(&inode->i_data)) Message-ID: <20210402132708.GM351017@casper.infradead.org> References: <20210331024913.GS351017@casper.infradead.org> <20210401170615.GH351017@casper.infradead.org> <20210402031305.GK351017@casper.infradead.org> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20210402031305.GK351017@casper.infradead.org> X-Rspamd-Server: rspam01 X-Rspamd-Queue-Id: 1B56380192D8 X-Stat-Signature: scex7mgmk6gm5mnn9hgdung38oyfc7b4 Received-SPF: none (infradead.org>: No applicable sender policy available) receiver=imf08; identity=mailfrom; envelope-from=""; helo=casper.infradead.org; client-ip=90.155.50.34 X-HE-DKIM-Result: pass/pass X-HE-Tag: 1617370060-470318 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Fri, Apr 02, 2021 at 04:13:05AM +0100, Matthew Wilcox wrote: > + for (;;) { > + xas_load(xas); > + if (!xas_is_node(xas)) > + break; > + xas_delete_node(xas); > + xas->xa_index -= XA_CHUNK_SIZE; > + if (xas->xa_index < index) > + break; That's a bug. index can be 0, so the condition would never be true. It should be: if (xas->xa_index <= (index | XA_CHUNK_MASK)) break; xas->xa_index -= XA_CHUNK_SIZE; The test doesn't notice this bug because the tree is otherwise empty, and the !xas_is_node(xas) condition is hit first. The next test will notice this.