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=-6.8 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,MAILING_LIST_MULTI,SIGNED_OFF_BY, SPF_PASS,URIBL_BLOCKED,USER_AGENT_GIT 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 2A93FC43387 for ; Tue, 15 Jan 2019 16:39:33 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id E32F920859 for ; Tue, 15 Jan 2019 16:39:32 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547570373; bh=sCXDiBO19Cef8htAnAM9I2796qaLC3B87m2G038gy2g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:List-ID:From; b=qGXktcbvmYeOrHlaoKUQKAlW9LItFvp5bxoD/wJDMe6BLr8bw/8uBFepea5yszHrR q7psp+0lV+5h+Wq26nO+2ARnD1BVO0fP6J6RJnasqC4OlZVYUXdFwYzbcZRqTAGPn1 6dr1t7KbPHBSuNP+46Mr4d8ucH+QBNaZZO42iPr4= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1732369AbfAOQjc (ORCPT ); Tue, 15 Jan 2019 11:39:32 -0500 Received: from mail.kernel.org ([198.145.29.99]:55570 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1732346AbfAOQj0 (ORCPT ); Tue, 15 Jan 2019 11:39:26 -0500 Received: from localhost (5356596B.cm-6-7b.dynamic.ziggo.nl [83.86.89.107]) (using TLSv1.2 with cipher ECDHE-RSA-AES256-GCM-SHA384 (256/256 bits)) (No client certificate requested) by mail.kernel.org (Postfix) with ESMTPSA id EC0A82054F; Tue, 15 Jan 2019 16:39:24 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1547570365; bh=sCXDiBO19Cef8htAnAM9I2796qaLC3B87m2G038gy2g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=IvVIYYMTWp2lPfGMcg+AUdgfsLGA5zA3W08KFlqHLOPGLL4FH72VddFJ0ZxHBWMYP RpDKW4KCPEIVzh6TerrB2m1xFJ/rvZzgAo+4vbUnCKlsnuezjAj0LR2FFzOu6q3vXj pCtIRM0+EJwYyTyIpNyxaCk50Naer2R/20sVymv8= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Theodore Tso , stable@kernel.org Subject: [PATCH 4.9 14/16] ext4: fix a potential fiemap/page fault deadlock w/ inline_data Date: Tue, 15 Jan 2019 17:35:57 +0100 Message-Id: <20190115154849.886322430@linuxfoundation.org> X-Mailer: git-send-email 2.20.1 In-Reply-To: <20190115154848.164648613@linuxfoundation.org> References: <20190115154848.164648613@linuxfoundation.org> User-Agent: quilt/0.65 X-stable: review X-Patchwork-Hint: ignore MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 8bit Sender: linux-kernel-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 4.9-stable review patch. If anyone has any objections, please let me know. ------------------ From: Theodore Ts'o commit 2b08b1f12cd664dc7d5c84ead9ff25ae97ad5491 upstream. The ext4_inline_data_fiemap() function calls fiemap_fill_next_extent() while still holding the xattr semaphore. This is not necessary and it triggers a circular lockdep warning. This is because fiemap_fill_next_extent() could trigger a page fault when it writes into page which triggers a page fault. If that page is mmaped from the inline file in question, this could very well result in a deadlock. This problem can be reproduced using generic/519 with a file system configuration which has the inline_data feature enabled. Signed-off-by: Theodore Ts'o Cc: stable@kernel.org Signed-off-by: Greg Kroah-Hartman --- fs/ext4/inline.c | 6 +++--- 1 file changed, 3 insertions(+), 3 deletions(-) --- a/fs/ext4/inline.c +++ b/fs/ext4/inline.c @@ -1859,12 +1859,12 @@ int ext4_inline_data_fiemap(struct inode physical += (char *)ext4_raw_inode(&iloc) - iloc.bh->b_data; physical += offsetof(struct ext4_inode, i_block); - if (physical) - error = fiemap_fill_next_extent(fieinfo, start, physical, - inline_len, flags); brelse(iloc.bh); out: up_read(&EXT4_I(inode)->xattr_sem); + if (physical) + error = fiemap_fill_next_extent(fieinfo, start, physical, + inline_len, flags); return (error < 0 ? error : 0); }