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,INCLUDES_PATCH,MAILING_LIST_MULTI, SIGNED_OFF_BY,SPF_HELO_NONE,SPF_PASS 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 D1CEEC35250 for ; Sun, 9 Feb 2020 12:58:01 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id A354420733 for ; Sun, 9 Feb 2020 12:58:01 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1581253081; bh=42Toa0wCm64lMlBaZOO262JEMVC8hnKSYSoi3jUDqaE=; h=Subject:To:Cc:From:Date:List-ID:From; b=jS6RSwFQfyweP0+Lt0rVwICb2jzHw3rEyFU9fxVA/81RrjTJ3AIZIWnb+joCJ0i/d rkdVn5fI3Ua4oBSG7YitLty0OG+7qLJtIvBpYL4ZlC5NPqKYEy9KYgWot3NyhuV7g8 wUm4pyaCKvll5gzkb/cnlsucAecvQfxnNSwkJM8Q= Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1727514AbgBIM6B (ORCPT ); Sun, 9 Feb 2020 07:58:01 -0500 Received: from out5-smtp.messagingengine.com ([66.111.4.29]:49727 "EHLO out5-smtp.messagingengine.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1727710AbgBIM6B (ORCPT ); Sun, 9 Feb 2020 07:58:01 -0500 Received: from compute6.internal (compute6.nyi.internal [10.202.2.46]) by mailout.nyi.internal (Postfix) with ESMTP id C376721C1C; Sun, 9 Feb 2020 07:57:59 -0500 (EST) Received: from mailfrontend1 ([10.202.2.162]) by compute6.internal (MEProxy); Sun, 09 Feb 2020 07:57:59 -0500 DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=cc:content-transfer-encoding:content-type :date:from:message-id:mime-version:subject:to:x-me-proxy :x-me-proxy:x-me-sender:x-me-sender:x-sasl-enc; s=fm2; bh=lJRUt0 GvLSCb1jChjldK5+42MgMIm1sieOvxDu8DZHA=; b=fmUs8vGvVHsvXv/grlaDOa sei357p6+soBRFKVE9JIw44y5SSrv7jHL8eJFEr04d1DqM5N9wCegGL/UDk+UncC 1dCL3xG0I7GTPo2Tj/FGIPZJ35AcZi2DQw3MuLIQ/QawD6B/CM9t8PZAg12MhDkq mgeIyEMCIjOTuU2OkHbLjxxtd800byzw+yqwHdNomIIUqT3bEI3i7TZxVNb7kpF+ Khk1un6gdn4WQbn9HuA7kFNaGeKpkTbYVASKCXrbfSJaleS1ABzeLBlZlIQ7Nvuo HrldfIItJFuke1lJKc438Li4WicmMDGWLWWg/2YfMevJ8fBn4kx03bMGUlOruOTQ == X-ME-Sender: X-ME-Proxy-Cause: gggruggvucftvghtrhhoucdtuddrgedugedrheelgddvfecutefuodetggdotefrodftvf curfhrohhfihhlvgemucfhrghsthforghilhdpqfgfvfdpuffrtefokffrpgfnqfghnecu uegrihhlohhuthemuceftddtnecunecujfgurhepuffvhfffkfggtgfgsehtkeertddttd flnecuhfhrohhmpeeoghhrvghgkhhhsehlihhnuhigfhhouhhnuggrthhiohhnrdhorhhg qeenucffohhmrghinhepkhgvrhhnvghlrdhorhhgnecukfhppeefkedrleekrdefjedrud efheenucevlhhushhtvghrufhiiigvpedtnecurfgrrhgrmhepmhgrihhlfhhrohhmpehg rhgvgheskhhrohgrhhdrtghomh X-ME-Proxy: Received: from localhost (unknown [38.98.37.135]) by mail.messagingengine.com (Postfix) with ESMTPA id 94D54328005A; Sun, 9 Feb 2020 07:57:58 -0500 (EST) Subject: FAILED: patch "[PATCH] ext4: fix deadlock allocating crypto bounce page from mempool" failed to apply to 4.4-stable tree To: ebiggers@google.com, tytso@mit.edu Cc: From: Date: Sun, 09 Feb 2020 12:25:55 +0100 Message-ID: <1581247555171234@kroah.com> MIME-Version: 1.0 Content-Type: text/plain; charset=ANSI_X3.4-1968 Content-Transfer-Encoding: 8bit Sender: stable-owner@vger.kernel.org Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org The patch below does not apply to the 4.4-stable tree. If someone wants it applied there, or to any other stable or longterm tree, then please email the backport, including the original git commit id to . thanks, greg k-h ------------------ original commit in Linus's tree ------------------ >From 547c556f4db7c09447ecf5f833ab6aaae0c5ab58 Mon Sep 17 00:00:00 2001 From: Eric Biggers Date: Tue, 31 Dec 2019 12:11:49 -0600 Subject: [PATCH] ext4: fix deadlock allocating crypto bounce page from mempool ext4_writepages() on an encrypted file has to encrypt the data, but it can't modify the pagecache pages in-place, so it encrypts the data into bounce pages and writes those instead. All bounce pages are allocated from a mempool using GFP_NOFS. This is not correct use of a mempool, and it can deadlock. This is because GFP_NOFS includes __GFP_DIRECT_RECLAIM, which enables the "never fail" mode for mempool_alloc() where a failed allocation will fall back to waiting for one of the preallocated elements in the pool. But since this mode is used for all a bio's pages and not just the first, it can deadlock waiting for pages already in the bio to be freed. This deadlock can be reproduced by patching mempool_alloc() to pretend that pool->alloc() always fails (so that it always falls back to the preallocations), and then creating an encrypted file of size > 128 KiB. Fix it by only using GFP_NOFS for the first page in the bio. For subsequent pages just use GFP_NOWAIT, and if any of those fail, just submit the bio and start a new one. This will need to be fixed in f2fs too, but that's less straightforward. Fixes: c9af28fdd449 ("ext4 crypto: don't let data integrity writebacks fail with ENOMEM") Cc: stable@vger.kernel.org Signed-off-by: Eric Biggers Link: https://lore.kernel.org/r/20191231181149.47619-1-ebiggers@kernel.org Signed-off-by: Theodore Ts'o diff --git a/fs/ext4/page-io.c b/fs/ext4/page-io.c index 24aeedb8fc75..68b39e75446a 100644 --- a/fs/ext4/page-io.c +++ b/fs/ext4/page-io.c @@ -512,17 +512,26 @@ int ext4_bio_write_page(struct ext4_io_submit *io, gfp_t gfp_flags = GFP_NOFS; unsigned int enc_bytes = round_up(len, i_blocksize(inode)); + /* + * Since bounce page allocation uses a mempool, we can only use + * a waiting mask (i.e. request guaranteed allocation) on the + * first page of the bio. Otherwise it can deadlock. + */ + if (io->io_bio) + gfp_flags = GFP_NOWAIT | __GFP_NOWARN; retry_encrypt: bounce_page = fscrypt_encrypt_pagecache_blocks(page, enc_bytes, 0, gfp_flags); if (IS_ERR(bounce_page)) { ret = PTR_ERR(bounce_page); - if (ret == -ENOMEM && wbc->sync_mode == WB_SYNC_ALL) { - if (io->io_bio) { + if (ret == -ENOMEM && + (io->io_bio || wbc->sync_mode == WB_SYNC_ALL)) { + gfp_flags = GFP_NOFS; + if (io->io_bio) ext4_io_submit(io); - congestion_wait(BLK_RW_ASYNC, HZ/50); - } - gfp_flags |= __GFP_NOFAIL; + else + gfp_flags |= __GFP_NOFAIL; + congestion_wait(BLK_RW_ASYNC, HZ/50); goto retry_encrypt; }