From patchwork Mon Jul 12 06:07:11 2021 Content-Type: text/plain; charset="utf-8" MIME-Version: 1.0 Content-Transfer-Encoding: 7bit X-Patchwork-Submitter: Greg Kroah-Hartman X-Patchwork-Id: 475748 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=-19.4 required=3.0 tests=BAYES_00,DKIMWL_WL_HIGH, DKIM_SIGNED,DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS, INCLUDES_CR_TRAILER, INCLUDES_PATCH, MAILING_LIST_MULTI, SPF_HELO_NONE, 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 368F6C07E9B for ; Mon, 12 Jul 2021 07:13:32 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 1D2A06143D for ; Mon, 12 Jul 2021 07:13:32 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S242188AbhGLHQS (ORCPT ); Mon, 12 Jul 2021 03:16:18 -0400 Received: from mail.kernel.org ([198.145.29.99]:47878 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S240764AbhGLHPR (ORCPT ); Mon, 12 Jul 2021 03:15:17 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 971A16140A; Mon, 12 Jul 2021 07:11:51 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linuxfoundation.org; s=korg; t=1626073912; bh=bSWK8wU7FX6faaFnh137nVGMdgTSppAImlz6drdSNmU=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=Etke5UF97eQgDbvRYDWsHp/UEX32VrtTNVdEolNjrjnYP4Fkvb5QZ5jWJCA9LONSr lJHRFTSVHeXCJU/4IRZosjBAwn3Vz+/2gJ91IjpLNRF35ihurv1xai4LackELT5HXj eM8ocqbmxswdx3MI+5NKpEz0xXGUctYUZ7NtNivc= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Miaohe Lin , "Huang, Ying" , Dennis Zhou , Tim Chen , Hugh Dickins , Johannes Weiner , Michal Hocko , Joonsoo Kim , Alex Shi , Matthew Wilcox , Minchan Kim , Wei Yang , Yang Shi , David Hildenbrand , Yu Zhao , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 5.12 348/700] mm/shmem: fix shmem_swapin() race with swapoff Date: Mon, 12 Jul 2021 08:07:11 +0200 Message-Id: <20210712061013.325433186@linuxfoundation.org> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20210712060924.797321836@linuxfoundation.org> References: <20210712060924.797321836@linuxfoundation.org> User-Agent: quilt/0.66 MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: stable@vger.kernel.org From: Miaohe Lin [ Upstream commit 2efa33fc7f6ec94a3a538c1a264273c889be2b36 ] When I was investigating the swap code, I found the below possible race window: CPU 1 CPU 2 ----- ----- shmem_swapin swap_cluster_readahead if (likely(si->flags & (SWP_BLKDEV | SWP_FS_OPS))) { swapoff .. si->swap_file = NULL; .. struct inode *inode = si->swap_file->f_mapping->host;[oops!] Close this race window by using get/put_swap_device() to guard against concurrent swapoff. Link: https://lkml.kernel.org/r/20210426123316.806267-5-linmiaohe@huawei.com Fixes: 8fd2e0b505d1 ("mm: swap: check if swap backing device is congested or not") Signed-off-by: Miaohe Lin Reviewed-by: "Huang, Ying" Cc: Dennis Zhou Cc: Tim Chen Cc: Hugh Dickins Cc: Johannes Weiner Cc: Michal Hocko Cc: Joonsoo Kim Cc: Alex Shi Cc: Matthew Wilcox Cc: Minchan Kim Cc: Wei Yang Cc: Yang Shi Cc: David Hildenbrand Cc: Yu Zhao Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/shmem.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) diff --git a/mm/shmem.c b/mm/shmem.c index 6e99a4ad6e1f..1a03744240e7 100644 --- a/mm/shmem.c +++ b/mm/shmem.c @@ -1696,7 +1696,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, struct address_space *mapping = inode->i_mapping; struct shmem_inode_info *info = SHMEM_I(inode); struct mm_struct *charge_mm = vma ? vma->vm_mm : current->mm; - struct page *page; + struct swap_info_struct *si; + struct page *page = NULL; swp_entry_t swap; int error; @@ -1704,6 +1705,12 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, swap = radix_to_swp_entry(*pagep); *pagep = NULL; + /* Prevent swapoff from happening to us. */ + si = get_swap_device(swap); + if (!si) { + error = EINVAL; + goto failed; + } /* Look it up and read it in.. */ page = lookup_swap_cache(swap, NULL, 0); if (!page) { @@ -1765,6 +1772,8 @@ static int shmem_swapin_page(struct inode *inode, pgoff_t index, swap_free(swap); *pagep = page; + if (si) + put_swap_device(si); return 0; failed: if (!shmem_confirm_swap(mapping, index, swap)) @@ -1775,6 +1784,9 @@ unlock: put_page(page); } + if (si) + put_swap_device(si); + return error; }