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=-15.8 required=3.0 tests=BAYES_00,DKIM_SIGNED, DKIM_VALID,DKIM_VALID_AU,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_CR_TRAILER, INCLUDES_PATCH,MAILING_LIST_MULTI,SPF_HELO_NONE 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 97402C11F65 for ; Tue, 29 Jun 2021 02:36:59 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [23.128.96.18]) by mail.kernel.org (Postfix) with ESMTP id 79A8B61D08 for ; Tue, 29 Jun 2021 02:36:59 +0000 (UTC) Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S231849AbhF2CjZ (ORCPT ); Mon, 28 Jun 2021 22:39:25 -0400 Received: from mail.kernel.org ([198.145.29.99]:60114 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S231848AbhF2CjZ (ORCPT ); Mon, 28 Jun 2021 22:39:25 -0400 Received: by mail.kernel.org (Postfix) with ESMTPSA id 9B7DE61D07; Tue, 29 Jun 2021 02:36:57 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1624934218; bh=PGH0dS7XtzQQJfpDkXc/Qx/bumd83MEOLPnuYzaVTWo=; h=Date:From:To:Subject:In-Reply-To:From; b=rQfSi5FZTW5Bu42i+T/byWbRnfGgceIb7UFmxAnacBx9ExNhTRyo+egoIh++IwjAf SwDsD+S8BETJCNOOgTj1cJPDn3s1o77Q6BKGSqCpxTlyXbLftsu+mu5LDCXsEgFjh9 Zv4obcotxje+FXIkSy1UiZtyCL9X1OEfQCVwKIdI= Date: Mon, 28 Jun 2021 19:36:57 -0700 From: Andrew Morton To: akpm@linux-foundation.org, alexs@kernel.org, david@redhat.com, dennis@kernel.org, hannes@cmpxchg.org, hughd@google.com, iamjoonsoo.kim@lge.com, linmiaohe@huawei.com, linux-mm@kvack.org, mhocko@suse.com, minchan@kernel.org, mm-commits@vger.kernel.org, richard.weiyang@gmail.com, shy828301@gmail.com, tim.c.chen@linux.intel.com, torvalds@linux-foundation.org, willy@infradead.org, ying.huang@intel.com, yuzhao@google.com Subject: [patch 070/192] mm/shmem: fix shmem_swapin() race with swapoff Message-ID: <20210629023657.aGOursF6g%akpm@linux-foundation.org> In-Reply-To: <20210628193256.008961950a714730751c1423@linux-foundation.org> User-Agent: s-nail v14.8.16 Precedence: bulk Reply-To: linux-kernel@vger.kernel.org List-ID: X-Mailing-List: mm-commits@vger.kernel.org From: Miaohe Lin Subject: mm/shmem: fix shmem_swapin() race with swapoff 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 --- mm/shmem.c | 14 +++++++++++++- 1 file changed, 13 insertions(+), 1 deletion(-) --- a/mm/shmem.c~mm-shmem-fix-shmem_swapin-race-with-swapoff +++ a/mm/shmem.c @@ -1696,7 +1696,8 @@ static int shmem_swapin_page(struct inod 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 inod 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 inod 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; } _