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[23.128.96.18]) by mx.google.com with ESMTP id hr13si9430206ejc.666.2021.10.25.02.26.41; Mon, 25 Oct 2021 02:27:07 -0700 (PDT) Received-SPF: pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) client-ip=23.128.96.18; Authentication-Results: mx.google.com; spf=pass (google.com: domain of linux-kernel-owner@vger.kernel.org designates 23.128.96.18 as permitted sender) smtp.mailfrom=linux-kernel-owner@vger.kernel.org; dmarc=fail (p=NONE sp=NONE dis=NONE) header.from=alibaba.com Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S232525AbhJYJYO (ORCPT + 99 others); Mon, 25 Oct 2021 05:24:14 -0400 Received: from out30-43.freemail.mail.aliyun.com ([115.124.30.43]:35893 "EHLO out30-43.freemail.mail.aliyun.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S232371AbhJYJYE (ORCPT ); Mon, 25 Oct 2021 05:24:04 -0400 X-Alimail-AntiSpam: AC=PASS;BC=-1|-1;BR=01201311R731e4;CH=green;DM=||false|;DS=||;FP=0|-1|-1|-1|0|-1|-1|-1;HT=e01e04357;MF=rongwei.wang@linux.alibaba.com;NM=1;PH=DS;RN=9;SR=0;TI=SMTPD_---0UtZwp5E_1635153697; Received: from localhost.localdomain(mailfrom:rongwei.wang@linux.alibaba.com fp:SMTPD_---0UtZwp5E_1635153697) by smtp.aliyun-inc.com(127.0.0.1); Mon, 25 Oct 2021 17:21:39 +0800 From: Rongwei Wang To: akpm@linux-foundation.org, willy@infradead.org, song@kernel.org, william.kucharski@oracle.com, hughd@google.com, shy828301@gmail.com Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: [PATCH 2/2] mm, thp: fix incorrect unmap behavior for private pages Date: Mon, 25 Oct 2021 17:21:34 +0800 Message-Id: <20211025092134.18562-3-rongwei.wang@linux.alibaba.com> X-Mailer: git-send-email 2.32.0 In-Reply-To: <20211025092134.18562-1-rongwei.wang@linux.alibaba.com> References: <20211025092134.18562-1-rongwei.wang@linux.alibaba.com> MIME-Version: 1.0 Content-Transfer-Encoding: 8bit Precedence: bulk List-ID: X-Mailing-List: linux-kernel@vger.kernel.org When truncating pagecache on file THP, the private pages of a process should not be unmapped mapping. This incorrect behavior on a dynamic shared libraries which will cause related processes to happen core dump. A simple test for a DSO (Prerequisite is the DSO mapped in file THP): int main(int argc, char *argv[]) { int fd; fd = open(argv[1], O_WRONLY); if (fd < 0) { perror("open"); } close(fd); return 0; } The test only to open a target DSO, and do nothing. But this operation will lead one or more process to happen core dump. This patch mainly to fix this bug. Fixes: eb6ecbed0aa2 ("mm, thp: relax the VM_DENYWRITE constraint on file-backed THPs") Cc: Tested-by: Xu Yu Signed-off-by: Rongwei Wang --- fs/open.c | 11 ++++++++++- 1 file changed, 10 insertions(+), 1 deletion(-) diff --git a/fs/open.c b/fs/open.c index e73bf88e5060..f732fb94600c 100644 --- a/fs/open.c +++ b/fs/open.c @@ -857,8 +857,17 @@ static int do_dentry_open(struct file *f, */ smp_mb(); if (filemap_nr_thps(inode->i_mapping)) { + struct address_space *mapping = inode->i_mapping; + filemap_invalidate_lock(inode->i_mapping); - truncate_pagecache(inode, 0); + /* + * unmap_mapping_range just need to be called once + * here, because the private pages is not need to be + * unmapped mapping (e.g. data segment of dynamic + * shared libraries here). + */ + unmap_mapping_range(mapping, 0, 0, 0); + truncate_inode_pages(mapping, 0); filemap_invalidate_unlock(inode->i_mapping); } } -- 2.27.0