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=-10.7 required=3.0 tests=DKIMWL_WL_HIGH,DKIM_SIGNED, DKIM_VALID,HEADER_FROM_DIFFERENT_DOMAINS,INCLUDES_PATCH,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 E877BC04EBF for ; Tue, 4 Dec 2018 11:11:20 +0000 (UTC) Received: from vger.kernel.org (vger.kernel.org [209.132.180.67]) by mail.kernel.org (Postfix) with ESMTP id AFE272082D for ; Tue, 4 Dec 2018 11:11:20 +0000 (UTC) Authentication-Results: mail.kernel.org; dkim=pass (1024-bit key) header.d=kernel.org header.i=@kernel.org header.b="vzKOi7lo" DMARC-Filter: OpenDMARC Filter v1.3.2 mail.kernel.org AFE272082D Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linuxfoundation.org Authentication-Results: mail.kernel.org; spf=none smtp.mailfrom=linux-kernel-owner@vger.kernel.org Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1728585AbeLDLLT (ORCPT ); Tue, 4 Dec 2018 06:11:19 -0500 Received: from mail.kernel.org ([198.145.29.99]:58610 "EHLO mail.kernel.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1728507AbeLDLI7 (ORCPT ); Tue, 4 Dec 2018 06:08:59 -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 1E029214DB; Tue, 4 Dec 2018 11:08:58 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=kernel.org; s=default; t=1543921738; bh=kSwrj/y6N1gLvfnF3l6UGNZ+cWKblqNB7gBF1VGcL0g=; h=From:To:Cc:Subject:Date:In-Reply-To:References:From; b=vzKOi7loN21ugae9pT1mafJHdtuLx/vrfyh820/Fa/VLgwnpUpZma20//MeRBsRi+ R027LX7Yy3rIOiYroOhHamzn48Q1TuauHa+o/3ZjKnv01Y85q46sKWAckcFo7dicHE MnXjd6BnE4zYBDptVln78Nq6i/9k2TK4Brwqkj8w= From: Greg Kroah-Hartman To: linux-kernel@vger.kernel.org Cc: Greg Kroah-Hartman , stable@vger.kernel.org, Hugh Dickins , Matthew Wilcox , "Kirill A. Shutemov" , Jerome Glisse , Konstantin Khlebnikov , Andrew Morton , Linus Torvalds , Sasha Levin Subject: [PATCH 4.9 05/50] mm/khugepaged: collapse_shmem() stop if punched or truncated Date: Tue, 4 Dec 2018 11:50:00 +0100 Message-Id: <20181204103714.772372883@linuxfoundation.org> X-Mailer: git-send-email 2.19.2 In-Reply-To: <20181204103714.485546262@linuxfoundation.org> References: <20181204103714.485546262@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. ------------------ commit 701270fa193aadf00bdcf607738f64997275d4c7 upstream. Huge tmpfs testing showed that although collapse_shmem() recognizes a concurrently truncated or hole-punched page correctly, its handling of holes was liable to refill an emptied extent. Add check to stop that. Link: http://lkml.kernel.org/r/alpine.LSU.2.11.1811261522040.2275@eggly.anvils Fixes: f3f0e1d2150b2 ("khugepaged: add support of collapse for tmpfs/shmem pages") Signed-off-by: Hugh Dickins Reviewed-by: Matthew Wilcox Cc: Kirill A. Shutemov Cc: Jerome Glisse Cc: Konstantin Khlebnikov Cc: [4.8+] Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds Signed-off-by: Sasha Levin --- mm/khugepaged.c | 15 +++++++++++++++ 1 file changed, 15 insertions(+) diff --git a/mm/khugepaged.c b/mm/khugepaged.c index 1df37ee996d5..62de24194f24 100644 --- a/mm/khugepaged.c +++ b/mm/khugepaged.c @@ -1351,6 +1351,16 @@ static void collapse_shmem(struct mm_struct *mm, radix_tree_for_each_slot(slot, &mapping->page_tree, &iter, start) { int n = min(iter.index, end) - index; + /* + * Stop if extent has been hole-punched, and is now completely + * empty (the more obvious i_size_read() check would take an + * irq-unsafe seqlock on 32-bit). + */ + if (n >= HPAGE_PMD_NR) { + result = SCAN_TRUNCATED; + goto tree_locked; + } + /* * Handle holes in the radix tree: charge it from shmem and * insert relevant subpage of new_page into the radix-tree. @@ -1462,6 +1472,11 @@ static void collapse_shmem(struct mm_struct *mm, if (result == SCAN_SUCCEED && index < end) { int n = end - index; + /* Stop if extent has been truncated, and is now empty */ + if (n >= HPAGE_PMD_NR) { + result = SCAN_TRUNCATED; + goto tree_locked; + } if (!shmem_charge(mapping->host, n)) { result = SCAN_FAIL; goto tree_locked; -- 2.17.1