From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: X-Cyrus-Session-Id: sloti22d1t05-2885895-1521202387-2-7178548064577087783 X-Sieve: CMU Sieve 3.0 X-Spam-known-sender: no X-Spam-score: 0.0 X-Spam-hits: BAYES_00 -1.9, ME_NOAUTH 0.01, RCVD_IN_DNSWL_HI -5, T_RP_MATCHES_RCVD -0.01, LANGUAGES en, BAYES_USED global, SA_VERSION 3.4.0 X-Spam-source: IP='209.132.180.67', Host='vger.kernel.org', Country='CN', FromHeader='org', MailFrom='org' X-Spam-charsets: plain='us-ascii' X-Resolved-to: greg@kroah.com X-Delivered-to: greg@kroah.com X-Mail-from: stable-owner@vger.kernel.org ARC-Seal: i=1; a=rsa-sha256; cv=none; d=messagingengine.com; s=arctest; t=1521202386; b=u8HeJ2xckPclz6AqOj13r1cExKf3eb3wwyQOxc2ZG2nCyXb srbrSvSh5DxxhcpN1ldsfhvfmW1oVFH2/y3bp/kGgu9jLRXYwmWk23rwiqHG1UW2 XEvZZWSs1V/fNZGh2e1IY/ZXTez/W3KrB071ow6mmFakt0YKw3+4XejMc5ObQj27 ARqSBtOPHlFXgqFIFdzVR6++lahXA1MjOgM6qYDZmzhc2WXAtgOnI6eoFFQdKRwm 5JV1Am2jYXwgDtQ2bVEP16+UebsRiry0X/yNFLuO1CTEqEnfPijTe8+p/HW8S87x 3zCA6g6T8dBYd5twx/4XtHH2SbkvU8sOtbahfZA== ARC-Message-Signature: i=1; a=rsa-sha256; c=relaxed/relaxed; d= messagingengine.com; h=date:from:to:cc:subject:message-id :references:mime-version:content-type:in-reply-to:sender :list-id; s=arctest; t=1521202386; bh=QvxLmDbGnNXayajr1z4CqLzVJZ W9rOHhuXIDpcXTYoI=; b=mOJinBxEtROAGjVMZmyo2oWuDkid315alJvPEadijC 62Rx7IyOa2goh7b+m1rFi0lv0cDf4BR0wv0RbCtbRZuQgtjK1W7OiX1Bmq3spmbv 2J2WvrPTd0c/FhinLIX1Rna4ZysZd0ylfbKAz4wtrDX7z+tsKPLqtEbuZ3NMvQYq ouA30zTTA1mSJhwZ8h4NCAfuchQaA/l+Eq98IndYLWQTDeskNEw8iqxGXqUOpfg7 XLsHIBap7vdX2iEwxo2dfjjaut+xOTiHyuS9wtKwQUsaOzX5MBI3k/qJbw3AIy/u qkJF/pkA+DaEgmOomO2izEqUWYfb1GfRJMGKUf9DMpBg== ARC-Authentication-Results: i=1; mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes Authentication-Results: mx5.messagingengine.com; arc=none (no signatures found); dkim=none (no signatures found); dmarc=none (p=none,has-list-id=yes,d=none) header.from=kernel.org; iprev=pass policy.iprev=209.132.180.67 (vger.kernel.org); spf=none smtp.mailfrom=stable-owner@vger.kernel.org smtp.helo=vger.kernel.org; x-aligned-from=orgdomain_pass; x-category=clean score=-100 state=0; x-ptr=pass x-ptr-helo=vger.kernel.org x-ptr-lookup=vger.kernel.org; x-return-mx=pass smtp.domain=vger.kernel.org smtp.result=pass smtp_org.domain=kernel.org smtp_org.result=pass smtp_is_org_domain=no header.domain=kernel.org header.result=pass header_is_org_domain=yes Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1751480AbeCPMNF (ORCPT ); Fri, 16 Mar 2018 08:13:05 -0400 Received: from mx2.suse.de ([195.135.220.15]:43206 "EHLO mx2.suse.de" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751437AbeCPMNF (ORCPT ); Fri, 16 Mar 2018 08:13:05 -0400 Date: Fri, 16 Mar 2018 13:13:03 +0100 From: Michal Hocko To: "Kirill A. Shutemov" Cc: Andrew Morton , linux-mm@kvack.org, linux-kernel@vger.kernel.org, stable@vger.kernel.org Subject: Re: [PATCH] mm/shmem: Do not wait for lock_page() in shmem_unused_huge_shrink() Message-ID: <20180316121303.GI23100@dhcp22.suse.cz> References: <20180316105908.62516-1-kirill.shutemov@linux.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20180316105908.62516-1-kirill.shutemov@linux.intel.com> User-Agent: Mutt/1.9.4 (2018-02-28) Sender: stable-owner@vger.kernel.org X-Mailing-List: stable@vger.kernel.org X-getmail-retrieved-from-mailbox: INBOX X-Mailing-List: linux-kernel@vger.kernel.org List-ID: On Fri 16-03-18 13:59:08, Kirill A. Shutemov wrote: [..] > @@ -498,31 +498,42 @@ static unsigned long shmem_unused_huge_shrink(struct shmem_sb_info *sbinfo, > continue; > } > > - page = find_lock_page(inode->i_mapping, > + page = find_get_page(inode->i_mapping, > (inode->i_size & HPAGE_PMD_MASK) >> PAGE_SHIFT); > if (!page) > goto drop; > > + /* No huge page at the end of the file: nothing to split */ > if (!PageTransHuge(page)) { > - unlock_page(page); > put_page(page); > goto drop; > } > > + /* > + * Leave the inode on the list if we failed to lock > + * the page at this time. > + * > + * Waiting for the lock may lead to deadlock in the > + * reclaim path. > + */ > + if (!trylock_page(page)) { > + put_page(page); > + goto leave; > + } Can somebody split the huge page after the PageTransHuge check and before we lock it? > + > ret = split_huge_page(page); > unlock_page(page); > put_page(page); > > - if (ret) { > - /* split failed: leave it on the list */ > - iput(inode); > - continue; > - } > + /* If split failed leave the inode on the list */ > + if (ret) > + goto leave; > > split++; > drop: > list_del_init(&info->shrinklist); > removed++; > +leave: > iput(inode); > } > > -- > 2.16.1 -- Michal Hocko SUSE Labs