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 Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by smtp.lore.kernel.org (Postfix) with ESMTP id 66DBBC433EF for ; Wed, 17 Nov 2021 00:33:18 +0000 (UTC) Received: from kanga.kvack.org (kanga.kvack.org [205.233.56.17]) by mail.kernel.org (Postfix) with ESMTP id 041DA63222 for ; Wed, 17 Nov 2021 00:33:17 +0000 (UTC) DMARC-Filter: OpenDMARC Filter v1.4.1 mail.kernel.org 041DA63222 Authentication-Results: mail.kernel.org; dmarc=none (p=none dis=none) header.from=linux-foundation.org Authentication-Results: mail.kernel.org; spf=pass smtp.mailfrom=kvack.org Received: by kanga.kvack.org (Postfix) id 6CAC06B0071; Tue, 16 Nov 2021 19:33:07 -0500 (EST) Received: by kanga.kvack.org (Postfix, from userid 40) id 679926B0072; Tue, 16 Nov 2021 19:33:07 -0500 (EST) X-Delivered-To: int-list-linux-mm@kvack.org Received: by kanga.kvack.org (Postfix, from userid 63042) id 541376B0073; Tue, 16 Nov 2021 19:33:07 -0500 (EST) X-Delivered-To: linux-mm@kvack.org Received: from forelay.hostedemail.com (smtprelay0004.hostedemail.com [216.40.44.4]) by kanga.kvack.org (Postfix) with ESMTP id 456C36B0071 for ; Tue, 16 Nov 2021 19:33:07 -0500 (EST) Received: from smtpin30.hostedemail.com (10.5.19.251.rfc1918.com [10.5.19.251]) by forelay01.hostedemail.com (Postfix) with ESMTP id 11E47181E1886 for ; Wed, 17 Nov 2021 00:32:57 +0000 (UTC) X-FDA: 78816547194.30.833933F Received: from mail.kernel.org (mail.kernel.org [198.145.29.99]) by imf04.hostedemail.com (Postfix) with ESMTP id 0712450000A4 for ; Wed, 17 Nov 2021 00:32:55 +0000 (UTC) Received: by mail.kernel.org (Postfix) with ESMTPSA id 0905A61BC1; Wed, 17 Nov 2021 00:32:54 +0000 (UTC) DKIM-Signature: v=1; a=rsa-sha256; c=relaxed/simple; d=linux-foundation.org; s=korg; t=1637109174; bh=4ehezVXpITBCHc4J+gow4tVXnCNkebvtkbiRdkXSy/Y=; h=Date:From:To:Cc:Subject:In-Reply-To:References:From; b=hxrfhUj7qs4e7T6mXSAD3IZWn7BS9hSEvfPE4LPSXT82ansngLJcCW7XcqxPmES2v nWdr8uzhGxk00DVmn9p4kHxYHMwlOQKcXgPmQ1hbA3C6ks/9K2UHmCLcTc4sip/Epk RF2/wwxo38PPe3CUKb5Sr/CiuEj6S8UtKEnX5ux0= Date: Tue, 16 Nov 2021 16:32:52 -0800 From: Andrew Morton To: Mina Almasry Cc: Mike Kravetz , Wei Xu , James Houghton , linux-mm@kvack.org, linux-kernel@vger.kernel.org Subject: Re: [PATCH v1] hugetlb, userfaultfd: Fix reservation restore on userfaultfd error Message-Id: <20211116163252.0d4643fc0593b8fcaf7aa4ac@linux-foundation.org> In-Reply-To: <20211116235733.3774702-1-almasrymina@google.com> References: <20211116235733.3774702-1-almasrymina@google.com> X-Mailer: Sylpheed 3.5.1 (GTK+ 2.24.31; x86_64-pc-linux-gnu) Mime-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit X-Rspamd-Server: rspam06 X-Rspamd-Queue-Id: 0712450000A4 X-Stat-Signature: jf1hu57frn1izrbtshpti1zxf11hdyfs Authentication-Results: imf04.hostedemail.com; dkim=pass header.d=linux-foundation.org header.s=korg header.b=hxrfhUj7; spf=pass (imf04.hostedemail.com: domain of akpm@linux-foundation.org designates 198.145.29.99 as permitted sender) smtp.mailfrom=akpm@linux-foundation.org; dmarc=none X-HE-Tag: 1637109175-337353 X-Bogosity: Ham, tests=bogofilter, spamicity=0.000000, version=1.2.4 Sender: owner-linux-mm@kvack.org Precedence: bulk X-Loop: owner-majordomo@kvack.org List-ID: On Tue, 16 Nov 2021 15:57:32 -0800 Mina Almasry wrote: > Currently in the is_continue case in hugetlb_mcopy_atomic_pte(), if we > bail out using "goto out_release_unlock;" in the cases where idx >= > size, or !huge_pte_none(), the code will detect that new_pagecache_page > == false, and so call restore_reserve_on_error(). > In this case I see restore_reserve_on_error() delete the reservation, > and the following call to remove_inode_hugepages() will increment > h->resv_hugepages causing a 100% reproducible leak. > > We should treat the is_continue case similar to adding a page into the > pagecache and set new_pagecache_page to true, to indicate that there is > no reservation to restore on the error path, and we need not call > restore_reserve_on_error(). > > Cc: Wei Xu > > Fixes: c7b1850dfb41 ("hugetlb: don't pass page cache pages to restore_reserve_on_error") I added cc:stable to this.