From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: from mail-wr0-f200.google.com (mail-wr0-f200.google.com [209.85.128.200]) by kanga.kvack.org (Postfix) with ESMTP id 7A7826B0033 for ; Mon, 27 Nov 2017 11:59:15 -0500 (EST) Received: by mail-wr0-f200.google.com with SMTP id r2so14187722wra.4 for ; Mon, 27 Nov 2017 08:59:15 -0800 (PST) Received: from gum.cmpxchg.org (gum.cmpxchg.org. [85.214.110.215]) by mx.google.com with ESMTPS id k21si951994ede.3.2017.11.27.08.59.13 for (version=TLS1_2 cipher=ECDHE-RSA-CHACHA20-POLY1305 bits=256/256); Mon, 27 Nov 2017 08:59:13 -0800 (PST) Date: Mon, 27 Nov 2017 16:59:06 +0000 From: Johannes Weiner Subject: Re: [PATCH v2] mm/cma: fix alloc_contig_range ret code/potential leak Message-ID: <20171127165906.GA16092@cmpxchg.org> References: <15cf0f39-43f9-8287-fcfe-f2502af59e8a@oracle.com> <20171122185214.25285-1-mike.kravetz@oracle.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20171122185214.25285-1-mike.kravetz@oracle.com> Sender: owner-linux-mm@kvack.org List-ID: To: Mike Kravetz Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Joonsoo Kim , Vlastimil Babka , Michal Nazarewicz , Michal Hocko , Mel Gorman , Andrew Morton , stable@vger.kernel.org On Wed, Nov 22, 2017 at 10:52:14AM -0800, Mike Kravetz wrote: > If the call __alloc_contig_migrate_range() in alloc_contig_range > returns -EBUSY, processing continues so that test_pages_isolated() > is called where there is a tracepoint to identify the busy pages. > However, it is possible for busy pages to become available between > the calls to these two routines. In this case, the range of pages > may be allocated. Unfortunately, the original return code (ret > == -EBUSY) is still set and returned to the caller. Therefore, > the caller believes the pages were not allocated and they are leaked. > > Update comment to indicate that allocation is still possible even if > __alloc_contig_migrate_range returns -EBUSY. Also, clear return code > in this case so that it is not accidentally used or returned to caller. > > Fixes: 8ef5849fa8a2 ("mm/cma: always check which page caused allocation failure") > Cc: > Signed-off-by: Mike Kravetz Acked-by: Johannes Weiner -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@kvack.org. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: email@kvack.org