From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753568Ab3A3PNZ (ORCPT ); Wed, 30 Jan 2013 10:13:25 -0500 Received: from mx1.redhat.com ([209.132.183.28]:16067 "EHLO mx1.redhat.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751153Ab3A3PNW (ORCPT ); Wed, 30 Jan 2013 10:13:22 -0500 Message-ID: <51093864.9000008@redhat.com> Date: Wed, 30 Jan 2013 16:12:36 +0100 From: Jerome Marchand User-Agent: Mozilla/5.0 (X11; Linux i686; rv:15.0) Gecko/20120911 Thunderbird/15.0.1 MIME-Version: 1.0 To: Minchan Kim CC: Greg Kroah-Hartman , linux-mm@kvack.org, linux-kernel@vger.kernel.org, Nitin Gupta , Seth Jennings , Konrad Rzeszutek Wilk , Dan Magenheimer , Pekka Enberg , stable@vger.kernel.org, Pekka Enberg Subject: Re: [PATCH v6 1/4] zram: Fix deadlock bug in partial read/write References: <1359513702-18709-1-git-send-email-minchan@kernel.org> In-Reply-To: <1359513702-18709-1-git-send-email-minchan@kernel.org> Content-Type: text/plain; charset=ISO-8859-1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On 01/30/2013 03:41 AM, Minchan Kim wrote: > Now zram allocates new page with GFP_KERNEL in zram I/O path > if IO is partial. Unfortunately, It may cause deadlock with > reclaim path like below. > > write_page from fs > fs_lock > allocation(GFP_KERNEL) > reclaim > pageout > write_page from fs > fs_lock <-- deadlock > > This patch fixes it by using GFP_NOIO. In read path, we > reorganize code flow so that kmap_atomic is called after the > GFP_NOIO allocation. For the all series: Acked-by: Jerome Marchand > > Cc: stable@vger.kernel.org > Cc: Jerome Marchand > Acked-by: Nitin Gupta > [ penberg@kernel.org: don't use GFP_ATOMIC ] > Signed-off-by: Pekka Enberg > Signed-off-by: Minchan Kim > --- > drivers/staging/zram/zram_drv.c | 9 +++++---- > 1 file changed, 5 insertions(+), 4 deletions(-) > > diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c > index 77a3f0d..5ff8749 100644 > --- a/drivers/staging/zram/zram_drv.c > +++ b/drivers/staging/zram/zram_drv.c > @@ -217,11 +217,12 @@ static int zram_bvec_read(struct zram *zram, struct bio_vec *bvec, > return 0; > } > > - user_mem = kmap_atomic(page); > if (is_partial_io(bvec)) > /* Use a temporary buffer to decompress the page */ > - uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL); > - else > + uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); > + > + user_mem = kmap_atomic(page); > + if (!is_partial_io(bvec)) > uncmem = user_mem; > > if (!uncmem) { > @@ -268,7 +269,7 @@ static int zram_bvec_write(struct zram *zram, struct bio_vec *bvec, u32 index, > * This is a partial IO. We need to read the full page > * before to write the changes. > */ > - uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL); > + uncmem = kmalloc(PAGE_SIZE, GFP_NOIO); > if (!uncmem) { > pr_info("Error allocating temp memory!\n"); > ret = -ENOMEM; >