From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754071Ab3BCXqS (ORCPT ); Sun, 3 Feb 2013 18:46:18 -0500 Received: from LGEMRELSE1Q.lge.com ([156.147.1.111]:54201 "EHLO LGEMRELSE1Q.lge.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1753952Ab3BCXqP (ORCPT ); Sun, 3 Feb 2013 18:46:15 -0500 X-AuditID: 9c93016f-b7b70ae000000e36-fa-510ef6c56ab7 From: Minchan Kim To: Greg Kroah-Hartman Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org, Nitin Gupta , Seth Jennings , Konrad Rzeszutek Wilk , Dan Magenheimer , Pekka Enberg , jmarchan@redhat.com, Andrew Morton , Minchan Kim , stable@vger.kernel.org, Pekka Enberg Subject: [PATCH v7 1/4] zram: Fix deadlock bug in partial read/write Date: Mon, 4 Feb 2013 08:46:08 +0900 Message-Id: <1359935171-12749-1-git-send-email-minchan@kernel.org> X-Mailer: git-send-email 1.7.9.5 X-Brightmail-Tracker: AAAAAA== Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org 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. Cc: stable@vger.kernel.org Acked-by: 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 941b7c6..262265e 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; -- 1.7.9.5