From: Minchan Kim <minchan@kernel.org>
To: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Cc: linux-mm@kvack.org, linux-kernel@vger.kernel.org,
Nitin Gupta <ngupta@vflare.org>,
Seth Jennings <sjenning@linux.vnet.ibm.com>,
Konrad Rzeszutek Wilk <konrad@darnok.org>,
Dan Magenheimer <dan.magenheimer@oracle.com>,
Pekka Enberg <penberg@cs.helsinki.fi>,
jmarchan@redhat.com, Minchan Kim <minchan@kernel.org>,
stable@vger.kernel.org, Pekka Enberg <penberg@kernel.org>
Subject: [PATCH v6 1/4] zram: Fix deadlock bug in partial read/write
Date: Wed, 30 Jan 2013 11:41:39 +0900 [thread overview]
Message-ID: <1359513702-18709-1-git-send-email-minchan@kernel.org> (raw)
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
Cc: Jerome Marchand <jmarchan@redhat.com>
Acked-by: Nitin Gupta <ngupta@vflare.org>
[ penberg@kernel.org: don't use GFP_ATOMIC ]
Signed-off-by: Pekka Enberg <penberg@kernel.org>
Signed-off-by: Minchan Kim <minchan@kernel.org>
---
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;
--
1.7.9.5
next reply other threads:[~2013-01-30 2:41 UTC|newest]
Thread overview: 9+ messages / expand[flat|nested] mbox.gz Atom feed top
2013-01-30 2:41 Minchan Kim [this message]
2013-01-30 2:41 ` [PATCH v6 2/4] zram: force disksize setting before using zram Minchan Kim
2013-01-30 2:41 ` [PATCH v6 3/4] zram: give up lazy initialization of zram metadata Minchan Kim
2013-01-30 2:41 ` [PATCH v6 4/4] zram: get rid of lockdep warning Minchan Kim
2013-02-04 1:53 ` Greg Kroah-Hartman
2013-02-04 3:42 ` Minchan Kim
2013-02-04 3:50 ` Greg Kroah-Hartman
2013-02-04 3:58 ` Minchan Kim
2013-01-30 15:12 ` [PATCH v6 1/4] zram: Fix deadlock bug in partial read/write Jerome Marchand
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