This is a note to let you know that I've just added the patch titled
zram: Fix deadlock bug in partial read/write
to the 3.4-stable tree which can be found at:
http://www.kernel.org/git/?p=linux/kernel/git/stable/stable-queue.git;a=summary
The filename of the patch is:
zram-fix-deadlock-bug-in-partial-read-write.patch
and it can be found in the queue-3.4 subdirectory.
If you, or anyone else, feels it should not be added to the stable tree,
please let <stable@xxxxxxxxxxxxxxx> know about it.
>From 41247561dc218af7ab5cb4113b0c8ee1f79b75de Mon Sep 17 00:00:00 2001
From: Minchan Kim <minchan@xxxxxxxxxx>
Date: Wed, 30 Jan 2013 11:41:39 +0900
Subject: zram: Fix deadlock bug in partial read/write
From: Minchan Kim <minchan@xxxxxxxxxx>
commit 7e5a5104c6af709a8d97d5f4711e7c917761d464 upstream.
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.
Acked-by: Jerome Marchand <jmarchand@xxxxxxxxxx>
Acked-by: Nitin Gupta <ngupta@xxxxxxxxxx>
[ penberg@xxxxxxxxxx: don't use GFP_ATOMIC ]
Signed-off-by: Pekka Enberg <penberg@xxxxxxxxxx>
Signed-off-by: Minchan Kim <minchan@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
[bwh: Backported to 3.2: no reordering is needed in the read path]
Signed-off-by: Ben Hutchings <ben@xxxxxxxxxxxxxxx>
Cc: Jianguo Wu <wujianguo@xxxxxxxxxx>
Signed-off-by: Greg Kroah-Hartman <gregkh@xxxxxxxxxxxxxxxxxxx>
---
drivers/staging/zram/zram_drv.c | 4 ++--
1 file changed, 2 insertions(+), 2 deletions(-)
--- a/drivers/staging/zram/zram_drv.c
+++ b/drivers/staging/zram/zram_drv.c
@@ -235,7 +235,7 @@ static int zram_bvec_read(struct zram *z
if (is_partial_io(bvec)) {
/* Use a temporary buffer to decompress the page */
- uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
+ uncmem = kmalloc(PAGE_SIZE, GFP_NOIO);
if (!uncmem) {
pr_info("Error allocating temp memory!\n");
return -ENOMEM;
@@ -330,7 +330,7 @@ static int zram_bvec_write(struct zram *
* 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;
Patches currently in stable-queue which might be from minchan@xxxxxxxxxx are
queue-3.4/zram-destroy-all-devices-on-error-recovery-path-in-zram_init.patch
queue-3.4/zram-fix-deadlock-bug-in-partial-read-write.patch
queue-3.4/staging-zram-fix-access-of-null-pointer.patch
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