diff options
| author | Minchan Kim <minchan@kernel.org> | 2013-01-30 11:41:39 +0900 |
|---|---|---|
| committer | Greg Kroah-Hartman <gregkh@linuxfoundation.org> | 2013-02-03 17:52:49 -0800 |
| commit | 7e5a5104c6af709a8d97d5f4711e7c917761d464 (patch) | |
| tree | 0813b4b28b95db4547daaa60757c144cc4a1a77f /drivers/staging/zram | |
| parent | 7f70410fe03f9f31a99bb5074b5e3c48f3b90541 (diff) | |
| download | lwn-7e5a5104c6af709a8d97d5f4711e7c917761d464.tar.gz lwn-7e5a5104c6af709a8d97d5f4711e7c917761d464.zip | |
zram: Fix deadlock bug in partial read/write
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 <jmarchand@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>
Signed-off-by: Greg Kroah-Hartman <gregkh@linuxfoundation.org>
Diffstat (limited to 'drivers/staging/zram')
| -rw-r--r-- | drivers/staging/zram/zram_drv.c | 9 |
1 files changed, 5 insertions, 4 deletions
diff --git a/drivers/staging/zram/zram_drv.c b/drivers/staging/zram/zram_drv.c index 941b7c62ea20..262265e4fa2e 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; |