On 01/28/2013 08:16 AM, Pekka Enberg wrote:
> On Mon, Jan 28, 2013 at 2:38 AM, Minchan Kim <minc...@kernel.org> wrote:
>> Now zram allocates new page with GFP_KERNEL in zram I/O path
>> if IO is partial. Unfortunately, It may cuase deadlock with
>
> s/cuase/cause/g
>
>> reclaim path so this patch solves the problem.
>
> It'd be nice to know about the problem in more detail. I'm also
> curious on why you decided on GFP_ATOMIC for the read path and
> GFP_NOIO in the write path.
This is because we're holding a kmap_atomic page in the read path.
Jerome
>
>>
>> Cc: sta...@vger.kernel.org
>> Cc: Jerome Marchand <jmarc...@redhat.com>
>> Acked-by: Nitin Gupta <ngu...@vflare.org>
>> Signed-off-by: Minchan Kim <minc...@kernel.org>
>> ---
>> drivers/staging/zram/zram_drv.c | 4 ++--
>> 1 file changed, 2 insertions(+), 2 deletions(-)
>>
>> diff --git a/drivers/staging/zram/zram_drv.c
>> b/drivers/staging/zram/zram_drv.c
>> index 61fb8f1..b285b3a 100644
>> --- a/drivers/staging/zram/zram_drv.c
>> +++ b/drivers/staging/zram/zram_drv.c
>> @@ -220,7 +220,7 @@ static int zram_bvec_read(struct zram *zram, struct
>> bio_vec *bvec,
>> user_mem = kmap_atomic(page);
>> if (is_partial_io(bvec))
>> /* Use a temporary buffer to decompress the page */
>> - uncmem = kmalloc(PAGE_SIZE, GFP_KERNEL);
>> + uncmem = kmalloc(PAGE_SIZE, GFP_ATOMIC);
>> else
>> uncmem = user_mem;
>>
>> @@ -268,7 +268,7 @@ 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
>>
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