Re: [PATCH v4 1/4] zram: Fix deadlock bug in partial write

[Nitin Gupta <ngupta@vflare.org>]

On 01/21/2013 04:07 PM, Minchan Kim wrote:
> Now zram allocates new page with GFP_KERNEL in zram I/O path
> if IO is partial. Unfortunately, It may cuase deadlock with
> reclaim path so this patch solves the problem.
>
> Cc: Nitin Gupta <ngupta@vflare.org>
> Cc: Jerome Marchand <jmarchan@redhat.com>
> Cc: stable@vger.kernel.org
> Signed-off-by: Minchan Kim <minchan@kernel.org>
> ---
>

For the entire series:
Acked-by: Nitin Gupta <ngupta@vflare.org>


> We could use GFP_IO instead of GFP_ATOMIC in zram_bvec_read with
> some modification related to buffer allocation in case of partial IO.
> But it needs more churn and prevent merge this patch into stable
> if we should send this to stable so I'd like to keep it as simple
> as possbile. GFP_IO usage could be separate patch after we merge it.
> Thanks.
>
>   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;
>

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