Re: [PATCH] mm: introduce kv[mz]alloc helpers

[Tetsuo Handa <penguin-kernel@I-love.SAKURA.ne.jp>]

On 2017/01/04 23:20, Michal Hocko wrote:
> OK, so I've checked the open coded implementations and converted most of
> them. There are few which are either confused and need some special
> handling or need double checking.
> 
> diff --git a/drivers/md/bcache/util.h b/drivers/md/bcache/util.h
> index cf2cbc211d83..9dc0f0ff0321 100644
> --- a/drivers/md/bcache/util.h
> +++ b/drivers/md/bcache/util.h
> @@ -44,10 +44,7 @@ struct closure;
>  	(heap)->size = (_size);						\
>  	_bytes = (heap)->size * sizeof(*(heap)->data);			\
>  	(heap)->data = NULL;						\
> -	if (_bytes < KMALLOC_MAX_SIZE)					\
> -		(heap)->data = kmalloc(_bytes, (gfp));			\
> -	if ((!(heap)->data) && ((gfp) & GFP_KERNEL))			\
> -		(heap)->data = vmalloc(_bytes);				\
> +	(heap)->data = kvmalloc(_bytes, (gfp) & GFP_KERNEL);		\
>  	(heap)->data;							\
>  })
>  
> @@ -138,10 +135,7 @@ do {									\
>  	(fifo)->front = (fifo)->back = 0;				\
>  	(fifo)->data = NULL;						\
>  									\
> -	if (_bytes < KMALLOC_MAX_SIZE)					\
> -		(fifo)->data = kmalloc(_bytes, (gfp));			\
> -	if ((!(fifo)->data) && ((gfp) & GFP_KERNEL))			\
> -		(fifo)->data = vmalloc(_bytes);				\
> +	(fifo)->data = kvmalloc(_bytes, (gfp) & GFP_KERNEL);		\
>  	(fifo)->data;							\
>  })

These macros are doing strange checks.
((gfp) & GFP_KERNEL) means any bit in GFP_KERNEL is set.
((gfp) & GFP_KERNEL) == GFP_KERNEL might make sense. Actually,
all callers seems to be passing GFP_KERNEL to these macros.

Kent, how do you want to correct this? You want to apply
a patch that removes gfp argument before applying this patch?
Or, you want Michal to directly overwrite by this patch?

Michal, "(fifo)->data = NULL;" line will become redundant
and "(gfp) & GFP_KERNEL" will become "GFP_KERNEL".

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