[Devel] [PATCH rh7] fs/fuse/dev: improve ->splice() with fragmented memory

[Vasily Averin]

Could you please elaborate, why it should help in reported case?
It seems for me kvmalloc will push reclaimer first exactly like kmalloc does right now.

On 2017-11-29 16:59, Andrey Ryabinin wrote:
> fuse_dev_splice_[read,write]() temporary allocates array of pipe_buffer
> structs. Depending on pipe size it could be quite large, thus we stall
> in high order allocation request. Use kvmalloc() instead of kmalloc()
> to fallback in vmalloc() if high order page is not available at the moment.
> 
> https://jira.sw.ru/browse/PSBM-77949
> Signed-off-by: Andrey Ryabinin <aryabinin at virtuozzo.com>
> ---
>  fs/fuse/dev.c | 8 ++++----
>  1 file changed, 4 insertions(+), 4 deletions(-)
> 
> diff --git a/fs/fuse/dev.c b/fs/fuse/dev.c
> index 3427eddcfb17..83c30e51dfca 100644
> --- a/fs/fuse/dev.c
> +++ b/fs/fuse/dev.c
> @@ -1353,7 +1353,7 @@ static ssize_t fuse_dev_splice_read(struct file *in, loff_t *ppos,
>  	if (!fud)
>  		return -EPERM;
>  
> -	bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
> +	bufs = kvmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
>  	if (!bufs)
>  		return -ENOMEM;
>  
> @@ -1410,7 +1410,7 @@ out:
>  	for (; page_nr < cs.nr_segs; page_nr++)
>  		page_cache_release(bufs[page_nr].page);
>  
> -	kfree(bufs);
> +	kvfree(bufs);
>  	return ret;
>  }
>  
> @@ -1991,7 +1991,7 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
>  	if (!fud)
>  		return -EPERM;
>  
> -	bufs = kmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
> +	bufs = kvmalloc(pipe->buffers * sizeof(struct pipe_buffer), GFP_KERNEL);
>  	if (!bufs)
>  		return -ENOMEM;
>  
> @@ -2049,7 +2049,7 @@ static ssize_t fuse_dev_splice_write(struct pipe_inode_info *pipe,
>  		buf->ops->release(pipe, buf);
>  	}
>  out:
> -	kfree(bufs);
> +	kvfree(bufs);
>  	return ret;
>  }
>  
>