Re: [PATCH 2/3] pipe: enable handling of IOCB_NOWAIT

[Matthew Wilcox <willy@xxxxxxxxxxxxx>]

On Tue, Mar 07, 2023 at 08:10:32PM -0700, Jens Axboe wrote:
> @@ -493,9 +507,13 @@ pipe_write(struct kiocb *iocb, struct iov_iter *from)
>  			int copied;
>  
>  			if (!page) {
> -				page = alloc_page(GFP_HIGHUSER | __GFP_ACCOUNT);
> +				gfp_t gfp = __GFP_HIGHMEM | __GFP_ACCOUNT;
> +
> +				if (!nonblock)
> +					gfp |= GFP_USER;
> +				page = alloc_page(gfp);

Hmm, looks like you drop __GFP_HARDWALL in the nonblock case.  People who
use cpusets might be annoyed by that.

>  				if (unlikely(!page)) {
> -					ret = ret ? : -ENOMEM;
> +					ret = ret ? : nonblock ? -EAGAIN : -ENOMEM;

double ternary operator?  really?

					if (!ret)
						ret = nonblock ? -EAGAIN : -ENOMEM;