linux-kernel - Re: [PATCH] fs/io_uring.c: convert put_page() to put_user

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Date:   Mon, 5 Aug 2019 15:04:42 -0700
From:   Ira Weiny <ira.weiny@...el.com>
To:     john.hubbard@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Christoph Hellwig <hch@...radead.org>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...pe.ca>,
        Jerome Glisse <jglisse@...hat.com>,
        LKML <linux-kernel@...r.kernel.org>, linux-mm@...ck.org,
        linux-fsdevel@...r.kernel.org, John Hubbard <jhubbard@...dia.com>,
        Alexander Viro <viro@...iv.linux.org.uk>,
        Jens Axboe <axboe@...nel.dk>, linux-block@...r.kernel.org
Subject: Re: [PATCH] fs/io_uring.c: convert put_page() to put_user_page*()

On Sun, Aug 04, 2019 at 07:32:06PM -0700, john.hubbard@...il.com wrote:
> From: John Hubbard <jhubbard@...dia.com>
> 
> For pages that were retained via get_user_pages*(), release those pages
> via the new put_user_page*() routines, instead of via put_page() or
> release_pages().
> 
> This is part a tree-wide conversion, as described in commit fc1d8e7cca2d
> ("mm: introduce put_user_page*(), placeholder versions").
> 
> Cc: Alexander Viro <viro@...iv.linux.org.uk>
> Cc: Jens Axboe <axboe@...nel.dk>
> Cc: linux-fsdevel@...r.kernel.org
> Cc: linux-block@...r.kernel.org
> Signed-off-by: John Hubbard <jhubbard@...dia.com>

Signed-off-by: Ira Weiny <ira.weiny@...el.com>

> ---
>  fs/io_uring.c | 8 +++-----
>  1 file changed, 3 insertions(+), 5 deletions(-)
> 
> diff --git a/fs/io_uring.c b/fs/io_uring.c
> index d542f1cf4428..8a1de5ab9c6d 100644
> --- a/fs/io_uring.c
> +++ b/fs/io_uring.c
> @@ -2815,7 +2815,7 @@ static int io_sqe_buffer_unregister(struct io_ring_ctx *ctx)
>  		struct io_mapped_ubuf *imu = &ctx->user_bufs[i];
>  
>  		for (j = 0; j < imu->nr_bvecs; j++)
> -			put_page(imu->bvec[j].bv_page);
> +			put_user_page(imu->bvec[j].bv_page);
>  
>  		if (ctx->account_mem)
>  			io_unaccount_mem(ctx->user, imu->nr_bvecs);
> @@ -2959,10 +2959,8 @@ static int io_sqe_buffer_register(struct io_ring_ctx *ctx, void __user *arg,
>  			 * if we did partial map, or found file backed vmas,
>  			 * release any pages we did get
>  			 */
> -			if (pret > 0) {
> -				for (j = 0; j < pret; j++)
> -					put_page(pages[j]);
> -			}
> +			if (pret > 0)
> +				put_user_pages(pages, pret);
>  			if (ctx->account_mem)
>  				io_unaccount_mem(ctx->user, nr_pages);
>  			kvfree(imu->bvec);
> -- 
> 2.22.0
>