Re: [PATCH v4 1/3] mm/gup: add make_dirty arg to put_user_pages_dirty_lock()

From: Christoph Hellwig <hch@lst.de>
To: john.hubbard@gmail.com
Cc: Andrew Morton <akpm@linux-foundation.org>,
	Al Viro <viro@zeniv.linux.org.uk>,
	Christian Benvenuti <benve@cisco.com>,
	Christoph Hellwig <hch@infradead.org>,
	Dan Williams <dan.j.williams@intel.com>,
	"Darrick J . Wong" <darrick.wong@oracle.com>,
	Dave Chinner <david@fromorbit.com>,
	Ira Weiny <ira.weiny@intel.com>, Jan Kara <jack@suse.cz>,
	Jason Gunthorpe <jgg@ziepe.ca>, Jens Axboe <axboe@kernel.dk>,
	Jerome Glisse <jglisse@redhat.com>,
	"Kirill A . Shutemov" <kirill@shutemov.name>,
	Matthew Wilcox <willy@infradead.org>,
	Michal Hocko <mhocko@kernel.org>,
	Mike Marciniszyn <mike.marciniszyn@intel.com>,
	Mike Rapoport <rppt@linux.ibm.com>,
	linux-block@vger.kernel.org, linux-fsdevel@vger.kernel.org,
	linux-mm@kvack.org, linux-xfs@vger.kernel.org,
	LKML <linux-kernel@vger.kernel.org>,
	John Hubbard <jhubbard@nvidia.com>,
	Christoph Hellwig <hch@lst.de>
Subject: Re: [PATCH v4 1/3] mm/gup: add make_dirty arg to put_user_pages_dirty_lock()
Date: Thu, 1 Aug 2019 08:07:55 +0200	[thread overview]
Message-ID: <20190801060755.GA14893@lst.de> (raw)
In-Reply-To: <20190730205705.9018-2-jhubbard@nvidia.com>

On Tue, Jul 30, 2019 at 01:57:03PM -0700, john.hubbard@gmail.com wrote:
> @@ -40,10 +40,7 @@
>  static void __qib_release_user_pages(struct page **p, size_t num_pages,
>  				     int dirty)
>  {
> -	if (dirty)
> -		put_user_pages_dirty_lock(p, num_pages);
> -	else
> -		put_user_pages(p, num_pages);
> +	put_user_pages_dirty_lock(p, num_pages, dirty);
>  }

__qib_release_user_pages should be removed now as a direct call to
put_user_pages_dirty_lock is a lot more clear.

> index 0b0237d41613..62e6ffa9ad78 100644
> --- a/drivers/infiniband/hw/usnic/usnic_uiom.c
> +++ b/drivers/infiniband/hw/usnic/usnic_uiom.c
> @@ -75,10 +75,7 @@ static void usnic_uiom_put_pages(struct list_head *chunk_list, int dirty)
>  		for_each_sg(chunk->page_list, sg, chunk->nents, i) {
>  			page = sg_page(sg);
>  			pa = sg_phys(sg);
> -			if (dirty)
> -				put_user_pages_dirty_lock(&page, 1);
> -			else
> -				put_user_page(page);
> +			put_user_pages_dirty_lock(&page, 1, dirty);
>  			usnic_dbg("pa: %pa\n", &pa);

There is a pre-existing bug here, as this needs to use the sg_page
iterator.  Probably worth throwing in a fix into your series while you
are at it.

> @@ -63,15 +63,7 @@ struct siw_mem *siw_mem_id2obj(struct siw_device *sdev, int stag_index)
>  static void siw_free_plist(struct siw_page_chunk *chunk, int num_pages,
>  			   bool dirty)
>  {
> -	struct page **p = chunk->plist;
> -
> -	while (num_pages--) {
> -		if (!PageDirty(*p) && dirty)
> -			put_user_pages_dirty_lock(p, 1);
> -		else
> -			put_user_page(*p);
> -		p++;
> -	}
> +	put_user_pages_dirty_lock(chunk->plist, num_pages, dirty);

siw_free_plist should just go away now.

Otherwise this looks good to me.