linux-kernel - Re: [PATCH v4 1/3] mm/gup: add make_dirty arg to put_user_pages_dirty

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Message-ID: <20190801060755.GA14893@lst.de>
Date:   Thu, 1 Aug 2019 08:07:55 +0200
From:   Christoph Hellwig <hch@....de>
To:     john.hubbard@...il.com
Cc:     Andrew Morton <akpm@...ux-foundation.org>,
        Al Viro <viro@...iv.linux.org.uk>,
        Christian Benvenuti <benve@...co.com>,
        Christoph Hellwig <hch@...radead.org>,
        Dan Williams <dan.j.williams@...el.com>,
        "Darrick J . Wong" <darrick.wong@...cle.com>,
        Dave Chinner <david@...morbit.com>,
        Ira Weiny <ira.weiny@...el.com>, Jan Kara <jack@...e.cz>,
        Jason Gunthorpe <jgg@...pe.ca>, Jens Axboe <axboe@...nel.dk>,
        Jerome Glisse <jglisse@...hat.com>,
        "Kirill A . Shutemov" <kirill@...temov.name>,
        Matthew Wilcox <willy@...radead.org>,
        Michal Hocko <mhocko@...nel.org>,
        Mike Marciniszyn <mike.marciniszyn@...el.com>,
        Mike Rapoport <rppt@...ux.ibm.com>,
        linux-block@...r.kernel.org, linux-fsdevel@...r.kernel.org,
        linux-mm@...ck.org, linux-xfs@...r.kernel.org,
        LKML <linux-kernel@...r.kernel.org>,
        John Hubbard <jhubbard@...dia.com>,
        Christoph Hellwig <hch@....de>
Subject: Re: [PATCH v4 1/3] mm/gup: add make_dirty arg to
 put_user_pages_dirty_lock()

On Tue, Jul 30, 2019 at 01:57:03PM -0700, john.hubbard@...il.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.