linux-kernel - Re: [PATCH 2/3] pagewalk: separate function pointers from iterator data

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Message-ID: <20190828150514.GN914@mellanox.com>
Date:   Wed, 28 Aug 2019 15:05:19 +0000
From:   Jason Gunthorpe <jgg@...lanox.com>
To:     Christoph Hellwig <hch@....de>
CC:     Linus Torvalds <torvalds@...ux-foundation.org>,
        Andrew Morton <akpm@...ux-foundation.org>,
        Thomas Hellström <thomas@...pmail.org>,
        Jerome Glisse <jglisse@...hat.com>,
        Steven Price <steven.price@....com>,
        "linux-mm@...ck.org" <linux-mm@...ck.org>,
        "linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
        Thomas Hellstrom <thellstrom@...are.com>
Subject: Re: [PATCH 2/3] pagewalk: separate function pointers from iterator
 data

On Wed, Aug 28, 2019 at 04:19:54PM +0200, Christoph Hellwig wrote:
> @@ -2546,7 +2542,7 @@ int s390_enable_sie(void)
>  	mm->context.has_pgste = 1;
>  	/* split thp mappings and disable thp for future mappings */
>  	thp_split_mm(mm);
> -	zap_zero_pages(mm);
> +	walk_page_range(mm, 0, TASK_SIZE, &zap_zero_walk_ops, NULL);
>  	up_write(&mm->mmap_sem);
>  	return 0;
>  }

[..]

> @@ -1217,7 +1222,8 @@ static ssize_t clear_refs_write(struct file *file, const char __user *buf,
>  						0, NULL, mm, 0, -1UL);
>  			mmu_notifier_invalidate_range_start(&range);
>  		}
> -		walk_page_range(0, mm->highest_vm_end, &clear_refs_walk);
> +		walk_page_range(mm, 0, mm->highest_vm_end, &clear_refs_walk_ops,
> +				&cp);

Is the difference between TASK_SIZE and 'highest_vm_end' deliberate,
or should we add a 'walk_all_pages'() mini helper for this? I see most
of the users are using one or the other variant.

Otherwise the mechanical transformation looked OK to me

Reviewed-by: Jason Gunthorpe <jgg@...lanox.com>

Jason