Re: [PATCH 4/7] mm: Introduce verify_page_range()

[Peter Zijlstra <peterz@infradead.org>]

On Mon, Apr 12, 2021 at 10:28:05AM +0200, Christoph Hellwig wrote:
> On Mon, Apr 12, 2021 at 10:00:16AM +0200, Peter Zijlstra wrote:
> > +extern int verify_page_range(struct mm_struct *mm,
> 
> No need for the extern here.

It's consistent with the rest of the functions there. Also, I personally
like that extern.

> > +int verify_page_range(struct mm_struct *mm,
> > +		      unsigned long addr, unsigned long size,
> > +		      int (*fn)(pte_t pte, unsigned long addr, void *data),
> > +		      void *data)
> 
> A kerneldoc comment would be nice for this function.
> 
> Otherwise this looks fine.

Something like so?

/**
 * verify_page_range() - Scan (and fill) a range of virtual memory and validate PTEs
 * @mm: mm identifying the virtual memory map
 * @addr: starting virtual address of the range
 * @size: size of the range
 * @fn: function that verifies the PTEs
 * @data: opaque data passed to @fn
 *
 * Scan a region of virtual memory, filling in page tables as necessary and
 * calling a provided function on each leaf, providing a copy of the
 * page-table-entry.
 *
 * Similar apply_to_page_range(), but does not provide direct access to the
 * page-tables.
 *
 * NOTE! this function does not work correctly vs large pages.
 *
 * Return: the first !0 return of the provided function, or 0 on completion.
 */
int verify_page_range(struct mm_struct *mm,
		      unsigned long addr, unsigned long size,
		      int (*fn)(pte_t pte, unsigned long addr, void *data),
		      void *data)