Re: [PATCH v26 2/5] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

[Muhammad Usama Anjum <usama.anjum@collabora.com>]

On 7/27/23 4:46 PM, Michał Mirosław wrote:
> On Thu, 27 Jul 2023 at 11:37, Muhammad Usama Anjum
> <usama.anjum@collabora.com> wrote:
> [...]
>> --- a/include/uapi/linux/fs.h
>> +++ b/include/uapi/linux/fs.h
> [...]
>> +/*
>> + * struct pm_scan_arg - Pagemap ioctl argument
>> + * @size:              Size of the structure
>> + * @flags:             Flags for the IOCTL
>> + * @start:             Starting address of the region
>> + * @end:               Ending address of the region
>> + * @walk_end:          Ending address of the visited memory is returned
>> + *                     (This helps if entire range hasn't been visited)
> 
> "Address where the scan stopped (written by kernel). walk_end == end
> informs that the scan completed."
I'll update comment.

> 
> (To make the userspace life easier, we can copy `end` (only) in case
> of full scan completion, so that the tag is retained.)
Lets be consist and not copy tag from end to walk_end as we'll now know
about tag every time. It should be the responsibility of the user to deal
with it.

> 
>> + * @vec:               Address of page_region struct array for output
>> + * @vec_len:           Length of the page_region struct array
>> + * @max_pages:         Optional limit for number of returned pages (0 = disabled)
>> + * @category_inverted: PAGE_IS_* categories which values match if 0 instead of 1
>> + * @category_mask:     Skip pages for which any category doesn't match
>> + * @category_anyof_mask: Skip pages for which no category matches
>> + * @return_mask:       PAGE_IS_* categories that are to be reported in `page_region`s returned
>> + */

-- 
BR,
Muhammad Usama Anjum