Re: [PATCH v31 2/6] fs/proc/task_mmu: Implement IOCTL to get and optionally clear info about PTEs

On 8/16/23 4:17 PM, Michał Mirosław wrote:

On Wed, Aug 16, 2023 at 03:38:10PM +0500, Muhammad Usama Anjum wrote:

...

The PAGEMAP_SCAN IOCTL on the pagemap file can be used to get or optionally clear the info about page table entries.

[...]

...

--- a/fs/proc/task_mmu.c +++ b/fs/proc/task_mmu.c

[...]

...

+static long do_pagemap_scan(struct mm_struct *mm, unsigned long uarg) +{

[...]

...

• for (walk_start = p.arg.start; walk_start < p.arg.end;

• 	walk_start = p.arg.walk_end) {
  

[...]

...

• /* The walk_end isn't set when ret is zero  */
  

• if (!p.arg.walk_end)
  

• 	p.arg.walk_end = p.arg.end;
  

This is now redundant with the `if` after the loop. [1]

...

• if (ret != -ENOSPC)
  

• 	break;
  

• if (p.arg.vec_len == 0 || p.found_pages == p.arg.max_pages)
  

• 	break;
  

• }
• /* ENOSPC signifies early stop (buffer full) from the walk. */
• if (!ret || ret == -ENOSPC)

• ret = n_ranges_out;
  

• if (!p.arg.walk_end)

• p.arg.walk_end = p.arg.end;
  

[1] The one above.

Thank you for noting it down. Let me remove it.

Best Regards Michał Mirosław