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

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

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

-- 
BR,
Muhammad Usama Anjum