Re: [PATCH] mm/page_alloc: Add a reason for reserved pages in has_unmovable_pages()

[Anshuman Khandual]

On 10/03/2019 03:02 PM, Anshuman Khandual wrote:
> 
> On 10/03/2019 02:35 PM, Qian Cai wrote:
>>
>>> On Oct 3, 2019, at 4:10 AM, Anshuman Khandual <Anshuman.Khandual@xxxxxxx> wrote:
>>>
>>> Having unmovable pages on a given pageblock should be reported correctly
>>> when required with REPORT_FAILURE flag. But there can be a scenario where a
>>> reserved page in the page block will get reported as a generic "unmovable"
>>> reason code. Instead this should be changed to a more appropriate reason
>>> code like "Reserved page".
>> Isnât this redundant as it dumps the flags in dump_page() anyway?
> Even though page flags does contain reserved bit information, the problem
> is that we are explicitly printing the reason for this page dump. In this
> case it is caused by the fact that it is a reserved page.
> 
> page dumped because: <reason>
> 
> The proposed change makes it explicit that the dump is caused because a
> non movable page with reserved bit set. It also helps in differentiating 
> between reserved bit condition and the last one "if (found > count)"

Instead, will it better to rename the reason codes as

1. "Unmovable (CMA)"
2. "Unmovable (Reserved)"
3. "Unmovable (Private/non-LRU)"