Re: [PATCH 1/3] mm/vmscan: restore zone_reclaim_mode ABI

[Dave Hansen]

On 7/2/20 4:28 AM, Huang, Ying wrote:
>> But, when the bit was removed (bit 0) the _other_ bit locations also
>> got changed.  That's not OK because the bit values are documented to
>> mean one specific thing and users surely rely on them meaning that one
>> thing and not changing from kernel to kernel.  The end result is that
>> if someone had a script that did:
>>
>> 	sysctl vm.zone_reclaim_mode=1
>>
>> That script went from doing nothing
> Per my understanding, this script would have enabled node reclaim for
> clean unmapped pages before commit 648b5cf368e0 ("mm/vmscan: remove
> unused RECLAIM_OFF/RECLAIM_ZONE").  So we should revise the description
> here?

Yes, you're right.  I updated the patch with the updated understanding
about the implicit use of the bit but didn't update the changelog.  I'll
do that for v3.