Re: [PATCH 9/9] mm, page_alloc: optionally disable pcplists during page isolation

Vlastimil Babka
2020-10-05T14:22:53Z

On 10/5/20 4:05 PM, Michal Hocko wrote:
> On Fri 25-09-20 13:10:05, Vlastimil Babka wrote:
>> On 9/25/20 12:54 PM, David Hildenbrand wrote:
>>
>> Hmm that temporary write lock would still block new callers until previous
>> finish with the downgraded-to-read lock.
>>
>> But I guess something like this would work:
>>
>> retry:
>> if (atomic_read(...) == 0) {
>> // zone_update... + drain
>> atomic_inc(...);
>> else if (atomic_inc_return == 1)
>> // atomic_cmpxchg from 0 to 1; if that fails, goto retry
>>
>> Tricky, but races could only read to unnecessary duplicated updates + flushing
>> but nothing worse?
>>
>> Or add another spinlock to cover this part instead of the temp write lock...
>
> Do you plan to post a new version or should I review this one?

I will, hopefully this week, but you could comment on other details and
overall approach meanwhile? I don't think it will change significantly.