Re: [PATCH] mm, memcg: do full scan initially in force_empty

Waiman Long
2020-08-03T15:27:06Z

Yafang,

>>
>> > The force_empty will also drop the pagecache pages, which is not
>> > expected by us.
>>
>> force_empty is intended to reclaim _all_ pages.
>>
>> > The global drop_caches can't work either because it will drop slabs in
>> > other memcgs.
>> > That is why I want to introduce per memcg drop_caches.
>>
>> Problems with negative dentries has been already discussed in the past.
>> I believe there was no conclusion so far. Please try to dig into
>> archives.
>
>I have read the proposal of Waiman. But it seems there isn't a conclusion yet.
>If the kernel can't fix this issue perfectly, then giving the user a
>chance to work around it would be a possible solution - drop_caches is
>that kind of workaround.

I am sorry for failing to follow up on the negative dentry patches. Is
your reason of doing this patch primarily because of the negative dentry
build-up? Uncontrollable negative dentry buildup is a problem that should be
addressed. I will work on an updated patch and post it ASAP.

Cheers,
Longman