Re: [RFC][PATCH 7/6] memcg: add atribute (for change bahavior ofrmdir)

[Hugh Dickins]

On Thu, 6 Nov 2008, KAMEZAWA Hiroyuki wrote:
> On Thu, 06 Nov 2008 12:24:11 +0530
> Balbir Singh <balbir@xxxxxxxxxxxxxxxxxx> wrote:
> > KAMEZAWA Hiroyuki wrote:
> > > 
> > > 1. change force_empty to do move account rather than forget all
> > 
> > I would like this to be selectable, please. We don't want to break behaviour and
> > not everyone would like to pay the cost of movement.
> 
> How about a patch like this ? I'd like to move this as [2/7], if possible.
> It obviously needs painful rework. If I found it difficult, schedule this as [7/7].
> 
> BTW, cost of movement itself is not far from cost for force_empty.
> 
> If you can't find why "forget" is bad, please consider one more day.

My recollection from a year ago is that force_empty totally violated
the rules established elsewhere, making a nonsense of it all: once a
force_empty had been done, you couldn't really be sure of anything
(perhaps it deserved a Taint flag).

Without studying your proposals at all, I do believe you've a good
chance of creating a sensible and consistent force_empty by moving
account, and abandoning the old "forget all" approach completely.

Hugh
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