Re: [PATCH] mm: remove lock_page_memcg() from rmap

[Hugh Dickins]

On Thu, 1 Dec 2022, Johannes Weiner wrote:
> On Wed, Nov 30, 2022 at 04:13:23PM -0800, Hugh Dickins wrote:
> 
> > And I don't know what will be best for the preliminary precharge pass:
> > doesn't really want the page lock at all, but it may be unnecessary
> > complication to avoid taking it then unlocking it in that pass.
> 
> We could make it conditional on target, which precharge doesn't pass,
> but I agree it's likely not worth optimizing that code at this point.

I hadn't noticed that NULL target so easily distinguishes that case:
unless it goes on to uglify things more (which I think it won't, seeing
now how there are already plenty of conditionals on target), I would
prefer to avoid the trylock and unlock in the precharge case; but
decide for yourself.

Hugh