Re: [PATCH] vmpressure: Fix subtree pressure detection

[Vladimir Davydov]

On Thu, Jan 28, 2016 at 08:24:30PM +0100, Vlastimil Babka wrote:
> On 28.1.2016 16:55, Michal Hocko wrote:
> > On Wed 27-01-16 19:28:57, Vladimir Davydov wrote:
> >> When vmpressure is called for the entire subtree under pressure we
> >> mistakenly use vmpressure->scanned instead of vmpressure->tree_scanned
> >> when checking if vmpressure work is to be scheduled. This results in
> >> suppressing all vmpressure events in the legacy cgroup hierarchy. Fix
> >> it.
> >>
> >> Fixes: 8e8ae645249b ("mm: memcontrol: hook up vmpressure to socket pressure")
> >> Signed-off-by: Vladimir Davydov <vdavydov@xxxxxxxxxxxxx>
> > 
> > a = b += c made me scratch my head for a second but this looks correct
> 
> Ugh, it's actually a = b += a
> 
> While clever and compact, this will make scratch their head anyone looking at
> the code in the future. Is it worth it?

I'm just trying to be consistend with the !tree case, where we do
exactly the same.

Thanks,
Vladimir