On Tue 15-01-19 19:09:18, Greg KH wrote:
> On Tue, Jan 15, 2019 at 06:40:36PM +0100, Michal Hocko wrote:
> > On Tue 15-01-19 16:51:31, Greg KH wrote:
> > > On Tue, Jan 15, 2019 at 04:34:44PM +0100, Michal Hocko wrote:
> > > > I do not see a straightforward backport of this patch without pulling
> > > > more changes in. Do we have anybody to actually hit the issue on those
> > > > older kernels? While the issue is possible in principle I do not
> > > > remember anybody complaining.
> > >
> > > If no one is complaining, that's fine, you just got this message because
> > > you put this in the commit:
> > >
> > > > > Fixes: c3b94f44fcb0 ("memcg: further prevent OOM with too many dirty pages")
> > >
> > > Which means any kernel newer than 4.2 (and some older stable releases)
> > > has the issue that this patch is trying to fix. If it doesn't need to
> > > be backported that far, wonderful!
> >
> > After a second thought, we are not really affected all the way down to
> > c3b94f44fcb0. We do account page tables to memcgs only since
> > 3e79ec7ddc33 ("arch: x86: charge page tables to kmemcg") 4.8+. Without
> > that there is no realy memcg reclaim and thus not wait_on_page_writeback.
> >
> > So my Fixes is a bit misleading. Sorry about that.
>
> Not a problem, thanks for looking into it. As you say 4.8+, this didn't
> apply to 4.9 either, so do I need to look into doing a manual backport
> there?
Backporting there should be much more easier because we already have
prealloc stuff since 4.8. I will try to find some time to look into this
tomorrow but I am leaving for few days off so I cannot promise anything.
--
Michal Hocko
SUSE Labs
