Re: [PATCH 2/2] mm/page_alloc: fix never set ALLOC_NOFRAGMENT flag
From: Andrew Morton
Date: Thu Apr 25 2019 - 17:09:11 EST
On Thu, 25 Apr 2019 00:40:53 +0100 Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
> On Wed, Apr 24, 2019 at 03:46:24PM -0700, Andrew Morton wrote:
> > On Wed, 24 Apr 2019 10:04:03 +0100 Mel Gorman <mgorman@xxxxxxxxxxxxxxxxxxx> wrote:
> > > On Tue, Apr 23, 2019 at 12:01:43PM -0700, Andrew Morton wrote:
> > > > On Tue, 23 Apr 2019 15:08:06 +0300 Andrey Ryabinin <aryabinin@xxxxxxxxxxxxx> wrote:
> > > >
> > > > > Commit 0a79cdad5eb2 ("mm: use alloc_flags to record if kswapd can wake")
> > > > > removed setting of the ALLOC_NOFRAGMENT flag. Bring it back.
> > > >
> > > > What are the runtime effects of this fix?
> > >
> > > The runtime effect is that ALLOC_NOFRAGMENT behaviour is restored so
> > > that allocations are spread across local zones to avoid fragmentation
> > > due to mixing pageblocks as long as possible.
> > OK, thanks. Is this worth a -stable backport?
> Yes, but only for 5.0 obviously and both should be included if that is
> the case. I did not push for it initially as problems in this area are
> hard for a general user to detect and people have not complained about
> 5.0's fragmentation handling.
Ah, OK. 0a79cdad5eb2 didn't have a -stable tag so I suppose we can
leave this patch un-stabled.
If they went and backported 0a79cdad5eb2 anyway, let's hope the scripts
are smart enough to catch this patch's Fixes: link.