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SubjectRe: + mm-compaction-split-freepages-without-holding-the-zone-lock-fix.patch added to -mm tree
On Tue, Jun 21, 2016 at 05:53:22PM -0700, David Rientjes wrote:
> On Wed, 22 Jun 2016, Joonsoo Kim wrote:
>
> > On Tue, Jun 21, 2016 at 04:14:28PM -0700, akpm@linux-foundation.org wrote:
> > >
> > > The patch titled
> > > Subject: mm/compaction: split freepages without holding the zone lock fix
> > > has been added to the -mm tree. Its filename is
> > > mm-compaction-split-freepages-without-holding-the-zone-lock-fix.patch
> > >
> > > This patch should soon appear at
> > > http://ozlabs.org/~akpm/mmots/broken-out/mm-compaction-split-freepages-without-holding-the-zone-lock-fix.patch
> > > and later at
> > > http://ozlabs.org/~akpm/mmotm/broken-out/mm-compaction-split-freepages-without-holding-the-zone-lock-fix.patch
> > >
> > > Before you just go and hit "reply", please:
> > > a) Consider who else should be cc'ed
> > > b) Prefer to cc a suitable mailing list as well
> > > c) Ideally: find the original patch on the mailing list and do a
> > > reply-to-all to that, adding suitable additional cc's
> > >
> > > *** Remember to use Documentation/SubmitChecklist when testing your code ***
> > >
> > > The -mm tree is included into linux-next and is updated
> > > there every 3-4 working days
> > >
> > > ------------------------------------------------------
> > > From: David Rientjes <rientjes@google.com>
> > > Subject: mm/compaction: split freepages without holding the zone lock fix
> > >
> > > If __isolate_free_page() fails, avoid adding to freelist so we don't call
> > > map_pages() with it.
> > >
> > > Link: http://lkml.kernel.org/r/alpine.DEB.2.10.1606211447001.43430@chino.kir.corp.google.com
> >
> > I've sent the fix already. I don't care which patch is merged but I guess
> > below series would be merged more cleanly? It's up to Andrew.
> >
> > Link: http://lkml.kernel.org/r/1466150259-27727-1-git-send-email-iamjoonsoo.kim@lge.com
> >
>
> Well, http://marc.info/?l=linux-mm&m=146654572331344 fixes an issue that
> persists at least as far back as 3.11 whereas we can scan entire 256GB+
> zones needlessly each time compaction_alloc() is called, and that function
> can be called multiple times for a single page isolated for migration in
> the case of -EAGAIN. It's been measured that compaction_alloc() can take
> 15-20% of cpu cycles while faulting thp on very large machines back in the
> 3.11 kernel. I would suggest that this is an important fix that needs to
> be included and perhaps backported to stable.

Agreed.

>
> I don't know the relative importance the reducing the size of page_owner
> patchset. It appears that the link you provided is a refreshed series of
> a patchset that is already in -mm? If so, I think the old set should be
> reverted, and whatever dependencies it has, and then a third version of
> http://marc.info/?l=linux-mm&m=146654572331344 merged. I can propose that
> for inclusion in this release cycle if folks agree that it's warranted.
>
> The alternative seems to be to rebase your refreshed series on top of -mm
> with the fix.

I think that page_owner patch is less important. Andrew, could you
revert whole series? I will refresh series on top of -mm with the
David's fix.

Thanks.

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