On Wed, 22 Jun 2016, Joonsoo Kim wrote: > On Tue, Jun 21, 2016 at 04:14:28PM -0700, [email protected] 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 <[email protected]> > > 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/[email protected] > > 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/[email protected] >
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. 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.
