From: David Rientjes <rientjes@google.com>
To: Michal Hocko <mhocko@kernel.org>
Cc: Vlastimil Babka <vbabka@suse.cz>,
Linus Torvalds <torvalds@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>,
Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
Linux Kernel Mailing List <linux-kernel@vger.kernel.org>,
Linux-MM <linux-mm@kvack.org>
Subject: Re: [patch for-5.3 0/4] revert immediate fallback to remote hugepages
Date: Wed, 2 Oct 2019 15:32:20 -0700 (PDT) [thread overview]
Message-ID: <alpine.DEB.2.21.1910021525180.63052@chino.kir.corp.google.com> (raw)
In-Reply-To: <20191002103422.GJ15624@dhcp22.suse.cz>
On Wed, 2 Oct 2019, Michal Hocko wrote:
> > > If
> > > hugetlb wants to stress this to the fullest extent possible, it already
> > > appropriately uses __GFP_RETRY_MAYFAIL.
> >
> > Which doesn't work anymore right now, and should again after this patch.
>
> I didn't get to fully digest the patch Vlastimil is proposing. (Ab)using
> __GFP_NORETRY is quite subtle but it is already in place with some
> explanation and a reference to THPs. So while I am not really happy it
> is at least something you can reason about.
>
It's a no-op:
/* Do not loop if specifically requested */
if (gfp_mask & __GFP_NORETRY)
goto nopage;
/*
* Do not retry costly high order allocations unless they are
* __GFP_RETRY_MAYFAIL
*/
if (costly_order && !(gfp_mask & __GFP_RETRY_MAYFAIL))
goto nopage;
So I'm not sure we should spend too much time discussing a hunk of a patch
that doesn't do anything.
> b39d0ee2632d ("mm, page_alloc: avoid expensive reclaim when compaction
> may not succeed") on the other hand has added a much more wider change
> which has clearly broken hugetlb and any __GFP_RETRY_MAYFAIL user of
> pageblock_order sized allocations. And that is much worse and something
> I was pointing at during the review and those concerns were never really
> addressed before merging.
>
> In any case this is something to be fixed ASAP. Do you have any better
> proposa? I do not assume you would be proposing yet another revert.
I thought Mike Kravetz said[*] that hugetlb was not negatively affected by
this? We could certainly disregard this logic for __GFP_RETRY_MAYFAIL if
anybody is relying on excessive reclaim ("swap storms") that does not
allow compaction to make forward progress for some reason.
[*] https://marc.info/?l=linux-kernel&m=156771690024533
If not, for the purposes of this conversation we can disregard
__GFP_NORETRY per the above because thp does not use __GFP_RETRY_MAYFAIL.
next prev parent reply other threads:[~2019-10-02 22:32 UTC|newest]
Thread overview: 49+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-09-04 19:54 David Rientjes
2019-09-04 19:54 ` [rfc 3/4] mm, page_alloc: avoid expensive reclaim when compaction may not succeed David Rientjes
2019-09-05 9:00 ` Michal Hocko
2019-09-05 11:22 ` Vlastimil Babka
2019-09-05 20:53 ` Mike Kravetz
2019-09-06 20:16 ` David Rientjes
2019-09-06 20:49 ` David Rientjes
2019-09-04 20:43 ` [patch for-5.3 0/4] revert immediate fallback to remote hugepages Linus Torvalds
2019-09-05 20:54 ` David Rientjes
2019-09-07 19:51 ` David Rientjes
2019-09-07 19:55 ` Linus Torvalds
2019-09-08 1:50 ` David Rientjes
2019-09-08 12:47 ` Vlastimil Babka
2019-09-08 20:45 ` David Rientjes
2019-09-09 8:37 ` Michal Hocko
2019-09-04 20:55 ` Andrea Arcangeli
2019-09-05 21:06 ` David Rientjes
2019-09-09 19:30 ` Michal Hocko
2019-09-25 7:08 ` Michal Hocko
2019-09-26 19:03 ` David Rientjes
2019-09-27 7:48 ` Michal Hocko
2019-09-28 20:59 ` Linus Torvalds
2019-09-30 11:28 ` Michal Hocko
2019-10-01 5:43 ` Michal Hocko
2019-10-01 8:37 ` Michal Hocko
2019-10-18 14:15 ` Michal Hocko
2019-10-23 11:03 ` Vlastimil Babka
2019-10-24 18:59 ` David Rientjes
2019-10-29 14:14 ` Vlastimil Babka
2019-10-29 15:15 ` Michal Hocko
2019-10-29 21:33 ` Andrew Morton
2019-10-29 21:45 ` Vlastimil Babka
2019-10-29 23:25 ` David Rientjes
2019-11-05 13:02 ` Michal Hocko
2019-11-06 1:01 ` David Rientjes
2019-11-06 7:35 ` Michal Hocko
2019-11-06 21:32 ` David Rientjes
2019-11-13 11:20 ` Mel Gorman
2019-11-25 0:10 ` David Rientjes
2019-11-25 11:47 ` Michal Hocko
2019-11-25 20:38 ` David Rientjes
2019-11-25 21:34 ` Vlastimil Babka
2019-10-01 13:50 ` Vlastimil Babka
2019-10-01 20:31 ` David Rientjes
2019-10-01 21:54 ` Vlastimil Babka
2019-10-02 10:34 ` Michal Hocko
2019-10-02 22:32 ` David Rientjes [this message]
2019-10-03 8:00 ` Vlastimil Babka
2019-10-04 12:18 ` Michal Hocko
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