From: Michal Hocko <mhocko@kernel.org>
To: Vlastimil Babka <vbabka@suse.cz>
Cc: linux-mm@kvack.org, Andrew Morton <akpm@linux-foundation.org>,
Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH 7/9] mm, page_alloc: remove stop_machine from build_all_zonelists
Date: Thu, 20 Jul 2017 11:21:25 +0200 [thread overview]
Message-ID: <20170720092124.GG9058@dhcp22.suse.cz> (raw)
In-Reply-To: <8d9d4eb5-eb7e-0422-0464-cdea9cb7e849@suse.cz>
On Thu 20-07-17 09:24:58, Vlastimil Babka wrote:
> On 07/14/2017 10:00 AM, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> >
> > build_all_zonelists has been (ab)using stop_machine to make sure that
> > zonelists do not change while somebody is looking at them. This is
> > is just a gross hack because a) it complicates the context from which
> > we can call build_all_zonelists (see 3f906ba23689 ("mm/memory-hotplug:
> > switch locking to a percpu rwsem")) and b) is is not really necessary
> > especially after "mm, page_alloc: simplify zonelist initialization".
> >
> > Updates of the zonelists happen very seldom, basically only when a zone
> > becomes populated during memory online or when it loses all the memory
> > during offline. A racing iteration over zonelists could either miss a
> > zone or try to work on one zone twice. Both of these are something we
> > can live with occasionally because there will always be at least one
> > zone visible so we are not likely to fail allocation too easily for
> > example.
> >
> > Signed-off-by: Michal Hocko <mhocko@suse.com>
>
> Some stress testing of this would still be worth, IMHO.
I have run the pathological online/offline of the single memblock in the
movable zone while stressing the same small node with some memory pressure.
Node 1, zone DMA
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 943, 943, 943)
Node 1, zone DMA32
pages free 227310
min 8294
low 10367
high 12440
spanned 262112
present 262112
managed 241436
protection: (0, 0, 0, 0)
Node 1, zone Normal
pages free 0
min 0
low 0
high 0
spanned 0
present 0
managed 0
protection: (0, 0, 0, 1024)
Node 1, zone Movable
pages free 32722
min 85
low 117
high 149
spanned 32768
present 32768
managed 32768
protection: (0, 0, 0, 0)
root@test1:/sys/devices/system/node/node1# while true
do
echo offline > memory34/state
echo online_movable > memory34/state
done
root@test1:/mnt/data/test/linux-3.7-rc5# numactl --preferred=1 make -j4
and it survived without any unexpected behavior. While this is not
really a great testing coverage it should exercise the allocation path
quite a lot.
I can add this to the changelog if you think it is worth it.
> Acked-by: Vlastimil Babka <vbabka@suse.cz>
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2017-07-20 9:21 UTC|newest]
Thread overview: 54+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-14 7:59 [PATCH 0/9] cleanup zonelists initialization Michal Hocko
2017-07-14 7:59 ` [PATCH 1/9] mm, page_alloc: rip out ZONELIST_ORDER_ZONE Michal Hocko
2017-07-14 9:36 ` Mel Gorman
2017-07-14 10:47 ` Michal Hocko
2017-07-14 11:16 ` Mel Gorman
2017-07-14 11:38 ` Michal Hocko
2017-07-14 12:56 ` Mel Gorman
2017-07-14 13:01 ` Mel Gorman
2017-07-14 13:08 ` Michal Hocko
2017-07-19 9:33 ` Vlastimil Babka
2017-07-19 13:44 ` Michal Hocko
2017-07-14 7:59 ` [PATCH 2/9] mm, page_alloc: remove boot pageset initialization from memory hotplug Michal Hocko
2017-07-14 9:39 ` Mel Gorman
2017-07-19 13:15 ` Vlastimil Babka
2017-07-14 8:00 ` [PATCH 3/9] mm, page_alloc: do not set_cpu_numa_mem on empty nodes initialization Michal Hocko
2017-07-14 9:48 ` Mel Gorman
2017-07-14 10:50 ` Michal Hocko
2017-07-14 12:32 ` Mel Gorman
2017-07-14 12:39 ` Michal Hocko
2017-07-14 12:56 ` Mel Gorman
2017-07-19 13:19 ` Vlastimil Babka
2017-07-14 8:00 ` [PATCH 4/9] mm, memory_hotplug: drop zone from build_all_zonelists Michal Hocko
2017-07-19 13:33 ` Vlastimil Babka
2017-07-20 8:15 ` Michal Hocko
2017-07-14 8:00 ` [PATCH 5/9] mm, memory_hotplug: remove explicit build_all_zonelists from try_online_node Michal Hocko
2017-07-14 12:14 ` Michal Hocko
2017-07-20 6:13 ` Vlastimil Babka
2017-07-14 8:00 ` [PATCH 6/9] mm, page_alloc: simplify zonelist initialization Michal Hocko
2017-07-14 9:55 ` Mel Gorman
2017-07-14 10:51 ` Michal Hocko
2017-07-14 12:46 ` Mel Gorman
2017-07-14 13:02 ` Michal Hocko
2017-07-14 14:18 ` Mel Gorman
2017-07-17 6:06 ` Michal Hocko
2017-07-17 8:07 ` Mel Gorman
2017-07-17 8:19 ` Michal Hocko
2017-07-17 8:58 ` Mel Gorman
2017-07-17 9:15 ` Michal Hocko
2017-07-20 6:55 ` Vlastimil Babka
2017-07-20 7:19 ` Michal Hocko
2017-07-14 8:00 ` [PATCH 7/9] mm, page_alloc: remove stop_machine from build_all_zonelists Michal Hocko
2017-07-14 9:59 ` Mel Gorman
2017-07-14 11:00 ` Michal Hocko
2017-07-14 12:47 ` Mel Gorman
2017-07-14 11:29 ` Vlastimil Babka
2017-07-14 11:43 ` Michal Hocko
2017-07-14 11:45 ` Michal Hocko
2017-07-20 6:16 ` Vlastimil Babka
2017-07-20 7:24 ` Vlastimil Babka
2017-07-20 9:21 ` Michal Hocko [this message]
2017-07-14 8:00 ` [PATCH 8/9] mm, memory_hotplug: get rid of zonelists_mutex Michal Hocko
2017-07-14 8:00 ` [PATCH 9/9] mm, sparse, page_ext: drop ugly N_HIGH_MEMORY branches for allocations Michal Hocko
2017-07-20 8:04 ` Vlastimil Babka
2017-07-21 14:39 [PATCH -v1 0/9] cleanup zonelists initialization Michal Hocko
2017-07-21 14:39 ` [PATCH 7/9] mm, page_alloc: remove stop_machine from build_all_zonelists Michal Hocko
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