From: Vlastimil Babka <vbabka@suse.cz>
To: Michal Hocko <mhocko@kernel.org>,
Andrew Morton <akpm@linux-foundation.org>
Cc: Mel Gorman <mgorman@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
linux-mm@kvack.org, LKML <linux-kernel@vger.kernel.org>,
Michal Hocko <mhocko@suse.com>
Subject: Re: [PATCH 6/9] mm, page_alloc: simplify zonelist initialization
Date: Mon, 24 Jul 2017 11:25:47 +0200 [thread overview]
Message-ID: <994c1d72-bc57-1378-586d-fdfce770e53e@suse.cz> (raw)
In-Reply-To: <20170721143915.14161-7-mhocko@kernel.org>
On 07/21/2017 04:39 PM, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
>
> build_zonelists gradually builds zonelists from the nearest to the most
> distant node. As we do not know how many populated zones we will have in
> each node we rely on the _zoneref to terminate initialized part of the
> zonelist by a NULL zone. While this is functionally correct it is quite
> suboptimal because we cannot allow updaters to race with zonelists
> users because they could see an empty zonelist and fail the allocation
> or hit the OOM killer in the worst case.
>
> We can do much better, though. We can store the node ordering into an
> already existing node_order array and then give this array to
> build_zonelists_in_node_order and do the whole initialization at once.
> zonelists consumers still might see halfway initialized state but that
> should be much more tolerateable because the list will not be empty and
> they would either see some zone twice or skip over some zone(s) in the
> worst case which shouldn't lead to immediate failures.
>
> While at it let's simplify build_zonelists_node which is rather
> confusing now. It gets an index into the zoneref array and returns
> the updated index for the next iteration. Let's rename the function
> to build_zonerefs_node to better reflect its purpose and give it
> zoneref array to update. The function doesn't the index anymore. It
> just returns the number of added zones so that the caller can advance
> the zonered array start for the next update.
>
> This patch alone doesn't introduce any functional change yet, though, it
> is merely a preparatory work for later changes.
>
> Changes since v1
> - build_zonelists_node -> build_zonerefs_node and operate directly on
> zonerefs array rather than play tricks with index into the array.
> - give build_zonelists_in_node_order nr_nodes to not iterate over all
> MAX_NUMNODES as per Mel
>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
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next prev parent reply other threads:[~2017-07-24 9:25 UTC|newest]
Thread overview: 25+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-07-21 14:39 [PATCH -v1 0/9] cleanup zonelists initialization Michal Hocko
2017-07-21 14:39 ` [PATCH 1/9] mm, page_alloc: rip out ZONELIST_ORDER_ZONE Michal Hocko
2017-07-21 14:45 ` Michal Hocko
2017-07-21 14:39 ` [PATCH 2/9] mm, page_alloc: remove boot pageset initialization from memory hotplug Michal Hocko
2017-07-21 14:39 ` [PATCH 3/9] mm, page_alloc: do not set_cpu_numa_mem on empty nodes initialization Michal Hocko
2017-07-21 14:39 ` [PATCH 4/9] mm, memory_hotplug: drop zone from build_all_zonelists Michal Hocko
2017-07-21 14:39 ` [PATCH 5/9] mm, memory_hotplug: remove explicit build_all_zonelists from try_online_node Michal Hocko
2017-07-21 14:39 ` [PATCH 6/9] mm, page_alloc: simplify zonelist initialization Michal Hocko
2017-07-24 9:25 ` Vlastimil Babka [this message]
2017-07-21 14:39 ` [PATCH 7/9] mm, page_alloc: remove stop_machine from build_all_zonelists Michal Hocko
2017-07-21 14:39 ` [PATCH 8/9] mm, memory_hotplug: get rid of zonelists_mutex Michal Hocko
2017-07-21 14:39 ` [PATCH 9/9] mm, sparse, page_ext: drop ugly N_HIGH_MEMORY branches for allocations Michal Hocko
-- strict thread matches above, loose matches on Subject: below --
2017-07-14 7:59 [PATCH 0/9] cleanup zonelists initialization Michal Hocko
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
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