From: Michal Hocko <mhocko@kernel.org>
To: Mel Gorman <mgorman@techsingularity.net>
Cc: Srikar Dronamraju <srikar@linux.vnet.ibm.com>,
Andrew Morton <akpm@linux-foundation.org>,
Linux-MM <linux-mm@kvack.org>, Rik van Riel <riel@surriel.com>,
Vlastimil Babka <vbabka@suse.cz>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan@kernel.org>,
Joonsoo Kim <iamjoonsoo.kim@lge.com>,
LKML <linux-kernel@vger.kernel.org>,
Michael Ellerman <mpe@ellerman.id.au>,
linuxppc-dev@lists.ozlabs.org,
Mahesh Salgaonkar <mahesh@linux.vnet.ibm.com>,
Hari Bathini <hbathini@linux.vnet.ibm.com>
Subject: Re: [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes
Date: Wed, 31 Aug 2016 13:09:33 +0200 [thread overview]
Message-ID: <20160831110932.GB21661@dhcp22.suse.cz> (raw)
In-Reply-To: <20160831084942.GX8119@techsingularity.net>
On Wed 31-08-16 09:49:42, Mel Gorman wrote:
> On Wed, Aug 31, 2016 at 11:39:59AM +0530, Srikar Dronamraju wrote:
> > This indeed fixes the problem.
> > Please add my
> > Tested-by: Srikar Dronamraju <srikar@linux.vnet.ibm.com>
> >
>
> Ok, thanks. Unfortunately we cannot do a wide conversion like this
> because some users of populated_zone() really meant to check for
> present_pages. In all cases, the expectation was that reserved pages
> would be tiny but fadump messes that up. Can you verify this also works
> please?
>
> ---8<---
> mm, vmscan: Only allocate and reclaim from zones with pages managed by the buddy allocator
>
> Firmware Assisted Dump (FA_DUMP) on ppc64 reserves substantial amounts
> of memory when booting a secondary kernel. Srikar Dronamraju reported that
> multiple nodes may have no memory managed by the buddy allocator but still
> return true for populated_zone().
>
> Commit 1d82de618ddd ("mm, vmscan: make kswapd reclaim in terms of nodes")
> was reported to cause kswapd to spin at 100% CPU usage when fadump was
> enabled. The old code happened to deal with the situation of a populated
> node with zero free pages by co-incidence but the current code tries to
> reclaim populated zones without realising that is impossible.
>
> We cannot just convert populated_zone() as many existing users really
> need to check for present_pages. This patch introduces a managed_zone()
> helper and uses it in the few cases where it is critical that the check
> is made for managed pages -- zonelist constuction and page reclaim.
OK, the patch makes sense to me. I am not happy about two very similar
functions, to be honest though. managed vs. present checks will be quite
subtle and it is not entirely clear when to use which one. I agree that
the reclaim path is the most critical one so the patch seems OK to me.
At least from a quick glance it should help with the reported issue so
feel free to add
Acked-by: Michal Hocko <mhocko@suse.com>
I expect we might want to turn other places as well but they are far
from critical. I would appreciate some lead there and stick a clarifying
comment
[...]
> -static inline int populated_zone(struct zone *zone)
> +/* Returns true if a zone has pages managed by the buddy allocator */
/*
* Returns true if a zone has pages managed by the buddy allocator.
* All the reclaim decisions have to use this function rather than
* populated_zone(). If the whole zone is reserved then we can easily
* end up with populated_zone() && !managed_zone().
*/
What do you think?
> +static inline bool managed_zone(struct zone *zone)
> {
> - return (!!zone->present_pages);
> + return zone->managed_pages;
> +}
> +
> +/* Returns true if a zone has memory */
> +static inline bool populated_zone(struct zone *zone)
> +{
> + return zone->present_pages;
> }
--
Michal Hocko
SUSE Labs
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next prev parent reply other threads:[~2016-08-31 11:09 UTC|newest]
Thread overview: 109+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-07-08 9:34 [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Mel Gorman
2016-07-08 9:34 ` [PATCH 01/34] mm, vmstat: add infrastructure for per-node vmstats Mel Gorman
2016-08-03 19:13 ` Reza Arbab
2016-07-08 9:34 ` [PATCH 02/34] mm, vmscan: move lru_lock to the node Mel Gorman
2016-07-12 11:06 ` Balbir Singh
2016-07-12 11:18 ` Mel Gorman
2016-07-13 5:50 ` Balbir Singh
2016-07-13 8:39 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 03/34] mm, vmscan: move LRU lists to node Mel Gorman
2016-08-04 20:59 ` James Hogan
2016-08-05 8:41 ` Mel Gorman
2016-08-05 10:52 ` James Hogan
2016-08-05 11:55 ` Mel Gorman
2016-08-05 12:02 ` James Hogan
2016-07-08 9:34 ` [PATCH 04/34] mm, mmzone: clarify the usage of zone padding Mel Gorman
2016-07-12 13:49 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 05/34] mm, vmscan: begin reclaiming pages on a per-node basis Mel Gorman
2016-07-12 13:54 ` Johannes Weiner
2016-07-14 9:19 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 06/34] mm, vmscan: have kswapd only scan based on the highest requested zone Mel Gorman
2016-07-12 14:05 ` Johannes Weiner
2016-07-13 8:37 ` Mel Gorman
2016-07-08 9:34 ` [PATCH 07/34] mm, vmscan: make kswapd reclaim in terms of nodes Mel Gorman
2016-08-29 9:38 ` Srikar Dronamraju
2016-08-30 12:07 ` Mel Gorman
2016-08-30 14:25 ` Srikar Dronamraju
2016-08-30 15:00 ` Mel Gorman
2016-08-31 6:09 ` Srikar Dronamraju
2016-08-31 8:49 ` Mel Gorman
2016-08-31 11:09 ` Michal Hocko [this message]
2016-08-31 12:46 ` Mel Gorman
2016-08-31 17:33 ` Srikar Dronamraju
2016-07-08 9:34 ` [PATCH 08/34] mm, vmscan: remove balance gap Mel Gorman
2016-07-12 14:06 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 09/34] mm, vmscan: simplify the logic deciding whether kswapd sleeps Mel Gorman
2016-07-08 9:34 ` [PATCH 10/34] mm, vmscan: by default have direct reclaim only shrink once per node Mel Gorman
2016-07-08 9:34 ` [PATCH 11/34] mm, vmscan: remove duplicate logic clearing node congestion and dirty state Mel Gorman
2016-07-12 14:22 ` Johannes Weiner
2016-07-13 8:40 ` Mel Gorman
2016-07-14 9:45 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 12/34] mm: vmscan: do not reclaim from kswapd if there is any eligible zone Mel Gorman
2016-07-12 14:29 ` Johannes Weiner
2016-07-13 8:47 ` Mel Gorman
2016-07-13 12:28 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 13/34] mm, vmscan: make shrink_node decisions more node-centric Mel Gorman
2016-07-12 14:32 ` Johannes Weiner
2016-07-13 8:48 ` Mel Gorman
2016-07-08 9:34 ` [PATCH 14/34] mm, memcg: move memcg limit enforcement from zones to nodes Mel Gorman
2016-07-12 14:38 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 15/34] mm, workingset: make working set detection node-aware Mel Gorman
2016-07-08 9:34 ` [PATCH 16/34] mm, page_alloc: consider dirtyable memory in terms of nodes Mel Gorman
2016-07-08 9:34 ` [PATCH 17/34] mm: move page mapped accounting to the node Mel Gorman
2016-07-12 14:42 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 18/34] mm: rename NR_ANON_PAGES to NR_ANON_MAPPED Mel Gorman
2016-07-12 14:58 ` Johannes Weiner
2016-07-13 8:55 ` Mel Gorman
2016-07-13 13:04 ` Johannes Weiner
2016-07-13 13:37 ` Mel Gorman
2016-07-13 21:13 ` Andrew Morton
2016-07-15 10:46 ` Mel Gorman
2016-07-15 22:35 ` Andrew Morton
2016-07-18 13:34 ` Johannes Weiner
2016-07-14 1:27 ` Minchan Kim
2016-07-08 9:34 ` [PATCH 19/34] mm: move most file-based accounting to the node Mel Gorman
2016-07-12 15:11 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 20/34] mm: move vmscan writes and file write " Mel Gorman
2016-07-12 15:15 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 21/34] mm, vmscan: only wakeup kswapd once per node for the requested classzone Mel Gorman
2016-07-12 17:18 ` Johannes Weiner
2016-07-08 9:34 ` [PATCH 22/34] mm, page_alloc: wake kswapd based on the highest eligible zone Mel Gorman
2016-07-12 17:24 ` Johannes Weiner
2016-07-14 10:05 ` Vlastimil Babka
2016-07-08 9:34 ` [PATCH 23/34] mm: convert zone_reclaim to node_reclaim Mel Gorman
2016-07-12 17:28 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 24/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to shrink_node Mel Gorman
2016-07-12 17:31 ` Johannes Weiner
2016-07-14 10:09 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 25/34] mm, vmscan: avoid passing in classzone_idx unnecessarily to compaction_ready Mel Gorman
2016-07-12 18:01 ` Johannes Weiner
2016-07-14 12:12 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 26/34] mm, vmscan: avoid passing in remaining unnecessarily to prepare_kswapd_sleep Mel Gorman
2016-07-12 18:06 ` Johannes Weiner
2016-07-14 12:48 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 27/34] mm, vmscan: Have kswapd reclaim from all zones if reclaiming and buffer_heads_over_limit Mel Gorman
2016-07-12 18:10 ` Johannes Weiner
2016-07-14 12:54 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 28/34] mm, vmscan: add classzone information to tracepoints Mel Gorman
2016-07-12 18:13 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 29/34] mm, page_alloc: remove fair zone allocation policy Mel Gorman
2016-07-12 18:18 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 30/34] mm: page_alloc: cache the last node whose dirty limit is reached Mel Gorman
2016-07-12 18:43 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 31/34] mm: vmstat: replace __count_zone_vm_events with a zone id equivalent Mel Gorman
2016-07-12 19:10 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 32/34] mm: vmstat: account per-zone stalls and pages skipped during reclaim Mel Gorman
2016-07-12 19:06 ` Johannes Weiner
2016-07-08 9:35 ` [PATCH 33/34] mm, vmstat: print node-based stats in zoneinfo file Mel Gorman
2016-07-12 19:18 ` Johannes Weiner
2016-07-14 12:56 ` Vlastimil Babka
2016-07-08 9:35 ` [PATCH 34/34] mm, vmstat: remove zone and node double accounting by approximating retries Mel Gorman
2016-07-14 13:40 ` Vlastimil Babka
2016-07-15 7:48 ` Mel Gorman
2016-07-15 12:20 ` Vlastimil Babka
2016-08-19 13:12 ` [PATCH 00/34] Move LRU page reclaim from zones to nodes v9 Andrea Arcangeli
2016-08-19 13:23 ` Vlastimil Babka
2016-08-19 13:55 ` Andrea Arcangeli
2016-08-19 14:53 ` Mel Gorman
2016-08-19 15:32 ` Andrea Arcangeli
2016-08-19 15:55 ` Mel Gorman
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