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* [RFC PATCH 0/2] follow up nodereclaim for 32b fix
@ 2017-01-10 12:55 Michal Hocko
  2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
  2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
  0 siblings, 2 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-10 12:55 UTC (permalink / raw)
  To: linux-mm; +Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Andrew Morton

Hi,
this is a follow up fix on top of [1]. I wasn't able to trigger bad
things happening without the patch but the fix should be quite obvious
and should make sense in general. I am sending this as an RFC, though,
because g_u_p is better to not touch without strong reasons because it
is just too easy to screw up.

The second patch is just a cleanup on top.

[1] http://lkml.kernel.org/r/20170104100825.3729-1-mhocko@kernel.org

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-10 12:55 [RFC PATCH 0/2] follow up nodereclaim for 32b fix Michal Hocko
@ 2017-01-10 12:55 ` Michal Hocko
  2017-01-11  6:18   ` Hillf Danton
                     ` (2 more replies)
  2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
  1 sibling, 3 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-10 12:55 UTC (permalink / raw)
  To: linux-mm
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Andrew Morton, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

get_scan_count considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan

in both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.

A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.

The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
at maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.

Changes since v1
- s@lruvec_lru_size_zone_idx@lruvec_lru_size_eligibe_zones@

Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 30 ++++++++++++++++++++++++++++--
 1 file changed, 28 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 069eb637f5f3..137bc85067d3 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -253,6 +253,32 @@ unsigned long lruvec_zone_lru_size(struct lruvec *lruvec, enum lru_list lru,
 }
 
 /*
+ * Return the number of pages on the given lru which are eligible for the
+ * given zone_idx
+ */
+static unsigned long lruvec_lru_size_eligibe_zones(struct lruvec *lruvec,
+		enum lru_list lru, int zone_idx)
+{
+	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
+	unsigned long lru_size;
+	int zid;
+
+	lru_size = lruvec_lru_size(lruvec, lru);
+	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
+		struct zone *zone = &pgdat->node_zones[zid];
+		unsigned long size;
+
+		if (!managed_zone(zone))
+			continue;
+
+		size = lruvec_zone_lru_size(lruvec, lru, zid);
+		lru_size -= min(size, lru_size);
+	}
+
+	return lru_size;
+}
+
+/*
  * Add a shrinker callback to be called from the vm.
  */
 int register_shrinker(struct shrinker *shrinker)
@@ -2213,7 +2239,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) {
+	    lruvec_lru_size_eligibe_zones(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2280,7 +2306,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru);
+			size = lruvec_lru_size_eligibe_zones(lruvec, lru, sc->reclaim_idx);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
-- 
2.11.0

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^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low
  2017-01-10 12:55 [RFC PATCH 0/2] follow up nodereclaim for 32b fix Michal Hocko
  2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
@ 2017-01-10 12:55 ` Michal Hocko
  2017-01-10 23:56   ` Minchan Kim
                     ` (2 more replies)
  1 sibling, 3 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-10 12:55 UTC (permalink / raw)
  To: linux-mm
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Andrew Morton, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

inactive_list_is_low is duplicating logic implemented by
lruvec_lru_size_eligibe_zones. Let's use the dedicated function to get
the number of eligible pages on the lru list and ask use lruvec_lru_size
to get the total LRU lize only when the tracing is really requested. We
are still iterating over all LRUs two times in that case but a)
inactive_list_is_low is not a hot path and b) this can be addressed at
the tracing layer and only evaluate arguments only when the tracing is
enabled in future if that ever matters.

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 38 ++++++++++----------------------------
 1 file changed, 10 insertions(+), 28 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 137bc85067d3..a9c881f06c0e 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2054,11 +2054,10 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 						struct scan_control *sc, bool trace)
 {
 	unsigned long inactive_ratio;
-	unsigned long total_inactive, inactive;
-	unsigned long total_active, active;
+	unsigned long inactive, active;
+	enum lru_list inactive_lru = file * LRU_FILE;
+	enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE;
 	unsigned long gb;
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-	int zid;
 
 	/*
 	 * If we don't have swap space, anonymous page deactivation
@@ -2067,27 +2066,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 	if (!file && !total_swap_pages)
 		return false;
 
-	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
-	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
-
-	/*
-	 * For zone-constrained allocations, it is necessary to check if
-	 * deactivations are required for lowmem to be reclaimed. This
-	 * calculates the inactive/active pages available in eligible zones.
-	 */
-	for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {
-		struct zone *zone = &pgdat->node_zones[zid];
-		unsigned long inactive_zone, active_zone;
-
-		if (!managed_zone(zone))
-			continue;
-
-		inactive_zone = lruvec_zone_lru_size(lruvec, file * LRU_FILE, zid);
-		active_zone = lruvec_zone_lru_size(lruvec, (file * LRU_FILE) + LRU_ACTIVE, zid);
-
-		inactive -= min(inactive, inactive_zone);
-		active -= min(active, active_zone);
-	}
+	inactive = lruvec_lru_size_eligibe_zones(lruvec, inactive_lru, sc->reclaim_idx);
+	active = lruvec_lru_size_eligibe_zones(lruvec, active_lru, sc->reclaim_idx);
 
 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
 	if (gb)
@@ -2096,10 +2076,12 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 		inactive_ratio = 1;
 
 	if (trace)
-		trace_mm_vmscan_inactive_list_is_low(pgdat->node_id,
+		trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id,
 				sc->reclaim_idx,
-				total_inactive, inactive,
-				total_active, active, inactive_ratio, file);
+				lruvec_lru_size(lruvec, inactive_lru), inactive,
+				lruvec_lru_size(lruvec, active_lru), active,
+				inactive_ratio, file);
+
 	return inactive * inactive_ratio < active;
 }
 
-- 
2.11.0

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^ permalink raw reply related	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low
  2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
@ 2017-01-10 23:56   ` Minchan Kim
  2017-01-11  6:22   ` Hillf Danton
  2017-01-14 16:16   ` Johannes Weiner
  2 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-10 23:56 UTC (permalink / raw)
  To: Michal Hocko
  Cc: linux-mm, Johannes Weiner, Mel Gorman, Andrew Morton, Michal Hocko

Hi Michal,

On Tue, Jan 10, 2017 at 01:55:52PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> inactive_list_is_low is duplicating logic implemented by
> lruvec_lru_size_eligibe_zones. Let's use the dedicated function to get
> the number of eligible pages on the lru list and ask use lruvec_lru_size
> to get the total LRU lize only when the tracing is really requested. We
> are still iterating over all LRUs two times in that case but a)
> inactive_list_is_low is not a hot path and b) this can be addressed at
> the tracing layer and only evaluate arguments only when the tracing is
> enabled in future if that ever matters.

Make sense so I was about to add my acked-by but surprised when I found
"bool trace variable" and lruvec_lru_size in the trace so I ask some
questions to the "+ mm-vmscan-add-mm_vmscan_inactive_list_is_low-tracepoint"
thread.

Except that part, looks good to me.

> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/vmscan.c | 38 ++++++++++----------------------------
>  1 file changed, 10 insertions(+), 28 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index 137bc85067d3..a9c881f06c0e 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2054,11 +2054,10 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
>  						struct scan_control *sc, bool trace)
>  {
>  	unsigned long inactive_ratio;
> -	unsigned long total_inactive, inactive;
> -	unsigned long total_active, active;
> +	unsigned long inactive, active;
> +	enum lru_list inactive_lru = file * LRU_FILE;
> +	enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE;
>  	unsigned long gb;
> -	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> -	int zid;
>  
>  	/*
>  	 * If we don't have swap space, anonymous page deactivation
> @@ -2067,27 +2066,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
>  	if (!file && !total_swap_pages)
>  		return false;
>  
> -	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
> -	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
> -
> -	/*
> -	 * For zone-constrained allocations, it is necessary to check if
> -	 * deactivations are required for lowmem to be reclaimed. This
> -	 * calculates the inactive/active pages available in eligible zones.
> -	 */
> -	for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {
> -		struct zone *zone = &pgdat->node_zones[zid];
> -		unsigned long inactive_zone, active_zone;
> -
> -		if (!managed_zone(zone))
> -			continue;
> -
> -		inactive_zone = lruvec_zone_lru_size(lruvec, file * LRU_FILE, zid);
> -		active_zone = lruvec_zone_lru_size(lruvec, (file * LRU_FILE) + LRU_ACTIVE, zid);
> -
> -		inactive -= min(inactive, inactive_zone);
> -		active -= min(active, active_zone);
> -	}
> +	inactive = lruvec_lru_size_eligibe_zones(lruvec, inactive_lru, sc->reclaim_idx);
> +	active = lruvec_lru_size_eligibe_zones(lruvec, active_lru, sc->reclaim_idx);
>  
>  	gb = (inactive + active) >> (30 - PAGE_SHIFT);
>  	if (gb)
> @@ -2096,10 +2076,12 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
>  		inactive_ratio = 1;
>  
>  	if (trace)
> -		trace_mm_vmscan_inactive_list_is_low(pgdat->node_id,
> +		trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id,
>  				sc->reclaim_idx,
> -				total_inactive, inactive,
> -				total_active, active, inactive_ratio, file);
> +				lruvec_lru_size(lruvec, inactive_lru), inactive,
> +				lruvec_lru_size(lruvec, active_lru), active,
> +				inactive_ratio, file);
> +
>  	return inactive * inactive_ratio < active;
>  }
>  
> -- 
> 2.11.0
> 
> --
> To unsubscribe, send a message with 'unsubscribe linux-mm' in
> the body to majordomo@kvack.org.  For more info on Linux MM,
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
@ 2017-01-11  6:18   ` Hillf Danton
  2017-01-13  9:18   ` Michal Hocko
  2017-01-14 16:12   ` Johannes Weiner
  2 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-11  6:18 UTC (permalink / raw)
  To: 'Michal Hocko', linux-mm
  Cc: 'Johannes Weiner', 'Mel Gorman',
	'Minchan Kim', 'Andrew Morton',
	'Michal Hocko'



On Tuesday, January 10, 2017 8:56 PM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Changes since v1
> - s@lruvec_lru_size_zone_idx@lruvec_lru_size_eligibe_zones@
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 


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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low
  2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
  2017-01-10 23:56   ` Minchan Kim
@ 2017-01-11  6:22   ` Hillf Danton
  2017-01-14 16:16   ` Johannes Weiner
  2 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-11  6:22 UTC (permalink / raw)
  To: 'Michal Hocko', linux-mm
  Cc: 'Johannes Weiner', 'Mel Gorman',
	'Minchan Kim', 'Andrew Morton',
	'Michal Hocko'


On Tuesday, January 10, 2017 8:56 PM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> inactive_list_is_low is duplicating logic implemented by
> lruvec_lru_size_eligibe_zones. Let's use the dedicated function to get
> the number of eligible pages on the lru list and ask use lruvec_lru_size
> to get the total LRU lize only when the tracing is really requested. We
> are still iterating over all LRUs two times in that case but a)
> inactive_list_is_low is not a hot path and b) this can be addressed at
> the tracing layer and only evaluate arguments only when the tracing is
> enabled in future if that ever matters.
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>


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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
  2017-01-11  6:18   ` Hillf Danton
@ 2017-01-13  9:18   ` Michal Hocko
  2017-01-17  6:47     ` Minchan Kim
  2017-01-14 16:12   ` Johannes Weiner
  2 siblings, 1 reply; 36+ messages in thread
From: Michal Hocko @ 2017-01-13  9:18 UTC (permalink / raw)
  To: Minchan Kim; +Cc: Johannes Weiner, Mel Gorman, linux-mm, Andrew Morton

On Tue 10-01-17 13:55:51, Michal Hocko wrote:
[...]
> @@ -2280,7 +2306,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
>  			unsigned long size;
>  			unsigned long scan;
>  
> -			size = lruvec_lru_size(lruvec, lru);
> +			size = lruvec_lru_size_eligibe_zones(lruvec, lru, sc->reclaim_idx);
>  			scan = size >> sc->priority;
>  
>  			if (!scan && pass && force_scan)

I have just come across inactive_reclaimable_pages and it seems it is
unnecessary after this, right Minchan?
-- 
Michal Hocko
SUSE Labs

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
  2017-01-11  6:18   ` Hillf Danton
  2017-01-13  9:18   ` Michal Hocko
@ 2017-01-14 16:12   ` Johannes Weiner
  2017-01-16  9:29     ` Michal Hocko
  2 siblings, 1 reply; 36+ messages in thread
From: Johannes Weiner @ 2017-01-14 16:12 UTC (permalink / raw)
  To: Michal Hocko
  Cc: linux-mm, Mel Gorman, Minchan Kim, Andrew Morton, Michal Hocko

On Tue, Jan 10, 2017 at 01:55:51PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.

The amount of retrofitting zones back into reclaim is disappointing :/

>  /*
> + * Return the number of pages on the given lru which are eligible for the
> + * given zone_idx
> + */
> +static unsigned long lruvec_lru_size_eligibe_zones(struct lruvec *lruvec,
> +		enum lru_list lru, int zone_idx)
> +{
> +	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> +	unsigned long lru_size;
> +	int zid;
> +
> +	lru_size = lruvec_lru_size(lruvec, lru);
> +	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
> +		struct zone *zone = &pgdat->node_zones[zid];
> +		unsigned long size;
> +
> +		if (!managed_zone(zone))
> +			continue;
> +
> +		size = lruvec_zone_lru_size(lruvec, lru, zid);
> +		lru_size -= min(size, lru_size);
> +	}
> +
> +	return lru_size;

The only other use of lruvec_lru_size() is also in get_scan_count(),
where it decays the LRU pressure balancing ratios. That caller wants
to operate on the entire lruvec.

Can you instead add the filtering logic to lruvec_lru_size() directly,
and pass MAX_NR_ZONES when operating on the entire lruvec? That would
make the code quite a bit clearer than having 3 different lruvec size
querying functions.

--
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low
  2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
  2017-01-10 23:56   ` Minchan Kim
  2017-01-11  6:22   ` Hillf Danton
@ 2017-01-14 16:16   ` Johannes Weiner
  2 siblings, 0 replies; 36+ messages in thread
From: Johannes Weiner @ 2017-01-14 16:16 UTC (permalink / raw)
  To: Michal Hocko
  Cc: linux-mm, Mel Gorman, Minchan Kim, Andrew Morton, Michal Hocko

On Tue, Jan 10, 2017 at 01:55:52PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> inactive_list_is_low is duplicating logic implemented by
> lruvec_lru_size_eligibe_zones. Let's use the dedicated function to get
> the number of eligible pages on the lru list and ask use lruvec_lru_size
> to get the total LRU lize only when the tracing is really requested. We
> are still iterating over all LRUs two times in that case but a)
> inactive_list_is_low is not a hot path and b) this can be addressed at
> the tracing layer and only evaluate arguments only when the tracing is
> enabled in future if that ever matters.

lruvec_zone_lru_size() is no longer needed after this. Again, it would
be better to consolidate everything into one lruvec_lru_size() that
takes a reclaim index. Trivial to rebase on top of that, though, so:

> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

Thanks

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-14 16:12   ` Johannes Weiner
@ 2017-01-16  9:29     ` Michal Hocko
  2017-01-16 16:01       ` Johannes Weiner
  0 siblings, 1 reply; 36+ messages in thread
From: Michal Hocko @ 2017-01-16  9:29 UTC (permalink / raw)
  To: Johannes Weiner; +Cc: linux-mm, Mel Gorman, Minchan Kim, Andrew Morton

On Sat 14-01-17 11:12:36, Johannes Weiner wrote:
> On Tue, Jan 10, 2017 at 01:55:51PM +0100, Michal Hocko wrote:
> > From: Michal Hocko <mhocko@suse.com>
> > 
> > get_scan_count considers the whole node LRU size when
> > - doing SCAN_FILE due to many page cache inactive pages
> > - calculating the number of pages to scan
> > 
> > in both cases this might lead to unexpected behavior especially on 32b
> > systems where we can expect lowmem memory pressure very often.
> 
> The amount of retrofitting zones back into reclaim is disappointing :/

Agreed
 
> >  /*
> > + * Return the number of pages on the given lru which are eligible for the
> > + * given zone_idx
> > + */
> > +static unsigned long lruvec_lru_size_eligibe_zones(struct lruvec *lruvec,
> > +		enum lru_list lru, int zone_idx)
> > +{
> > +	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> > +	unsigned long lru_size;
> > +	int zid;
> > +
> > +	lru_size = lruvec_lru_size(lruvec, lru);
> > +	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
> > +		struct zone *zone = &pgdat->node_zones[zid];
> > +		unsigned long size;
> > +
> > +		if (!managed_zone(zone))
> > +			continue;
> > +
> > +		size = lruvec_zone_lru_size(lruvec, lru, zid);
> > +		lru_size -= min(size, lru_size);
> > +	}
> > +
> > +	return lru_size;
> 
> The only other use of lruvec_lru_size() is also in get_scan_count(),
> where it decays the LRU pressure balancing ratios. That caller wants
> to operate on the entire lruvec.
> 
> Can you instead add the filtering logic to lruvec_lru_size() directly,
> and pass MAX_NR_ZONES when operating on the entire lruvec? That would
> make the code quite a bit clearer than having 3 different lruvec size
> querying functions.

OK, fair point. What about this?
---

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-16  9:29     ` Michal Hocko
@ 2017-01-16 16:01       ` Johannes Weiner
  2017-01-16 19:33           ` Michal Hocko
  0 siblings, 1 reply; 36+ messages in thread
From: Johannes Weiner @ 2017-01-16 16:01 UTC (permalink / raw)
  To: Michal Hocko; +Cc: linux-mm, Mel Gorman, Minchan Kim, Andrew Morton

On Mon, Jan 16, 2017 at 10:29:56AM +0100, Michal Hocko wrote:
> From 39824aac7504b38f943a80b7d98ec4e87a5607a7 Mon Sep 17 00:00:00 2001
> From: Michal Hocko <mhocko@suse.com>
> Date: Tue, 27 Dec 2016 16:28:44 +0100
> Subject: [PATCH] mm, vmscan: consider eligible zones in get_scan_count
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by making lruvec_lru_size zone aware. zone_idx will tell the
> the maximum eligible zone.
> 
> Changes since v2
> - move the zone filtering logic to lruvec_lru_size so that we do not
>   have too many lruvec_lru_size* functions - Johannes
> 
> Changes since v1
> - s@lruvec_lru_size_zone_idx@lruvec_lru_size_eligibe_zones@
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Thanks, that looks better IMO. Two tiny things:

> @@ -234,22 +234,44 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
>  		pgdat_reclaimable_pages(pgdat) * 6;
>  }
>  
> -unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
> +static unsigned long lruvec_zone_lru_size(struct lruvec *lruvec,
> +		enum lru_list lru, int zone_idx)
>  {
>  	if (!mem_cgroup_disabled())
> -		return mem_cgroup_get_lru_size(lruvec, lru);
> +		return mem_cgroup_get_zone_lru_size(lruvec, lru, zone_idx);
>  
> -	return node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
> +	return zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zone_idx],
> +			       NR_ZONE_LRU_BASE + lru);
>  }
>  
> -unsigned long lruvec_zone_lru_size(struct lruvec *lruvec, enum lru_list lru,
> -				   int zone_idx)
> +/** lruvec_lru_size -  Returns the number of pages on the given LRU list.
> + * @lruvec: lru vector
> + * @lru: lru to use
> + * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list)
> + */
> +unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
>  {
> +	unsigned long lru_size;
> +	int zid;
> +
>  	if (!mem_cgroup_disabled())
> -		return mem_cgroup_get_zone_lru_size(lruvec, lru, zone_idx);
> +		lru_size = mem_cgroup_get_lru_size(lruvec, lru);
> +	else
> +		lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
> +
> +	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
> +		struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
> +		unsigned long size;
> +
> +		if (!managed_zone(zone))
> +			continue;
> +
> +		size = lruvec_zone_lru_size(lruvec, lru, zid);
> +		lru_size -= min(size, lru_size);

Fold lruvec_zone_lru_size() in here? Its body goes well with how we
get lru_size at the start of the function, no need to maintain that
abstraction.

> @@ -2064,8 +2086,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
>  	if (!file && !total_swap_pages)
>  		return false;
>  
> -	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
> -	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
> +	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE, MAX_NR_ZONES);
> +	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE, MAX_NR_ZONES);
>  
>  	/*
>  	 * For zone-constrained allocations, it is necessary to check if

It might be a better patch order to do the refactoring of the zone
filtering from inactive_list_is_low() to lruvec_lru_size() in 1/2,
without change of behavior; then update the other callers in 2/2.

Hm?

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* [PATCH 1/3] mm, vmscan: cleanup lru size claculations
  2017-01-16 16:01       ` Johannes Weiner
@ 2017-01-16 19:33           ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

lruvec_lru_size returns the full size of the LRU list while we sometimes
need a value reduced only to eligible zones (e.g. for lowmem requests).
inactive_list_is_low is one such user. Later patches will add more of
them. Add a new parameter to lruvec_lru_size and allow it filter out
zones which are not eligible for the given context.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/mmzone.h |  2 +-
 mm/vmscan.c            | 88 ++++++++++++++++++++++++--------------------------
 mm/workingset.c        |  2 +-
 3 files changed, 45 insertions(+), 47 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d1d440cff60e..91f69aa0d581 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -780,7 +780,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
 #endif
 }
 
-extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
+extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
 
 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 void memory_present(int nid, unsigned long start, unsigned long end);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cf940af609fd..1cb0ebdef305 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -234,22 +234,38 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
 		pgdat_reclaimable_pages(pgdat) * 6;
 }
 
-unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
+/** lruvec_lru_size -  Returns the number of pages on the given LRU list.
+ * @lruvec: lru vector
+ * @lru: lru to use
+ * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list)
+ */
+unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
 {
+	unsigned long lru_size;
+	int zid;
+
 	if (!mem_cgroup_disabled())
-		return mem_cgroup_get_lru_size(lruvec, lru);
+		lru_size = mem_cgroup_get_lru_size(lruvec, lru);
+	else
+		lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
 
-	return node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
-}
+	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
+		struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
+		unsigned long size;
 
-unsigned long lruvec_zone_lru_size(struct lruvec *lruvec, enum lru_list lru,
-				   int zone_idx)
-{
-	if (!mem_cgroup_disabled())
-		return mem_cgroup_get_zone_lru_size(lruvec, lru, zone_idx);
+		if (!managed_zone(zone))
+			continue;
+
+		if (!mem_cgroup_disabled())
+			size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
+		else
+			size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
+				       NR_ZONE_LRU_BASE + lru);
+		lru_size -= min(size, lru_size);
+	}
+
+	return lru_size;
 
-	return zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zone_idx],
-			       NR_ZONE_LRU_BASE + lru);
 }
 
 /*
@@ -2051,11 +2067,10 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 						struct scan_control *sc, bool trace)
 {
 	unsigned long inactive_ratio;
-	unsigned long total_inactive, inactive;
-	unsigned long total_active, active;
+	unsigned long inactive, active;
+	enum lru_list inactive_lru = file * LRU_FILE;
+	enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE;
 	unsigned long gb;
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-	int zid;
 
 	/*
 	 * If we don't have swap space, anonymous page deactivation
@@ -2064,27 +2079,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 	if (!file && !total_swap_pages)
 		return false;
 
-	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
-	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
-
-	/*
-	 * For zone-constrained allocations, it is necessary to check if
-	 * deactivations are required for lowmem to be reclaimed. This
-	 * calculates the inactive/active pages available in eligible zones.
-	 */
-	for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {
-		struct zone *zone = &pgdat->node_zones[zid];
-		unsigned long inactive_zone, active_zone;
-
-		if (!managed_zone(zone))
-			continue;
-
-		inactive_zone = lruvec_zone_lru_size(lruvec, file * LRU_FILE, zid);
-		active_zone = lruvec_zone_lru_size(lruvec, (file * LRU_FILE) + LRU_ACTIVE, zid);
-
-		inactive -= min(inactive, inactive_zone);
-		active -= min(active, active_zone);
-	}
+	inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx);
+	active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx);
 
 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
 	if (gb)
@@ -2093,10 +2089,12 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 		inactive_ratio = 1;
 
 	if (trace)
-		trace_mm_vmscan_inactive_list_is_low(pgdat->node_id,
+		trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id,
 				sc->reclaim_idx,
-				total_inactive, inactive,
-				total_active, active, inactive_ratio, file);
+				lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive,
+				lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active,
+				inactive_ratio, file);
+
 	return inactive * inactive_ratio < active;
 }
 
@@ -2236,7 +2234,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2262,10 +2260,10 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * anon in [0], file in [1]
 	 */
 
-	anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON) +
-		lruvec_lru_size(lruvec, LRU_INACTIVE_ANON);
-	file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE) +
-		lruvec_lru_size(lruvec, LRU_INACTIVE_FILE);
+	anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) +
+		lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES);
+	file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) +
+		lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES);
 
 	spin_lock_irq(&pgdat->lru_lock);
 	if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
@@ -2303,7 +2301,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru);
+			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
diff --git a/mm/workingset.c b/mm/workingset.c
index abb58ffa3c64..a67f5796b995 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -267,7 +267,7 @@ bool workingset_refault(void *shadow)
 	}
 	lruvec = mem_cgroup_lruvec(pgdat, memcg);
 	refault = atomic_long_read(&lruvec->inactive_age);
-	active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE);
+	active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES);
 	rcu_read_unlock();
 
 	/*
-- 
2.11.0

^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 1/3] mm, vmscan: cleanup lru size claculations
@ 2017-01-16 19:33           ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

lruvec_lru_size returns the full size of the LRU list while we sometimes
need a value reduced only to eligible zones (e.g. for lowmem requests).
inactive_list_is_low is one such user. Later patches will add more of
them. Add a new parameter to lruvec_lru_size and allow it filter out
zones which are not eligible for the given context.

Acked-by: Johannes Weiner <hannes@cmpxchg.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 include/linux/mmzone.h |  2 +-
 mm/vmscan.c            | 88 ++++++++++++++++++++++++--------------------------
 mm/workingset.c        |  2 +-
 3 files changed, 45 insertions(+), 47 deletions(-)

diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
index d1d440cff60e..91f69aa0d581 100644
--- a/include/linux/mmzone.h
+++ b/include/linux/mmzone.h
@@ -780,7 +780,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
 #endif
 }
 
-extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
+extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
 
 #ifdef CONFIG_HAVE_MEMORY_PRESENT
 void memory_present(int nid, unsigned long start, unsigned long end);
diff --git a/mm/vmscan.c b/mm/vmscan.c
index cf940af609fd..1cb0ebdef305 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -234,22 +234,38 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
 		pgdat_reclaimable_pages(pgdat) * 6;
 }
 
-unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
+/** lruvec_lru_size -  Returns the number of pages on the given LRU list.
+ * @lruvec: lru vector
+ * @lru: lru to use
+ * @zone_idx: zones to consider (use MAX_NR_ZONES for the whole LRU list)
+ */
+unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx)
 {
+	unsigned long lru_size;
+	int zid;
+
 	if (!mem_cgroup_disabled())
-		return mem_cgroup_get_lru_size(lruvec, lru);
+		lru_size = mem_cgroup_get_lru_size(lruvec, lru);
+	else
+		lru_size = node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
 
-	return node_page_state(lruvec_pgdat(lruvec), NR_LRU_BASE + lru);
-}
+	for (zid = zone_idx + 1; zid < MAX_NR_ZONES; zid++) {
+		struct zone *zone = &lruvec_pgdat(lruvec)->node_zones[zid];
+		unsigned long size;
 
-unsigned long lruvec_zone_lru_size(struct lruvec *lruvec, enum lru_list lru,
-				   int zone_idx)
-{
-	if (!mem_cgroup_disabled())
-		return mem_cgroup_get_zone_lru_size(lruvec, lru, zone_idx);
+		if (!managed_zone(zone))
+			continue;
+
+		if (!mem_cgroup_disabled())
+			size = mem_cgroup_get_zone_lru_size(lruvec, lru, zid);
+		else
+			size = zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zid],
+				       NR_ZONE_LRU_BASE + lru);
+		lru_size -= min(size, lru_size);
+	}
+
+	return lru_size;
 
-	return zone_page_state(&lruvec_pgdat(lruvec)->node_zones[zone_idx],
-			       NR_ZONE_LRU_BASE + lru);
 }
 
 /*
@@ -2051,11 +2067,10 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 						struct scan_control *sc, bool trace)
 {
 	unsigned long inactive_ratio;
-	unsigned long total_inactive, inactive;
-	unsigned long total_active, active;
+	unsigned long inactive, active;
+	enum lru_list inactive_lru = file * LRU_FILE;
+	enum lru_list active_lru = file * LRU_FILE + LRU_ACTIVE;
 	unsigned long gb;
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-	int zid;
 
 	/*
 	 * If we don't have swap space, anonymous page deactivation
@@ -2064,27 +2079,8 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 	if (!file && !total_swap_pages)
 		return false;
 
-	total_inactive = inactive = lruvec_lru_size(lruvec, file * LRU_FILE);
-	total_active = active = lruvec_lru_size(lruvec, file * LRU_FILE + LRU_ACTIVE);
-
-	/*
-	 * For zone-constrained allocations, it is necessary to check if
-	 * deactivations are required for lowmem to be reclaimed. This
-	 * calculates the inactive/active pages available in eligible zones.
-	 */
-	for (zid = sc->reclaim_idx + 1; zid < MAX_NR_ZONES; zid++) {
-		struct zone *zone = &pgdat->node_zones[zid];
-		unsigned long inactive_zone, active_zone;
-
-		if (!managed_zone(zone))
-			continue;
-
-		inactive_zone = lruvec_zone_lru_size(lruvec, file * LRU_FILE, zid);
-		active_zone = lruvec_zone_lru_size(lruvec, (file * LRU_FILE) + LRU_ACTIVE, zid);
-
-		inactive -= min(inactive, inactive_zone);
-		active -= min(active, active_zone);
-	}
+	inactive = lruvec_lru_size(lruvec, inactive_lru, sc->reclaim_idx);
+	active = lruvec_lru_size(lruvec, active_lru, sc->reclaim_idx);
 
 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
 	if (gb)
@@ -2093,10 +2089,12 @@ static bool inactive_list_is_low(struct lruvec *lruvec, bool file,
 		inactive_ratio = 1;
 
 	if (trace)
-		trace_mm_vmscan_inactive_list_is_low(pgdat->node_id,
+		trace_mm_vmscan_inactive_list_is_low(lruvec_pgdat(lruvec)->node_id,
 				sc->reclaim_idx,
-				total_inactive, inactive,
-				total_active, active, inactive_ratio, file);
+				lruvec_lru_size(lruvec, inactive_lru, MAX_NR_ZONES), inactive,
+				lruvec_lru_size(lruvec, active_lru, MAX_NR_ZONES), active,
+				inactive_ratio, file);
+
 	return inactive * inactive_ratio < active;
 }
 
@@ -2236,7 +2234,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2262,10 +2260,10 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * anon in [0], file in [1]
 	 */
 
-	anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON) +
-		lruvec_lru_size(lruvec, LRU_INACTIVE_ANON);
-	file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE) +
-		lruvec_lru_size(lruvec, LRU_INACTIVE_FILE);
+	anon  = lruvec_lru_size(lruvec, LRU_ACTIVE_ANON, MAX_NR_ZONES) +
+		lruvec_lru_size(lruvec, LRU_INACTIVE_ANON, MAX_NR_ZONES);
+	file  = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES) +
+		lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES);
 
 	spin_lock_irq(&pgdat->lru_lock);
 	if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
@@ -2303,7 +2301,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru);
+			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
diff --git a/mm/workingset.c b/mm/workingset.c
index abb58ffa3c64..a67f5796b995 100644
--- a/mm/workingset.c
+++ b/mm/workingset.c
@@ -267,7 +267,7 @@ bool workingset_refault(void *shadow)
 	}
 	lruvec = mem_cgroup_lruvec(pgdat, memcg);
 	refault = atomic_long_read(&lruvec->inactive_age);
-	active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE);
+	active_file = lruvec_lru_size(lruvec, LRU_ACTIVE_FILE, MAX_NR_ZONES);
 	rcu_read_unlock();
 
 	/*
-- 
2.11.0

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^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-16 19:33           ` Michal Hocko
@ 2017-01-16 19:33             ` Michal Hocko
  -1 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

get_scan_count considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan

in both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.

A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.

The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
at maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.

Fix this by filtering out all the ineligible zones when calculating the
lru size for both paths and consider only sc->reclaim_idx zones.

Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1cb0ebdef305..a88e222784ea 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2234,7 +2234,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2301,7 +2301,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
+			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
-- 
2.11.0

^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-01-16 19:33             ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

get_scan_count considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan

in both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.

A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.

The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
at maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.

Fix this by filtering out all the ineligible zones when calculating the
lru size for both paths and consider only sc->reclaim_idx zones.

Acked-by: Minchan Kim <minchan@kernel.org>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 1cb0ebdef305..a88e222784ea 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2234,7 +2234,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2301,7 +2301,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
+			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
-- 
2.11.0

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^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
  2017-01-16 19:33           ` Michal Hocko
@ 2017-01-16 19:33             ` Michal Hocko
  -1 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
inactive_reclaimable_pages shouldn't be needed anymore since that
get_scan_count is aware of the eligble zones ("mm, vmscan: consider
eligible zones in get_scan_count").

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a88e222784ea..486ba6d7dc4c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1700,30 +1700,6 @@ static int current_may_throttle(void)
 		bdi_write_congested(current->backing_dev_info);
 }
 
-static bool inactive_reclaimable_pages(struct lruvec *lruvec,
-				struct scan_control *sc, enum lru_list lru)
-{
-	int zid;
-	struct zone *zone;
-	int file = is_file_lru(lru);
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-
-	if (!global_reclaim(sc))
-		return true;
-
-	for (zid = sc->reclaim_idx; zid >= 0; zid--) {
-		zone = &pgdat->node_zones[zid];
-		if (!managed_zone(zone))
-			continue;
-
-		if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
-				LRU_FILE * file) >= SWAP_CLUSTER_MAX)
-			return true;
-	}
-
-	return false;
-}
-
 /*
  * shrink_inactive_list() is a helper for shrink_node().  It returns the number
  * of reclaimed pages
@@ -1742,9 +1718,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 
-	if (!inactive_reclaimable_pages(lruvec, sc, lru))
-		return 0;
-
 	while (unlikely(too_many_isolated(pgdat, file, sc))) {
 		congestion_wait(BLK_RW_ASYNC, HZ/10);
 
-- 
2.11.0

^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
@ 2017-01-16 19:33             ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-16 19:33 UTC (permalink / raw)
  To: Johannes Weiner
  Cc: Minchan Kim, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
inactive_reclaimable_pages shouldn't be needed anymore since that
get_scan_count is aware of the eligble zones ("mm, vmscan: consider
eligible zones in get_scan_count").

Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 27 ---------------------------
 1 file changed, 27 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index a88e222784ea..486ba6d7dc4c 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1700,30 +1700,6 @@ static int current_may_throttle(void)
 		bdi_write_congested(current->backing_dev_info);
 }
 
-static bool inactive_reclaimable_pages(struct lruvec *lruvec,
-				struct scan_control *sc, enum lru_list lru)
-{
-	int zid;
-	struct zone *zone;
-	int file = is_file_lru(lru);
-	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
-
-	if (!global_reclaim(sc))
-		return true;
-
-	for (zid = sc->reclaim_idx; zid >= 0; zid--) {
-		zone = &pgdat->node_zones[zid];
-		if (!managed_zone(zone))
-			continue;
-
-		if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
-				LRU_FILE * file) >= SWAP_CLUSTER_MAX)
-			return true;
-	}
-
-	return false;
-}
-
 /*
  * shrink_inactive_list() is a helper for shrink_node().  It returns the number
  * of reclaimed pages
@@ -1742,9 +1718,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
 	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
 	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
 
-	if (!inactive_reclaimable_pages(lruvec, sc, lru))
-		return 0;
-
 	while (unlikely(too_many_isolated(pgdat, file, sc))) {
 		congestion_wait(BLK_RW_ASYNC, HZ/10);
 
-- 
2.11.0

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply related	[flat|nested] 36+ messages in thread
* Re: [PATCH 1/3] mm, vmscan: cleanup lru size claculations
  2017-01-16 19:33           ` Michal Hocko
@ 2017-01-17  3:40             ` Hillf Danton
  -1 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:40 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'

On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> lruvec_lru_size returns the full size of the LRU list while we sometimes
> need a value reduced only to eligible zones (e.g. for lowmem requests).
> inactive_list_is_low is one such user. Later patches will add more of
> them. Add a new parameter to lruvec_lru_size and allow it filter out
> zones which are not eligible for the given context.
> 
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 1/3] mm, vmscan: cleanup lru size claculations
@ 2017-01-17  3:40             ` Hillf Danton
  0 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:40 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'

On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> lruvec_lru_size returns the full size of the LRU list while we sometimes
> need a value reduced only to eligible zones (e.g. for lowmem requests).
> inactive_list_is_low is one such user. Later patches will add more of
> them. Add a new parameter to lruvec_lru_size and allow it filter out
> zones which are not eligible for the given context.
> 
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 


--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-16 19:33             ` Michal Hocko
@ 2017-01-17  3:42               ` Hillf Danton
  -1 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:42 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'


On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-01-17  3:42               ` Hillf Danton
  0 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:42 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'


On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 


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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
  2017-01-16 19:33             ` Michal Hocko
@ 2017-01-17  3:58               ` Hillf Danton
  -1 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:58 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'


On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
> inactive_reclaimable_pages shouldn't be needed anymore since that
> get_scan_count is aware of the eligble zones ("mm, vmscan: consider
> eligible zones in get_scan_count").
> 
Looks radical ;)

> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 

>  mm/vmscan.c | 27 ---------------------------
>  1 file changed, 27 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a88e222784ea..486ba6d7dc4c 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1700,30 +1700,6 @@ static int current_may_throttle(void)
>  		bdi_write_congested(current->backing_dev_info);
>  }
> 
> -static bool inactive_reclaimable_pages(struct lruvec *lruvec,
> -				struct scan_control *sc, enum lru_list lru)
> -{
> -	int zid;
> -	struct zone *zone;
> -	int file = is_file_lru(lru);
> -	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> -
> -	if (!global_reclaim(sc))
> -		return true;
> -
> -	for (zid = sc->reclaim_idx; zid >= 0; zid--) {
> -		zone = &pgdat->node_zones[zid];
> -		if (!managed_zone(zone))
> -			continue;
> -
> -		if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
> -				LRU_FILE * file) >= SWAP_CLUSTER_MAX)
> -			return true;
> -	}
> -
> -	return false;
> -}
> -
>  /*
>   * shrink_inactive_list() is a helper for shrink_node().  It returns the number
>   * of reclaimed pages
> @@ -1742,9 +1718,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
>  	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
> 
> -	if (!inactive_reclaimable_pages(lruvec, sc, lru))
> -		return 0;
> -
>  	while (unlikely(too_many_isolated(pgdat, file, sc))) {
>  		congestion_wait(BLK_RW_ASYNC, HZ/10);
> 
> --
> 2.11.0

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
@ 2017-01-17  3:58               ` Hillf Danton
  0 siblings, 0 replies; 36+ messages in thread
From: Hillf Danton @ 2017-01-17  3:58 UTC (permalink / raw)
  To: 'Michal Hocko', 'Johannes Weiner'
  Cc: 'Minchan Kim', 'Mel Gorman',
	linux-mm, 'LKML', 'Michal Hocko'


On Tuesday, January 17, 2017 3:33 AM Michal Hocko wrote: 
> 
> From: Michal Hocko <mhocko@suse.com>
> 
> This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
> inactive_reclaimable_pages shouldn't be needed anymore since that
> get_scan_count is aware of the eligble zones ("mm, vmscan: consider
> eligible zones in get_scan_count").
> 
Looks radical ;)

> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com> 

>  mm/vmscan.c | 27 ---------------------------
>  1 file changed, 27 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index a88e222784ea..486ba6d7dc4c 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1700,30 +1700,6 @@ static int current_may_throttle(void)
>  		bdi_write_congested(current->backing_dev_info);
>  }
> 
> -static bool inactive_reclaimable_pages(struct lruvec *lruvec,
> -				struct scan_control *sc, enum lru_list lru)
> -{
> -	int zid;
> -	struct zone *zone;
> -	int file = is_file_lru(lru);
> -	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
> -
> -	if (!global_reclaim(sc))
> -		return true;
> -
> -	for (zid = sc->reclaim_idx; zid >= 0; zid--) {
> -		zone = &pgdat->node_zones[zid];
> -		if (!managed_zone(zone))
> -			continue;
> -
> -		if (zone_page_state_snapshot(zone, NR_ZONE_LRU_BASE +
> -				LRU_FILE * file) >= SWAP_CLUSTER_MAX)
> -			return true;
> -	}
> -
> -	return false;
> -}
> -
>  /*
>   * shrink_inactive_list() is a helper for shrink_node().  It returns the number
>   * of reclaimed pages
> @@ -1742,9 +1718,6 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
>  	struct pglist_data *pgdat = lruvec_pgdat(lruvec);
>  	struct zone_reclaim_stat *reclaim_stat = &lruvec->reclaim_stat;
> 
> -	if (!inactive_reclaimable_pages(lruvec, sc, lru))
> -		return 0;
> -
>  	while (unlikely(too_many_isolated(pgdat, file, sc))) {
>  		congestion_wait(BLK_RW_ASYNC, HZ/10);
> 
> --
> 2.11.0

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-13  9:18   ` Michal Hocko
@ 2017-01-17  6:47     ` Minchan Kim
  0 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-17  6:47 UTC (permalink / raw)
  To: Michal Hocko; +Cc: Johannes Weiner, Mel Gorman, linux-mm, Andrew Morton

On Fri, Jan 13, 2017 at 10:18:05AM +0100, Michal Hocko wrote:
> On Tue 10-01-17 13:55:51, Michal Hocko wrote:
> [...]
> > @@ -2280,7 +2306,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
> >  			unsigned long size;
> >  			unsigned long scan;
> >  
> > -			size = lruvec_lru_size(lruvec, lru);
> > +			size = lruvec_lru_size_eligibe_zones(lruvec, lru, sc->reclaim_idx);
> >  			scan = size >> sc->priority;
> >  
> >  			if (!scan && pass && force_scan)
> 
> I have just come across inactive_reclaimable_pages and it seems it is
> unnecessary after this, right Minchan?

Good catch.

At that time, I also wanted to change get_scan_count to fix the problem but
be lack of report and other guys didn't want it. :-(

I'm happy to see it now.
Thanks.

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 1/3] mm, vmscan: cleanup lru size claculations
  2017-01-16 19:33           ` Michal Hocko
@ 2017-01-17  6:58             ` Minchan Kim
  -1 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-17  6:58 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

On Mon, Jan 16, 2017 at 08:33:15PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> lruvec_lru_size returns the full size of the LRU list while we sometimes
> need a value reduced only to eligible zones (e.g. for lowmem requests).
> inactive_list_is_low is one such user. Later patches will add more of
> them. Add a new parameter to lruvec_lru_size and allow it filter out
> zones which are not eligible for the given context.
> 
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  include/linux/mmzone.h |  2 +-
>  mm/vmscan.c            | 88 ++++++++++++++++++++++++--------------------------
>  mm/workingset.c        |  2 +-
>  3 files changed, 45 insertions(+), 47 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index d1d440cff60e..91f69aa0d581 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -780,7 +780,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
>  #endif
>  }
>  
> -extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
> +extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
>  
>  #ifdef CONFIG_HAVE_MEMORY_PRESENT
>  void memory_present(int nid, unsigned long start, unsigned long end);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index cf940af609fd..1cb0ebdef305 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -234,22 +234,38 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
>  		pgdat_reclaimable_pages(pgdat) * 6;
>  }
>  
> -unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
> +/** lruvec_lru_size -  Returns the number of pages on the given LRU list.

minor:

/*
 * lruvec_lru_size

I don't have any preferance but just found.

Otherwise,
Acked-by: Minchan Kim <minchan@kernel.org>

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 1/3] mm, vmscan: cleanup lru size claculations
@ 2017-01-17  6:58             ` Minchan Kim
  0 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-17  6:58 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

On Mon, Jan 16, 2017 at 08:33:15PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> lruvec_lru_size returns the full size of the LRU list while we sometimes
> need a value reduced only to eligible zones (e.g. for lowmem requests).
> inactive_list_is_low is one such user. Later patches will add more of
> them. Add a new parameter to lruvec_lru_size and allow it filter out
> zones which are not eligible for the given context.
> 
> Acked-by: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  include/linux/mmzone.h |  2 +-
>  mm/vmscan.c            | 88 ++++++++++++++++++++++++--------------------------
>  mm/workingset.c        |  2 +-
>  3 files changed, 45 insertions(+), 47 deletions(-)
> 
> diff --git a/include/linux/mmzone.h b/include/linux/mmzone.h
> index d1d440cff60e..91f69aa0d581 100644
> --- a/include/linux/mmzone.h
> +++ b/include/linux/mmzone.h
> @@ -780,7 +780,7 @@ static inline struct pglist_data *lruvec_pgdat(struct lruvec *lruvec)
>  #endif
>  }
>  
> -extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru);
> +extern unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru, int zone_idx);
>  
>  #ifdef CONFIG_HAVE_MEMORY_PRESENT
>  void memory_present(int nid, unsigned long start, unsigned long end);
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index cf940af609fd..1cb0ebdef305 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -234,22 +234,38 @@ bool pgdat_reclaimable(struct pglist_data *pgdat)
>  		pgdat_reclaimable_pages(pgdat) * 6;
>  }
>  
> -unsigned long lruvec_lru_size(struct lruvec *lruvec, enum lru_list lru)
> +/** lruvec_lru_size -  Returns the number of pages on the given LRU list.

minor:

/*
 * lruvec_lru_size

I don't have any preferance but just found.

Otherwise,
Acked-by: Minchan Kim <minchan@kernel.org>


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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
  2017-01-16 19:33             ` Michal Hocko
@ 2017-01-17  6:58               ` Minchan Kim
  -1 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-17  6:58 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

On Mon, Jan 16, 2017 at 08:33:17PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
> inactive_reclaimable_pages shouldn't be needed anymore since that
> get_scan_count is aware of the eligble zones ("mm, vmscan: consider
> eligible zones in get_scan_count").
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Minchan Kim <minchan@kernel.org>

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()"
@ 2017-01-17  6:58               ` Minchan Kim
  0 siblings, 0 replies; 36+ messages in thread
From: Minchan Kim @ 2017-01-17  6:58 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Hillf Danton, linux-mm, LKML, Michal Hocko

On Mon, Jan 16, 2017 at 08:33:17PM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> This reverts 91dcade47a3d0e7c31464ef05f56c08e92a0e9c2.
> inactive_reclaimable_pages shouldn't be needed anymore since that
> get_scan_count is aware of the eligble zones ("mm, vmscan: consider
> eligible zones in get_scan_count").
> 
> Signed-off-by: Michal Hocko <mhocko@suse.com>
Acked-by: Minchan Kim <minchan@kernel.org>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-02-06  8:10     ` Michal Hocko
@ 2017-02-06 23:40       ` Andrew Morton
  -1 siblings, 0 replies; 36+ messages in thread
From: Andrew Morton @ 2017-02-06 23:40 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Trevor Cordes

On Mon, 6 Feb 2017 09:10:07 +0100 Michal Hocko <mhocko@kernel.org> wrote:

> Hi Andrew,
> it turned out that this is not a theoretical issue after all. Trevor
> (added to the CC) was seeing pre-mature OOM killer triggering [1]
> bisected to b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a
> per-node basis").
> After some going back and forth it turned out that b4536f0c829c ("mm,
> memcg: fix the active list aging for lowmem requests when memcg is
> enabled") helped a lot but it wasn't sufficient on its own. We also
> need this patch to make the oom behavior stable again. So I suggest
> backporting this to stable as well. Could you update the changelog as
> follows?
> 
> The patch would need to be tweaked a bit to apply to 4.10 and older
> but I will do that as soon as it hits the Linus tree in the next merge
> window.
> 
> ...
>
> Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis")
> Cc: stable # 4.8+
> Tested-by: Trevor Cordes <trevor@tecnopolis.ca>

No probs.

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-02-06 23:40       ` Andrew Morton
  0 siblings, 0 replies; 36+ messages in thread
From: Andrew Morton @ 2017-02-06 23:40 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Trevor Cordes

On Mon, 6 Feb 2017 09:10:07 +0100 Michal Hocko <mhocko@kernel.org> wrote:

> Hi Andrew,
> it turned out that this is not a theoretical issue after all. Trevor
> (added to the CC) was seeing pre-mature OOM killer triggering [1]
> bisected to b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a
> per-node basis").
> After some going back and forth it turned out that b4536f0c829c ("mm,
> memcg: fix the active list aging for lowmem requests when memcg is
> enabled") helped a lot but it wasn't sufficient on its own. We also
> need this patch to make the oom behavior stable again. So I suggest
> backporting this to stable as well. Could you update the changelog as
> follows?
> 
> The patch would need to be tweaked a bit to apply to 4.10 and older
> but I will do that as soon as it hits the Linus tree in the next merge
> window.
> 
> ...
>
> Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis")
> Cc: stable # 4.8+
> Tested-by: Trevor Cordes <trevor@tecnopolis.ca>

No probs.

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
the body to majordomo@kvack.org.  For more info on Linux MM,
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-17 10:37   ` Michal Hocko
@ 2017-02-06  8:10     ` Michal Hocko
  -1 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-02-06  8:10 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Trevor Cordes

Hi Andrew,
it turned out that this is not a theoretical issue after all. Trevor
(added to the CC) was seeing pre-mature OOM killer triggering [1]
bisected to b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a
per-node basis").
After some going back and forth it turned out that b4536f0c829c ("mm,
memcg: fix the active list aging for lowmem requests when memcg is
enabled") helped a lot but it wasn't sufficient on its own. We also
need this patch to make the oom behavior stable again. So I suggest
backporting this to stable as well. Could you update the changelog as
follows?

The patch would need to be tweaked a bit to apply to 4.10 and older
but I will do that as soon as it hits the Linus tree in the next merge
window.

[1] http://lkml.kernel.org/r/20170111103243.GA27795@pog.tecnopolis.ca

On Tue 17-01-17 11:37:01, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 

Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis")
Cc: stable # 4.8+
Tested-by: Trevor Cordes <trevor@tecnopolis.ca>

> Acked-by: Minchan Kim <minchan@kernel.org>
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/vmscan.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index aed39dc272c0..ffac8fa7bdd8 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2235,7 +2235,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
>  	 * system is under heavy pressure.
>  	 */
>  	if (!inactive_list_is_low(lruvec, true, sc, false) &&
> -	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
> +	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
>  		scan_balance = SCAN_FILE;
>  		goto out;
>  	}
> @@ -2302,7 +2302,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
>  			unsigned long size;
>  			unsigned long scan;
>  
> -			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
> +			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
>  			scan = size >> sc->priority;
>  
>  			if (!scan && pass && force_scan)
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-02-06  8:10     ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-02-06  8:10 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Trevor Cordes

Hi Andrew,
it turned out that this is not a theoretical issue after all. Trevor
(added to the CC) was seeing pre-mature OOM killer triggering [1]
bisected to b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a
per-node basis").
After some going back and forth it turned out that b4536f0c829c ("mm,
memcg: fix the active list aging for lowmem requests when memcg is
enabled") helped a lot but it wasn't sufficient on its own. We also
need this patch to make the oom behavior stable again. So I suggest
backporting this to stable as well. Could you update the changelog as
follows?

The patch would need to be tweaked a bit to apply to 4.10 and older
but I will do that as soon as it hits the Linus tree in the next merge
window.

[1] http://lkml.kernel.org/r/20170111103243.GA27795@pog.tecnopolis.ca

On Tue 17-01-17 11:37:01, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 

Fixes: b2e18757f2c9 ("mm, vmscan: begin reclaiming pages on a per-node basis")
Cc: stable # 4.8+
Tested-by: Trevor Cordes <trevor@tecnopolis.ca>

> Acked-by: Minchan Kim <minchan@kernel.org>
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>
> ---
>  mm/vmscan.c | 4 ++--
>  1 file changed, 2 insertions(+), 2 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index aed39dc272c0..ffac8fa7bdd8 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -2235,7 +2235,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
>  	 * system is under heavy pressure.
>  	 */
>  	if (!inactive_list_is_low(lruvec, true, sc, false) &&
> -	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
> +	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
>  		scan_balance = SCAN_FILE;
>  		goto out;
>  	}
> @@ -2302,7 +2302,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
>  			unsigned long size;
>  			unsigned long scan;
>  
> -			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
> +			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
>  			scan = size >> sc->priority;
>  
>  			if (!scan && pass && force_scan)
> -- 
> 2.11.0
> 

-- 
Michal Hocko
SUSE Labs

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^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-17 10:37   ` Michal Hocko
@ 2017-01-18 16:46     ` Johannes Weiner
  -1 siblings, 0 replies; 36+ messages in thread
From: Johannes Weiner @ 2017-01-18 16:46 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Michal Hocko

On Tue, Jan 17, 2017 at 11:37:01AM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

^ permalink raw reply	[flat|nested] 36+ messages in thread
* Re: [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-01-18 16:46     ` Johannes Weiner
  0 siblings, 0 replies; 36+ messages in thread
From: Johannes Weiner @ 2017-01-18 16:46 UTC (permalink / raw)
  To: Michal Hocko
  Cc: Andrew Morton, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Michal Hocko

On Tue, Jan 17, 2017 at 11:37:01AM +0100, Michal Hocko wrote:
> From: Michal Hocko <mhocko@suse.com>
> 
> get_scan_count considers the whole node LRU size when
> - doing SCAN_FILE due to many page cache inactive pages
> - calculating the number of pages to scan
> 
> in both cases this might lead to unexpected behavior especially on 32b
> systems where we can expect lowmem memory pressure very often.
> 
> A large highmem zone can easily distort SCAN_FILE heuristic because
> there might be only few file pages from the eligible zones on the node
> lru and we would still enforce file lru scanning which can lead to
> trashing while we could still scan anonymous pages.
> 
> The later use of lruvec_lru_size can be problematic as well. Especially
> when there are not many pages from the eligible zones. We would have to
> skip over many pages to find anything to reclaim but shrink_node_memcg
> would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
> at maximum. Therefore we can end up going over a large LRU many times
> without actually having chance to reclaim much if anything at all. The
> closer we are out of memory on lowmem zone the worse the problem will
> be.
> 
> Fix this by filtering out all the ineligible zones when calculating the
> lru size for both paths and consider only sc->reclaim_idx zones.
> 
> Acked-by: Minchan Kim <minchan@kernel.org>
> Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
> Signed-off-by: Michal Hocko <mhocko@suse.com>

Acked-by: Johannes Weiner <hannes@cmpxchg.org>

--
To unsubscribe, send a message with 'unsubscribe linux-mm' in
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^ permalink raw reply	[flat|nested] 36+ messages in thread
* [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
  2017-01-17 10:36 [PATCH 0/3] follow up nodereclaim for 32b fix Michal Hocko
@ 2017-01-17 10:37   ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-17 10:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

get_scan_count considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan

in both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.

A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.

The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
at maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.

Fix this by filtering out all the ineligible zones when calculating the
lru size for both paths and consider only sc->reclaim_idx zones.

Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index aed39dc272c0..ffac8fa7bdd8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2235,7 +2235,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2302,7 +2302,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
+			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
-- 
2.11.0

^ permalink raw reply related	[flat|nested] 36+ messages in thread
* [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count
@ 2017-01-17 10:37   ` Michal Hocko
  0 siblings, 0 replies; 36+ messages in thread
From: Michal Hocko @ 2017-01-17 10:37 UTC (permalink / raw)
  To: Andrew Morton
  Cc: Johannes Weiner, Mel Gorman, Minchan Kim, Hillf Danton, linux-mm,
	LKML, Michal Hocko

From: Michal Hocko <mhocko@suse.com>

get_scan_count considers the whole node LRU size when
- doing SCAN_FILE due to many page cache inactive pages
- calculating the number of pages to scan

in both cases this might lead to unexpected behavior especially on 32b
systems where we can expect lowmem memory pressure very often.

A large highmem zone can easily distort SCAN_FILE heuristic because
there might be only few file pages from the eligible zones on the node
lru and we would still enforce file lru scanning which can lead to
trashing while we could still scan anonymous pages.

The later use of lruvec_lru_size can be problematic as well. Especially
when there are not many pages from the eligible zones. We would have to
skip over many pages to find anything to reclaim but shrink_node_memcg
would only reduce the remaining number to scan by SWAP_CLUSTER_MAX
at maximum. Therefore we can end up going over a large LRU many times
without actually having chance to reclaim much if anything at all. The
closer we are out of memory on lowmem zone the worse the problem will
be.

Fix this by filtering out all the ineligible zones when calculating the
lru size for both paths and consider only sc->reclaim_idx zones.

Acked-by: Minchan Kim <minchan@kernel.org>
Acked-by: Hillf Danton <hillf.zj@alibaba-inc.com>
Signed-off-by: Michal Hocko <mhocko@suse.com>
---
 mm/vmscan.c | 4 ++--
 1 file changed, 2 insertions(+), 2 deletions(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index aed39dc272c0..ffac8fa7bdd8 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2235,7 +2235,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 	 * system is under heavy pressure.
 	 */
 	if (!inactive_list_is_low(lruvec, true, sc, false) &&
-	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, MAX_NR_ZONES) >> sc->priority) {
+	    lruvec_lru_size(lruvec, LRU_INACTIVE_FILE, sc->reclaim_idx) >> sc->priority) {
 		scan_balance = SCAN_FILE;
 		goto out;
 	}
@@ -2302,7 +2302,7 @@ static void get_scan_count(struct lruvec *lruvec, struct mem_cgroup *memcg,
 			unsigned long size;
 			unsigned long scan;
 
-			size = lruvec_lru_size(lruvec, lru, MAX_NR_ZONES);
+			size = lruvec_lru_size(lruvec, lru, sc->reclaim_idx);
 			scan = size >> sc->priority;
 
 			if (!scan && pass && force_scan)
-- 
2.11.0

--
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^ permalink raw reply related	[flat|nested] 36+ messages in thread
end of thread, other threads:[~2017-02-06 23:40 UTC | newest]

Thread overview: 36+ messages (download: mbox.gz / follow: Atom feed)
-- links below jump to the message on this page --
2017-01-10 12:55 [RFC PATCH 0/2] follow up nodereclaim for 32b fix Michal Hocko
2017-01-10 12:55 ` [RFC PATCH 1/2] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
2017-01-11  6:18   ` Hillf Danton
2017-01-13  9:18   ` Michal Hocko
2017-01-17  6:47     ` Minchan Kim
2017-01-14 16:12   ` Johannes Weiner
2017-01-16  9:29     ` Michal Hocko
2017-01-16 16:01       ` Johannes Weiner
2017-01-16 19:33         ` [PATCH 1/3] mm, vmscan: cleanup lru size claculations Michal Hocko
2017-01-16 19:33           ` Michal Hocko
2017-01-16 19:33           ` [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
2017-01-16 19:33             ` Michal Hocko
2017-01-17  3:42             ` Hillf Danton
2017-01-17  3:42               ` Hillf Danton
2017-01-16 19:33           ` [PATCH 3/3] Reverted "mm: bail out in shrink_inactive_list()" Michal Hocko
2017-01-16 19:33             ` Michal Hocko
2017-01-17  3:58             ` Hillf Danton
2017-01-17  3:58               ` Hillf Danton
2017-01-17  6:58             ` Minchan Kim
2017-01-17  6:58               ` Minchan Kim
2017-01-17  3:40           ` [PATCH 1/3] mm, vmscan: cleanup lru size claculations Hillf Danton
2017-01-17  3:40             ` Hillf Danton
2017-01-17  6:58           ` Minchan Kim
2017-01-17  6:58             ` Minchan Kim
2017-01-10 12:55 ` [RFC PATCH 2/2] mm, vmscan: cleanup inactive_list_is_low Michal Hocko
2017-01-10 23:56   ` Minchan Kim
2017-01-11  6:22   ` Hillf Danton
2017-01-14 16:16   ` Johannes Weiner
2017-01-17 10:36 [PATCH 0/3] follow up nodereclaim for 32b fix Michal Hocko
2017-01-17 10:37 ` [PATCH 2/3] mm, vmscan: consider eligible zones in get_scan_count Michal Hocko
2017-01-17 10:37   ` Michal Hocko
2017-01-18 16:46   ` Johannes Weiner
2017-01-18 16:46     ` Johannes Weiner
2017-02-06  8:10   ` Michal Hocko
2017-02-06  8:10     ` Michal Hocko
2017-02-06 23:40     ` Andrew Morton
2017-02-06 23:40       ` Andrew Morton

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