Commit a458431e authored by Bartlomiej Zolnierkiewicz's avatar Bartlomiej Zolnierkiewicz Committed by Linus Torvalds
Browse files

mm: fix zone_watermark_ok_safe() accounting of isolated pages 



Commit 702d1a6e ("memory-hotplug: fix kswapd looping forever
problem") added an isolated pageblocks counter (nr_pageblock_isolate in
struct zone) and used it to adjust free pages counter in
zone_watermark_ok_safe() to prevent kswapd looping forever problem.

Then later, commit 2139cbe6 ("cma: fix counting of isolated pages")
fixed accounting of isolated pages in global free pages counter.  It
made the previous zone_watermark_ok_safe() fix unnecessary and
potentially harmful (cause now isolated pages may be accounted twice
making free pages counter incorrect).

This patch removes the special isolated pageblocks counter altogether
which fixes zone_watermark_ok_safe() free pages check.

Reported-by: default avatarTomasz Stanislawski <t.stanislaws@samsung.com>
Signed-off-by: default avatarBartlomiej Zolnierkiewicz <b.zolnierkie@samsung.com>
Signed-off-by: default avatarKyungmin Park <kyungmin.park@samsung.com>
Cc: Minchan Kim <minchan@kernel.org>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Cc: Aaditya Kumar <aaditya.kumar.30@gmail.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: Michal Hocko <mhocko@suse.cz>
Cc: Marek Szyprowski <m.szyprowski@samsung.com>
Cc: Michal Nazarewicz <mina86@mina86.com>
Cc: Hugh Dickins <hughd@google.com>
Signed-off-by: default avatarAndrew Morton <akpm@linux-foundation.org>
Signed-off-by: default avatarLinus Torvalds <torvalds@linux-foundation.org>
parent 358e419f

include/linux/mmzone.h

+0 −8
Original line number Diff line number Diff line
@@ -503,14 +503,6 @@ struct zone { 
	 * rarely used fields:

	 */

	const char		*name;

#ifdef CONFIG_MEMORY_ISOLATION

	/*

	 * the number of MIGRATE_ISOLATE *pageblock*.

	 * We need this for free page counting. Look at zone_watermark_ok_safe.

	 * It's protected by zone->lock

	 */

	int		nr_pageblock_isolate;

#endif

} ____cacheline_internodealigned_in_smp;



typedef enum {

mm/page_alloc.c

+0 −27
Original line number Diff line number Diff line
@@ -221,11 +221,6 @@ EXPORT_SYMBOL(nr_online_nodes); 


int page_group_by_mobility_disabled __read_mostly;



/*

 * NOTE:

 * Don't use set_pageblock_migratetype(page, MIGRATE_ISOLATE) directly.

 * Instead, use {un}set_pageblock_isolate.

 */

void set_pageblock_migratetype(struct page *page, int migratetype)

{
@@ -1655,20 +1650,6 @@ static bool __zone_watermark_ok(struct zone *z, int order, unsigned long mark, 
	return true;

}



#ifdef CONFIG_MEMORY_ISOLATION

static inline unsigned long nr_zone_isolate_freepages(struct zone *zone)

{

	if (unlikely(zone->nr_pageblock_isolate))

		return zone->nr_pageblock_isolate * pageblock_nr_pages;

	return 0;

}

#else

static inline unsigned long nr_zone_isolate_freepages(struct zone *zone)

{

	return 0;

}

#endif



bool zone_watermark_ok(struct zone *z, int order, unsigned long mark,

		      int classzone_idx, int alloc_flags)

{
@@ -1684,14 +1665,6 @@ bool zone_watermark_ok_safe(struct zone *z, int order, unsigned long mark, 
	if (z->percpu_drift_mark && free_pages < z->percpu_drift_mark)

		free_pages = zone_page_state_snapshot(z, NR_FREE_PAGES);



	/*

	 * If the zone has MIGRATE_ISOLATE type free pages, we should consider

	 * it.  nr_zone_isolate_freepages is never accurate so kswapd might not

	 * sleep although it could do so.  But this is more desirable for memory

	 * hotplug than sleeping which can cause a livelock in the direct

	 * reclaim path.

	 */

	free_pages -= nr_zone_isolate_freepages(z);

	return __zone_watermark_ok(z, order, mark, classzone_idx, alloc_flags,

								free_pages);

}

mm/page_isolation.c

+2 −24
Original line number Diff line number Diff line
@@ -8,28 +8,6 @@ 
#include <linux/memory.h>

#include "internal.h"



/* called while holding zone->lock */

static void set_pageblock_isolate(struct page *page)

{

	if (get_pageblock_migratetype(page) == MIGRATE_ISOLATE)

		return;



	set_pageblock_migratetype(page, MIGRATE_ISOLATE);

	page_zone(page)->nr_pageblock_isolate++;

}



/* called while holding zone->lock */

static void restore_pageblock_isolate(struct page *page, int migratetype)

{

	struct zone *zone = page_zone(page);

	if (WARN_ON(get_pageblock_migratetype(page) != MIGRATE_ISOLATE))

		return;



	BUG_ON(zone->nr_pageblock_isolate <= 0);

	set_pageblock_migratetype(page, migratetype);

	zone->nr_pageblock_isolate--;

}



int set_migratetype_isolate(struct page *page, bool skip_hwpoisoned_pages)

{

	struct zone *zone;
@@ -80,7 +58,7 @@ out: 
		unsigned long nr_pages;

		int migratetype = get_pageblock_migratetype(page);



		set_pageblock_isolate(page);

		set_pageblock_migratetype(page, MIGRATE_ISOLATE);

		nr_pages = move_freepages_block(zone, page, MIGRATE_ISOLATE);



		__mod_zone_freepage_state(zone, -nr_pages, migratetype);
@@ -103,7 +81,7 @@ void unset_migratetype_isolate(struct page *page, unsigned migratetype) 
		goto out;

	nr_pages = move_freepages_block(zone, page, migratetype);

	__mod_zone_freepage_state(zone, nr_pages, migratetype);

	restore_pageblock_isolate(page, migratetype);

	set_pageblock_migratetype(page, migratetype);

out:

	spin_unlock_irqrestore(&zone->lock, flags);

}

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